Faraday As A Discoverer...................................................................................................................................1

Daily and weekly, from all parts of the world, I receive publications bearing upon the practical applications of

electricity. This great movement, the ultimate outcome of which is not to be foreseen, had its origin in the

discoveries made by Michael Faraday, sixtytwo years ago. From these discoveries have sprung applications

of the telephone order, together with various forms of the electric telegraph. From them have sprung the

extraordinary advances made in electrical illumination. Faraday could have had but an imperfect notion of the

expansions of which his discoveries were capable. Still he had a vivid and strong imagination, and I do not

doubt that he saw possibilities which did not disclose themselves to the general scientific mind. He knew that

his discoveries had their practical side, but he steadfastly resisted the seductions of this side, applying himself

to the development of principles; being well aware that the practical question would receive due development

During my sojourn in Switzerland this year, I read through the proofs of this new edition, and by my reading

was confirmed in the conviction that the book ought not to be suffered to go out of print. The memoir was

written under great pressure, but I am not ashamed of it as it stands. Glimpses of Faraday's character and

gleams of his discoveries are there to be found which will be of interest to humanity to the end of time.

When consulted a short time ago as to the republication of 'Faraday as a Discoverer,' it seemed to me that the

labours, and points of character, of so great a worker and so good a man should not be allowed to vanish from

the public eye. I therefore willingly fell in with the proposal of my Publishers to issue a new edition of the

The experimental researches of Faraday are so voluminous, their descriptions are so detailed, and their wealth

of illustration is so great, as to render it a heavy labour to master them. The multiplication of proofs,

necessary and interesting when the new truths had to be established, are however less needful now when

these truths have become household words in science. I have therefore tried in the following pages to

compress the body, without injury to the spirit, of these imperishable investigations, and to present them in a

While I write, the volumes of the Life of Faraday by Dr. Bence Jones have reached my hands. To them the

reader must refer for an account of Faraday's private relations. A hasty glance at the work shows me that the

reverent devotion of the biographer has turned to admirable account the materials at his command.

The work of Dr. Bence Jones enables me to correct a statement regarding Wollaston's and Faraday's

respective relations to the discovery of Magnetic Rotation. Wollaston's idea was to make the wire carrying a

current rotate round its own axis: an idea afterwards realised by the celebrated Ampere. Faraday's discovery

was to make the wire carrying the current revolve round the pole of a magnet and the reverse.

Parentage: introduction to the royal institution: earliest experiments: first royal society paper: marriage.

It has been thought desirable to give you and the world some image of MICHAEL FARADAY, as a scientific

investigator and discoverer. The attempt to respond to this desire has been to me a labour of difficulty, if also

a labour of love. For however well acquainted I may be with the researches and discoveries of that great

masterhowever numerous the illustrations which occur to me of the loftiness of Faraday's character and the

beauty of his lifestill to grasp him and his researches as a whole; to seize upon the ideas which guided him,

and connected them; to gain entrance into that strong and active brain, and read from it the riddle of the

world this is a work not easy of performance, and all but impossible amid the distraction of duties of

another kind. That I should at one period or another speak to you regarding Faraday and his work is natural, if

not inevitable; but I did not expect to be called upon to speak so soon. Still the bare suggestion that this is the

fit and proper time for speech sent me immediately to my task: from it I have returned with such results as I

could gather, and also with the wish that those results were more worthy than they are of the greatness of my

It is not my intention to lay before you a life of Faraday in the ordinary acceptation of the term. The duty I

have to perform is to give you some notion of what he has done in the world; dwelling incidentally on the

spirit in which his work was executed, and introducing such personal traits as may be necessary to the

completion of your picture of the philosopher, though by no means adequate to give you a complete idea of

The newspapers have already informed you that Michael Faraday was born at Newington Butts, on

September 22, 1791, and that he died at Hampton Court, on August 25, 1867. Believing, as I do, in the

general truth of the doctrine of hereditary transmissionsharing the opinion of Mr. Carlyle, that 'a really

able man never proceeded from entirely stupid parents'I once used the privilege of my intimacy with Mr.

Faraday to ask him whether his parents showed any signs of unusual ability. He could remember none. His

father, I believe, was a great sufferer during the latter years of his life, and this might have masked whatever

intellectual power he possessed. When thirteen years old, that is to say in 1804, Faraday was apprenticed to a

bookseller and bookbinder in Blandford Street, Manchester Square: here he spent eight years of his life, after

You have also heard the account of Faraday's first contact with the Royal Institution; that he was introduced

by one of the members to Sir Humphry Davy's last lectures, that he took notes of those lectures; wrote them

fairly out, and sent them to Davy, entreating him at the same time to enable him to quit trade, which he

detested, and to pursue science, which he loved. Davy was helpful to the young man, and this should never be

forgotten: he at once wrote to Faraday, and afterwards, when an opportunity occurred, made him his

assistant.[1] Mr. Gassiot has lately favoured me with the following reminiscence of this time:

'My Dear Tyndall,Sir H. Davy was accustomed to call on the late Mr. Pepys, in the Poultry, on his way to

the London Institution, of which Pepys was one of the original managers; the latter told me that on one

occasion Sir H. Davy, showing him a letter, said: "Pepys, what am I to do, here is a letter from a young man

named Faraday; he has been attending my lectures, and wants me to give him employment at the Royal

Institutionwhat can I do?" "Do?" replied Pepys, "put him to wash bottles; if he is good for anything he will

do it directly, if he refuses he is good for nothing." "No, no," replied Davy; "we must try him with something

better than that." The result was, that Davy engaged him to assist in the Laboratory at weekly wages.

'Davy held the joint office of Professor of Chemistry and Director of the Laboratory; he ultimately gave up

the former to the late Professor Brande, but he insisted that Faraday should be appointed Director of the

Laboratory, and, as Faraday told me, this enabled him on subsequent occasions to hold a definite position in

the Institution, in which he was always supported by Davy. I believe he held that office to the last.

From a letter written by Faraday himself soon after his appointment as Davy's assistant, I extract the

following account of his introduction to the Royal Institution: 'London, Sept. 13, 1813.

'As for myself, I am absent (from home) nearly day and night, except occasional calls, and it is likely shall

shortly be absent entirely, but this (having nothing more to say, and at the request of my mother) I will

explain to you. I was formerly a bookseller and binder, but am now turned philosopher,[2] which happened

thus: Whilst an apprentice, I, for amusement, learnt a little chemistry and other parts of philosophy, and

felt an eager desire to proceed in that way further. After being a journeyman for six months, under a

disagreeable master, I gave up my business, and through the interest of a Sir H. Davy, filled the situation of

chemical assistant to the Royal Institution of Great Britain, in which office I now remain; and where I am

constantly employed in observing the works of nature, and tracing the manner in which she directs the order

and arrangement of the world. I have lately had proposals made to me by Sir Humphry Davy to accompany

him in his travels through Europe and Asia, as philosophical assistant. If I go at all I expect it will be in

October nextabout the end; and my absence from home will perhaps be as long as three years. But as yet

This account is supplemented by the following letter, written by Faraday to his friend De la Rive,[3] on the

'My Dear Friend,Your subject interested me deeply every way; for Mrs. Marcet was a good friend to me,

as she must have been to many of the human race. I entered the shop of a bookseller and bookbinder at the

age of thirteen, in the year 1804, remained there eight years, and during the chief part of my time bound

books. Now it was in those books, in the hours after work, that I found the beginning of my philosophy.

There were two that especially helped me, the "Encyclopaedia Britannica," from which I gained my first

notions of electricity, and Mrs. Marcet's "Conversation on Chemistry," which gave me my foundation in that

'Do not suppose that I was a very deep thinker, or was marked as a precocious person. I was a very lively

imaginative person, and could believe in the "Arabian Nights" as easily as in the "Encyclopaedia." But facts

were important to me, and saved me. I could trust a fact, and always crossexamined an assertion. So when I

questioned Mrs. Marcet's book by such little experiments as I could find means to perform, and found it true

to the facts as I could understand them, I felt that I had got hold of an anchor in chemical knowledge, and

clung fast to it. Thence my deep veneration for Mrs. Marcetfirst as one who had conferred great personal

good and pleasure on me; and then as one able to convey the truth and principle of those boundless fields of

knowledge which concern natural things to the young, untaught, and inquiring mind.

'You may imagine my delight when I came to know Mrs. Marcet personally; how often I cast my thoughts

backward, delighting to connect the past and the present; how often, when sending a paper to her as a

thankoffering, I thought of my first instructress, and such like thoughts will remain with me.

'I have some such thoughts even as regards your own father; who was, I may say, the first who personally at

Geneva, and afterwards by correspondence, encouraged, and by that sustained me.'

Twelve or thirteen years ago Mr. Faraday and myself quitted the Institution one evening together, to pay a

visit to our friend Grove in Baker Street. He took my arm at the door, and, pressing it to his side in his warm

genial way, said, 'Come, Tyndall, I will now show you something that will interest you.' We walked

northwards, passed the house of Mr. Babbage, which drew forth a reference to the famous evening parties

once assembled there. We reached Blandford Street, and after a little looking about he paused before a

stationer's shop, and then went in. On entering the shop, his usual animation seemed doubled; he looked

rapidly at everything it contained. To the left on entering was a door, through which he looked down into a

little room, with a window in front facing Blandford Street. Drawing me towards him, he said eagerly, 'Look

there, Tyndall, that was my workingplace. I bound books in that little nook.' A respectablelooking woman

stood behind the counter: his conversation with me was too low to be heard by her, and he now turned to the

counter to buy some cards as an excuse for our being there. He asked the woman her nameher

predecessor's name his predecessor's name. 'That won't do,' he said, with goodhumoured impatience;

'who was his predecessor?' 'Mr. Riebau,' she replied, and immediately added, as if suddenly recollecting

herself, 'He, sir, was the master of Sir Charles Faraday.' 'Nonsense!' he responded, 'there is no such person.'

Great was her delight when I told her the name of her visitor; but she assured me that as soon as she saw him

running about the shop, she feltthough she did not know whythat it must be 'Sir Charles Faraday.'

Faraday did, as you know, accompany Davy to Rome: he was reengaged by the managers of the Royal

Institution on May 15, 1815. Here he made rapid progress in chemistry, and after a time was entrusted with

easy analyses by Davy. In those days the Royal Institution published 'The Quarterly Journal of Science,' the

precursor of our own 'Proceedings.' Faraday's first contribution to science appeared in that journal in 1816. It

was an analysis of some caustic lime from Tuscany, which had been sent to Davy by the Duchess of

Montrose. Between this period and 1818 various notes and short papers were published by Faraday. In 1818

he experimented upon 'Sounding Flames.' Professor Auguste De la Rive had investigated those sounding

flames, and had applied to them an explanation which completely accounted for a class of sounds discovered

by himself, but did not account for those known to his predecessors. By a few simple and conclusive

experiments, Faraday proved the explanation insufficient. It is an epoch in the life of a young man when he

finds himself correcting a person of eminence, and in Faraday's case, where its effect was to develop a

From time to time between 1818 and 1820 Faraday published scientific notes and notices of minor weight. At

this time he was acquiring, not producing; working hard for his master and storing and strengthening his own

mind. He assisted Mr. Brande in his lectures, and so quietly, skilfully, and modestly was his work done, that

Mr. Brande's vocation at the time was pronounced 'lecturing on velvet.' In 1820 Faraday published a chemical

paper 'on two new compounds of chlorine and carbon, and on a new compound of iodine, carbon, and

hydrogen.' This paper was read before the Royal Society on December 21, 1820, and it was the first of his

On June 12, 1821, he married, and obtained leave to bring his young wife into his rooms at the Royal

Institution. There for fortysix years they lived together, occupying the suite of apartments which had been

previously in the successive occupancy of Young, Davy, and Brande. At the time of her marriage Mrs.

Faraday was twentyone years of age, he being nearly thirty. Regarding this marriage I will at present limit

myself to quoting an entry written in Faraday's own hand in his book of diplomas, which caught my eye

'25th January, 1847. 'Amongst these records and events, I here insert the date of one which, as a source of

honour and happiness, far exceeds all the rest. We were married on June 12, 1821.

Then follows the copy of the minutes, dated May 21, 1821, which gave him additional rooms, and thus

enabled him to bring his wife to the Royal Institution. A feature of Faraday's character which I have often

noticed makes itself apparent in this entry. In his relations to his wife he added chivalry to affection.

[1] Here is Davy's recommendation of Faraday, presented to the managers of the Royal Institution, at a

'Sir Humphry Davy has the honour to inform the managers that he has found a person who is desirous to

occupy the situation in the Institution lately filled by William Payne. His name is Michael Faraday. He is a

youth of twentytwo years of age. As far as Sir H. Davy has been able to observe or ascertain, he appears

well fitted for the situation. His habits seem good; his disposition active and cheerful, and his manner

intelligent. He is willing to engage himself on the same terms as given to Mr. Payne at the time of quitting the

'Resolved,That Michael Faraday be engaged to fill the situation lately occupied by Mr. Payne, on the same

[2] Faraday loved this word and employed it to the last; he had an intense dislike to the modern term

Early researches: magnetic rotations: liquefaction of gases: heavy glass: Charles Anderson: contributions to

Oersted, in 1820, discovered the action of a voltaic current on a magnetic needle; and immediately afterwards

the splendid intellect of Ampere succeeded in showing that every magnetic phenomenon then known might

be reduced to the mutual action of electric currents. The subject occupied all men's thoughts: and in this

country Dr. Wollaston sought to convert the deflection of the needle by the current into a permanent rotation

of the needle round the current. He also hoped to produce the reciprocal effect of causing a current to rotate

round a magnet. In the early part of 1821, Wollaston attempted to realise this idea in the presence of Sir

Humphry Davy in the laboratory of the Royal Institution.[1] This was well calculated to attract Faraday's

attention to the subject. He read much about it; and in the months of July, August, and September he wrote a

'history of the progress of electromagnetism,' which he published in Thomson's 'Annals of Philosophy.'

Soon afterwards he took up the subject of 'Magnetic Rotations,' and on the morning of Christmasday, 1821,

he called his wife to witness, for the first time, the revolution of a magnetic needle round an electric current.

Incidental to the 'historic sketch,' he repeated almost all the experiments there referred to; and these, added to

his own subsequent work, made him practical master of all that was then known regarding the voltaic current.

In 1821, he also touched upon a subject which subsequently received his closer attentionthe vaporization

of mercury at common temperatures; and immediately afterwards conducted, in company with Mr. Stodart,

experiments on the alloys of steel. He was accustomed in after years to present to his friends razors formed

During Faraday's hours of liberty from other duties, he took up subjects of inquiry for himself; and in the

spring of 1823, thus selfprompted, he began the examination of a substance which had long been regarded

as the chemical element chlorine, in a solid form, but which Sir Humphry Davy, in 1810, had proved to be a

hydrate of chlorine, that is, a compound of chlorine and water. Faraday first analysed this hydrate, and wrote

out an account of its composition. This account was looked over by Davy, who suggested the heating of the

hydrate under pressure in a sealed glass tube. This was done. The hydrate fused at a bloodheat, the tube

became filled with a yellow atmosphere, and was afterwards found to contain two liquid substances. Dr. Paris

happened to enter the laboratory while Faraday was at work. Seeing the oily liquid in his tube, he rallied the

young chemist for his carelessness in employing soiled vessels. On filing off the end of the tube, its contents

exploded and the oily matter vanished. Early next morning, Dr. Paris received the following note:

The gas had been liquefied by its own pressure. Faraday then tried compression with a syringe, and

To the published account of this experiment Davy added the following note:'In desiring Mr. Faraday to

expose the hydrate of chlorine in a closed glass tube, it occurred to me that one of three things would happen:

that decomposition of water would occur;... or that the chlorine would separate in a fluid state.' Davy,

moreover, immediately applied the method of selfcompressing atmosphere to the liquefaction of muriatic

gas. Faraday continued the experiments, and succeeded in reducing a number of gases till then deemed

permanent to the liquid condition. In 1844 he returned to the subject, and considerably expanded its limits.

These important investigations established the fact that gases are but the vapours of liquids possessing a very

low boilingpoint, and gave a sure basis to our views of molecular aggregation. The account of the first

investigation was read before the Royal Society on April 10, 1823, and was published, in Faraday's name, in

the 'Philosophical Transactions.' The second memoir was sent to the Royal Society on December 19, 1844. I

may add that while he was conducting his first experiments on the liquefaction of gases, thirteen pieces of

Some small notices and papers, including the observation that glass readily changes colour in sunlight, follow

here. In 1825 and 1826 Faraday published papers in the 'Philosophical Transactions' on 'new compounds of

carbon and hydrogen,' and on 'sulphonaphthalic acid.' In the former of these papers he announced the

discovery of Benzol, which, in the hands of modern chemists, has become the foundation of our splendid

aniline dyes. But he swerved incessantly from chemistry into physics; and in 1826 we find him engaged in

investigating the limits of vaporization, and showing, by exceedingly strong and apparently conclusive

arguments, that even in the case of mercury such a limit exists; much more he conceived it to be certain that

our atmosphere does not contain the vapour of the fixed constituents of the earth's crust. This question, I may

say, is likely to remain an open one. Dr. Rankine, for example, has lately drawn attention to the odour of

certain metals; whence comes this odour, if it be not from the vapour of the metal?

In 1825 Faraday became a member of a committee, to which Sir John Herschel and Mr. Dollond also

belonged, appointed by the Royal Society to examine, and if possible improve, the manufacture of glass for

optical purposes. Their experiments continued till 1829, when the account of them constituted the subject of a

'Bakerian Lecture.' This lectureship, founded in 1774 by Henry Baker, Esq., of the Strand, London, provides

that every year a lecture shall be given before the Royal Society, the sum of four pounds being paid to the

lecturer. The Bakerian Lecture, however, has long since passed from the region of pay to that of honour,

papers of mark only being chosen for it by the council of the Society. Faraday's first Bakerian Lecture, 'On

the Manufacture of Glass for Optical Purposes,' was delivered at the close of 1829. It is a most elaborate and

conscientious description of processes, precautions, and results: the details were so exact and so minute, and

the paper consequently so long, that three successive sittings of the Royal Society were taken up by the

delivery of the lecture.[3] This glass did not turn out to be of important practical use, but it happened

The experiments here referred to were commenced at the Falcon Glass Works, on the premises of Messrs.

Green and Pellatt, but Faraday could not conveniently attend to them there. In 1827, therefore, a furnace was

erected in the yard of the Royal Institution; and it was at this time, and with a view of assisting him at the

furnace, that Faraday engaged Sergeant Anderson, of the Royal Artillery, the respectable, truthful, and

altogether trustworthy man whose appearance here is so fresh in our memories. Anderson continued to be the

reverential helper of Faraday and the faithful servant of this Institution for nearly forty years.[5]

In 1831 Faraday published a paper, 'On a peculiar class of Optical Deceptions,' to which I believe the

beautiful optical toy called the Chromatrope owes its origin. In the same year he published a paper on

Vibrating Surfaces, in which he solved an acoustical problem which, though of extreme simplicity when

solved, appears to have baffled many eminent men. The problem was to account for the fact that light bodies,

such as the seed of lycopodium, collected at the vibrating parts of sounding plates, while sand ran to the nodal

lines. Faraday showed that the light bodies were entangled in the little whirlwinds formed in the air over the

places of vibration, and through which the heavier sand was readily projected. Faraday's resources as an

experimentalist were so wonderful, and his delight in experiment was so great, that he sometimes almost ran

into excess in this direction. I have heard him say that this paper on vibrating surfaces was too heavily laden

[1] The reader's attention is directed to the concluding paragraph of the 'Preface to the Second Edition written

in December, 1869. Also to the Life of Faraday by Dr. Bence Jones, vol. i. p. 338 et seq.

[4] I make the following extract from a letter from Sir John Herschel, written to me from Collingwood, on the

'I will take this opportunity to mention that I believe myself to have originated the suggestion of the

employment of borate of lead for optical purposes. It was somewhere in the year 1822, as well as I can

recollect, that I mentioned it to Sir James (then Mr.) South; and, in consequence, the trial was made in his

laboratory in Blackman Street, by precipitating and working a large quantity of borate of lead, and fusing it

under a muffle in a porcelain evaporating dish. A very limpid (though slightly yellow) glass resulted, the

refractive index 1.866! (which you will find set down in my table of refractive indices in my article "Light,"

Encyclopaedia Metropolitana). It was, however, too soft for optical use as an objectglass. This Faraday

[5] Regarding Anderson, Faraday writes thus in 1845:'I cannot resist the occasion that is thus offered to me

of mentioning the name of Mr. Anderson, who came to me as an assistant in the glass experiments, and has

remained ever since in the laboratory of the Royal Institution. He assisted me in all the researches into which

I have entered since that time; and to his care, steadiness, exactitude, and faithfulness in the performance of

all that has been committed to his charge, I am much indebted.M. F.' (Exp. Researches, vol. iii. p. 3,

Discovery of Magnetoelectricity: Explanation of Argo's magnetism of rotation: Terrestrial magnetoelectric

The work thus referred to, though sufficient of itself to secure no mean scientific reputation, forms but the

vestibule of Faraday's achievements. He had been engaged within these walls for eighteen years. During part

of the time he had drunk in knowledge from Davy, and during the remainder he continually exercised his

capacity for independent inquiry. In 1831 we have him at the climax of his intellectual strength, forty years of

age, stored with knowledge and full of original power. Through reading, lecturing, and experimenting, he had

become thoroughly familiar with electrical science: he saw where light was needed and expansion possible.

The phenomena of ordinary electric induction belonged, as it were, to the alphabet of his knowledge: he knew

that under ordinary circumstances the presence of an electrified body was sufficient to excite, by induction,

an unelectrified body. He knew that the wire which carried an electric current was an electrified body, and

still that all attempts had failed to make it excite in other wires a state similar to its own.

What was the reason of this failure? Faraday never could work from the experiments of others, however

clearly described. He knew well that from every experiment issues a kind of radiation, luminous in different

degrees to different minds, and he hardly trusted himself to reason upon an experiment that he had not seen.

In the autumn of 1831 he began to repeat the experiments with electric currents, which, up to that time, had

produced no positive result. And here, for the sake of younger inquirers, if not for the sake of us all, it is

worth while to dwell for a moment on a power which Faraday possessed in an extraordinary degree. He

united vast strength with perfect flexibility. His momentum was that of a river, which combines weight and

directness with the ability to yield to the flexures of its bed. The intentness of his vision in any direction did

not apparently diminish his power of perception in other directions; and when he attacked a subject,

expecting results he had the faculty of keeping his mind alert, so that results different from those which he

He began his experiments 'on the induction of electric currents' by composing a helix of two insulated wires

which were wound side by side round the same wooden cylinder. One of these wires he connected with a

voltaic battery of ten cells, and the other with a sensitive galvanometer. When connection with the battery

was made, and while the current flowed, no effect whatever was observed at the galvanometer. But he never

accepted an experimental result, until he had applied to it the utmost power at his command. He raised his

battery from 10 cells to 120 cells, but without avail. The current flowed calmly through the battery wire

'During its flow,' and this was the time when an effect was expected but here Faraday's power of lateral

vision, separating, as it were, from the line of expectation, came into playhe noticed that a feeble

movement of the needle always occurred at the moment when he made contact with the battery; that the

needle would afterwards return to its former position and remain quietly there unaffected by the flowing

current. At the moment, however, when the circuit was interrupted the needle again moved, and in a direction

This result, and others of a similar kind, led him to the conclusion 'that the battery current through the one

wire did in reality induce a similar current through the other; but that it continued for an instant only, and

partook more of the nature of the electric wave from a common Leyden jar than of the current from a voltaic

battery.' The momentary currents thus generated were called induced currents, while the current which

generated them was called the inducing current. It was immediately proved that the current generated at

making the circuit was always opposed in direction to its generator, while that developed on the rupture of the

circuit coincided in direction with the inducing current. It appeared as if the current on its first rush through

the primary wire sought a purchase in the secondary one, and, by a kind of kick, impelled backward through

the latter an electric wave, which subsided as soon as the primary current was fully established.

Faraday, for a time, believed that the secondary wire, though quiescent when the primary current had been

once established, was not in its natural condition, its return to that condition being declared by the current

observed at breaking the circuit. He called this hypothetical state of the wire the electrotonic state: he

afterwards abandoned this hypothesis, but seemed to return to it in later life. The term electrotonic is also

preserved by Professor Du Bois Reymond to express a certain electric condition of the nerves, and Professor

Clerk Maxwell has ably defined and illustrated the hypothesis in the Tenth Volume of the 'Transactions of the

The mere approach of a wire forming a closed curve to a second wire through which a voltaic current flowed

was then shown by Faraday to be sufficient to arouse in the neutral wire an induced current, opposed in

direction to the inducing current; the withdrawal of the wire also generated a current having the same

direction as the inducing current; those currents existed only during the time of approach or withdrawal, and

when neither the primary nor the secondary wire was in motion, no matter how close their proximity might

Faraday has been called a purely inductive philosopher. A great deal of nonsense is, I fear, uttered in this land

of England about induction and deduction. Some profess to befriend the one, some the other, while the real

vocation of an investigator, like Faraday, consists in the incessant marriage of both. He was at this time full

of the theory of Ampere, and it cannot be doubted that numbers of his experiments were executed merely to

test his deductions from that theory. Starting from the discovery of Oersted, the illustrious French

philosopher had shown that all the phenomena of magnetism then known might be reduced to the mutual

attractions and repulsions of electric currents. Magnetism had been produced from electricity, and Faraday,

who all his life long entertained a strong belief in such reciprocal actions, now attempted to effect the

evolution of electricity from magnetism. Round a welded iron ring he placed two distinct coils of covered

wire, causing the coils to occupy opposite halves of the ring. Connecting the ends of one of the coils with a

galvanometer, he found that the moment the ring was magnetised, by sending a current through the other coil,

the galvanometer needle whirled round four or five times in succession. The action, as before, was that of a

pulse, which vanished immediately. On interrupting the circuit, a whirl of the needle in the opposite direction

occurred. It was only during the time of magnetization or demagnetization that these effects were produced.

The induced currents declared a change of condition only, and they vanished the moment the act of

The effects obtained with the welded ring were also obtained with straight bars of iron. Whether the bars

were magnetised by the electric current, or were excited by the contact of permanent steel magnets, induced

currents were always generated during the rise, and during the subsidence of the magnetism. The use of iron

was then abandoned, and the same effects were obtained by merely thrusting a permanent steel magnet into a

coil of wire. A rush of electricity through the coil accompanied the insertion of the magnet; an equal rush in

the opposite direction accompanied its withdrawal. The precision with which Faraday describes these results,

and the completeness with which he defines the boundaries of his facts, are wonderful. The magnet, for

example, must not be passed quite through the coil, but only half through; for if passed wholly through, the

needle is stopped as by a blow, and then he shows how this blow results from a reversal of the electric wave

in the helix. He next operated with the powerful permanent magnet of the Royal Society, and obtained with it,

And now he turned the light of these discoveries upon the darkest physical phenomenon of that day. Arago

had discovered, in 1824, that a disk of nonmagnetic metal had the power of bringing a vibrating magnetic

needle suspended over it rapidly to rest; and that on causing the disk to rotate the magnetic needle rotated

along with it. When both were quiescent, there was not the slightest measurable attraction or repulsion

exerted between the needle and the disk; still when in motion the disk was competent to drag after it, not only

a light needle, but a heavy magnet. The question had been probed and investigated with admirable skill both

by Arago and Ampere, and Poisson had published a theoretic memoir on the subject; but no cause could be

assigned for so extraordinary an action. It had also been examined in this country by two celebrated men, Mr.

Babbage and Sir John Herschel; but it still remained a mystery. Faraday always recommended the suspension

of judgment in cases of doubt. 'I have always admired,' he says, 'the prudence and philosophical reserve

shown by M. Arago in resisting the temptation to give a theory of the effect he had discovered, so long as he

could not devise one which was perfect in its application, and in refusing to assent to the imperfect theories of

others.' Now, however, the time for theory had come. Faraday saw mentally the rotating disk, under the

operation of the magnet, flooded with his induced currents, and from the known laws of interaction between

currents and magnets he hoped to deduce the motion observed by Arago. That hope he realised, showing by

actual experiment that when his disk rotated currents passed through it, their position and direction being

such as must, in accordance with the established laws of electromagnetic action, produce the observed

Introducing the edge of his disk between the poles of the large horseshoe magnet of the Royal Society, and

connecting the axis and the edge of the disk, each by a wire with a galvanometer, he obtained, when the disk

was turned round, a constant flow of electricity. The direction of the current was determined by the direction

of the motion, the current being reversed when the rotation was reversed. He now states the law which rules

the production of currents in both disks and wires, and in so doing uses, for the first time, a phrase which has

since become famous. When iron filings are scattered over a magnet, the particles of iron arrange themselves

in certain determinate lines called magnetic curves. In 1831, Faraday for the first time called these curves

'lines of magnetic force'; and he showed that to produce induced currents neither approach to nor withdrawal

from a magnetic source, or centre, or pole, was essential, but that it was only necessary to cut appropriately

the lines of magnetic force. Faraday's first paper on Magnetoelectric Induction, which I have here

endeavoured to condense, was read before the Royal Society on the 24th of November, 1831.

On January 12, 1832, he communicated to the Royal Society a second paper on Terrestrial Magnetoelectric

Induction, which was chosen as the Bakerian Lecture for the year. He placed a bar of iron in a coil of wire,

and lifting the bar into the direction of the dipping needle, he excited by this action a current in the coil. On

reversing the bar, a current in the opposite direction rushed through the wire. The same effect was produced

when, on holding the helix in the line of dip, a bar of iron was thrust into it. Here, however, the earth acted on

the coil through the intermediation of the bar of iron. He abandoned the bar and simply set a copper plate

spinning in a horizontal plane; he knew that the earth's lines of magnetic force then crossed the plate at an

angle of about 70degrees. When the plate spun round, the lines of force were intersected and induced currents

generated, which produced their proper effect when carried from the plate to the galvanometer. 'When the

plate was in the magnetic meridian, or in any other plane coinciding with the magnetic dip, then its rotation

At the suggestion of a mind fruitful in suggestions of a profound and philosophic characterI mean that of

Sir John Herschel Mr. Barlow, of Woolwich, had experimented with a rotating iron shell. Mr. Christie had

also performed an elaborate series of experiments on a rotating iron disk. Both of them had found that when

in rotation the body exercised a peculiar action upon the magnetic needle, deflecting it in a manner which was

not observed during quiescence; but neither of them was aware at the time of the agent which produced this

extraordinary deflection. They ascribed it to some change in the magnetism of the iron shell and disk.

But Faraday at once saw that his induced currents must come into play here, and he immediately obtained

them from an iron disk. With a hollow brass ball, moreover, he produced the effects obtained by Mr. Barlow.

Iron was in no way necessary: the only condition of success was that the rotating body should be of a

character to admit of the formation of currents in its substance: it must, in other words, be a conductor of

electricity. The higher the conducting power the more copious were the currents. He now passes from his

little brass globe to the globe of the earth. He plays like a magician with the earth's magnetism. He sees the

invisible lines along which its magnetic action is exerted, and sweeping his wand across these lines evokes

this new power. Placing a simple loop of wire round a magnetic needle he bends its upper portion to the west:

the north pole of the needle immediately swerves to the east: he bends his loop to the east, and the north pole

moves to the west. Suspending a common bar magnet in a vertical position, he causes it to spin round its own

axis. Its pole being connected with one end of a galvanometer wire, and its equator with the other end,

electricity rushes round the galvanometer from the rotating magnet. He remarks upon the 'singular

independence' of the magnetism and the body of the magnet which carries it. The steel behaves as if it were

And then his thoughts suddenly widen, and he asks himself whether the rotating earth does not generate

induced currents as it turns round its axis from west to east. In his experiment with the twirling magnet the

galvanometer wire remained at rest; one portion of the circuit was in motion relatively to another portion. But

in the case of the twirling planet the galvanometer wire would necessarily be carried along with the earth;

there would be no relative motion. What must be the consequence? Take the case of a telegraph wire with its

two terminal plates dipped into the earth, and suppose the wire to lie in the magnetic meridian. The ground

underneath the wire is influenced like the wire itself by the earth's rotation; if a current from south to north be

generated in the wire, a similar current from south to north would be generated in the earth under the wire;

these currents would run against the same terminal plate, and thus neutralise each other.

This inference appears inevitable, but his profound vision perceived its possible invalidity. He saw that it was

at least possible that the difference of conducting power between the earth and the wire might give one an

advantage over the other, and that thus a residual or differential current might be obtained. He combined

wires of different materials, and caused them to act in opposition to each other, but found the combination

ineffectual. The more copious flow in the better conductor was exactly counterbalanced by the resistance of

the worse. Still, though experiment was thus emphatic, he would clear his mind of all discomfort by operating

on the earth itself. He went to the round lake near Kensington Palace, and stretched 480 feet of copper wire,

north and south, over the lake, causing plates soldered to the wire at its ends to dip into the water. The copper

wire was severed at the middle, and the severed ends connected with a galvanometer. No effect whatever was

observed. But though quiescent water gave no effect, moving water might. He therefore worked at London

Bridge for three days during the ebb and flow of the tide, but without any satisfactory result. Still he urges,

'Theoretically it seems a necessary consequence, that where water is flowing there electric currents should be

formed. If a line be imagined passing from Dover to Calais through the sea, and returning through the land,

beneath the water, to Dover, it traces out a circuit of conducting matter one part of which, when the water

moves up or down the channel, is cutting the magnetic curves of the earth, whilst the other is relatively at

rest.... There is every reason to believe that currents do run in the general direction of the circuit described,

either one way or the other, according as the passage of the waters is up or down the channel.' This was

written before the submarine cable was thought of, and he once informed me that actual observation upon

Three years subsequent to the publication of these researches that is to say, on January 29, 1835Faraday

read before the Royal Society a paper 'On the influence by induction of an electric current upon itself.' A

shock and spark of a peculiar character had been observed by a young man named William Jenkin, who must

have been a youth of some scientific promise, but who, as Faraday once informed me, was dissuaded by his

own father from having anything to do with science. The investigation of the fact noticed by Mr. Jenkin led

Faraday to the discovery of the extra current, or the current induced in the primary wire itself at the moments

of making and breaking contact, the phenomena of which he described and illustrated in the beautiful and

Sevenandthirty years have passed since the discovery of magnetoelectricity; but, if we except the extra

current, until quite recently nothing of moment was added to the subject. Faraday entertained the opinion that

the discoverer of a great law or principle had a right to the 'spoils'this was his termarising from its

illustration; and guided by the principle he had discovered, his wonderful mind, aided by his wonderful ten

fingers, overran in a single autumn this vast domain, and hardly left behind him the shred of a fact to be

And here the question may arise in some minds, What is the use of it all? The answer is, that if man's

intellectual nature thirsts for knowledge, then knowledge is useful because it satisfies this thirst. If you

demand practical ends, you must, I think, expand your definition of the term practical, and make it include all

that elevates and enlightens the intellect, as well as all that ministers to the bodily health and comfort of men.

Still, if needed, an answer of another kind might be given to the question 'What is its use?' As far as

electricity has been applied for medical purposes, it has been almost exclusively Faraday's electricity. You

have noticed those lines of wire which cross the streets of London. It is Faraday's currents that speed from

place to place through these wires. Approaching the point of Dungeness, the mariner sees an unusually

brilliant light, and from the noble phares of La Heve the same light flashes across the sea. These are Faraday's

sparks exalted by suitable machinery to sunlike splendour. At the present moment the Board of Trade and the

Brethren of the Trinity House, as well as the Commissioners of Northern Lights, are contemplating the

introduction of the Magnetoelectric Light at numerous points upon our coasts; and future generations will

be able to refer to those guiding stars in answer to the question. What has been the practical use of the labours

of Faraday? But I would again emphatically say, that his work needs no such justification, and that if he had

allowed his vision to be disturbed by considerations regarding the practical use of his discoveries, those

discoveries would never have been made by him. 'I have rather,' he writes in 1831, 'been desirous of

discovering new facts and new relations dependent on magnetoelectric induction, than of exalting the force

of those already obtained; being assured that the latter would find their full development hereafter.'

In 1817, when lecturing before a private society in London on the element chlorine, Faraday thus expressed

himself with reference to this question of utility. 'Before leaving this subject, I will point out the history of

this substance, as an answer to those who are in the habit of saying to every new fact. "What is its use?" Dr.

Franklin says to such, "What is the use of an infant?" The answer of the experimentalist is, "Endeavour to

make it useful." When Scheele discovered this substance, it appeared to have no use; it was in its infancy and

useless state, but having grown up to maturity, witness its powers, and see what endeavours to make it useful

[1] I am indebted to a friend for the following exquisite morsel: 'A short time after the publication of

Faraday's first researches in magnetoelectricity, he attended the meeting of the British Association at

Oxford, in 1832. On this occasion he was requested by some of the authorities to repeat the celebrated

experiment of eliciting a spark from a magnet, employing for this purpose the large magnet in the Ashmolean

Museum. To this he consented, and a large party assembled to witness the experiments, which, I need not say,

were perfectly successful. Whilst he was repeating them a dignitary of the University entered the room, and

addressing himself to Professor Daniell, who was standing near Faraday, inquired what was going on. The

Professor explained to him as popularly as possible this striking result of Faraday's great discovery. The Dean

listened with attention and looked earnestly at the brilliant spark, but a moment after he assumed a serious

countenance and shook his head; "I am sorry for it," said he, as he walked away; in the middle of the room he

stopped for a moment and repeated, "I am sorry for it:" then walking towards the door, when the handle was

in his hand he turned round and said, "Indeed I am sorry for it; it is putting new arms into the hands of the

incendiary." This occurred a short time after the papers had been filled with the doings of the hayrick burners.

An erroneous statement of what fell from the Dean's mouth was printed at the time in one of the Oxford

papers. He is there wrongly stated to have said, "It is putting new arms into the hands of the infidel."'

A point highly illustrative of the character of Faraday now comes into view. He gave an account of his

discovery of Magnetoelectricity in a letter to his friend M. Hachette, of Paris, who communicated the letter

to the Academy of Sciences. The letter was translated and published; and immediately afterwards two

distinguished Italian philosophers took up the subject, made numerous experiments, and published their

results before the complete memoirs of Faraday had met the public eye. This evidently irritated him. He

reprinted the paper of the learned Italians in the 'Philosophical Magazine,' accompanied by sharp critical

notes from himself. He also wrote a letter dated Dec. 1, 1832, to Gay Lussac, who was then one of the editors

of the 'Annales de Chimie,' in which he analysed the results of the Italian philosophers, pointing out their

errors, and defending himself from what he regarded as imputations on his character. The style of this letter is

unexceptionable, for Faraday could not write otherwise than as a gentleman; but the letter shows that had he

willed it he could have hit hard. We have heard much of Faraday's gentleness and sweetness and tenderness.

It is all true, but it is very incomplete. You cannot resolve a powerful nature into these elements, and

Faraday's character would have been less admirable than it was had it not embraced forces and tendencies to

which the silky adjectives 'gentle' and 'tender' would by no means apply. Underneath his sweetness and

gentleness was the heat of a volcano. He was a man of excitable and fiery nature; but through high

selfdiscipline he had converted the fire into a central glow and motive power of life, instead of permitting it

to waste itself in useless passion. 'He that is slow to anger,' saith the sage, 'is greater than the mighty, and he

that ruleth his own spirit than he that taketh a city.' Faraday was not slow to anger, but he completely ruled

As already intimated, Faraday had contributed many of his minor papersincluding his first analysis of

caustic limeto the 'Quarterly Journal of Science.' In 1832, he collected those papers and others together in a

'Papers of mine, published in octavo, in the "Quarterly Journal of Science," and elsewhere, since the time that

'Some, I think (at this date), are good; others moderate; and some bad. But I have put all into the volume,

because of the utility they have been of to meand none more than the badin pointing out to me in future,

'As I never looked over one of my papers a year after it was written without believing both in philosophy and

manner it could have been much better done, I still hope the collection may be of great use to me.

'None more than the bad!' This is a bit of Faraday's innermost nature; and as I read these words I am almost

constrained to retract what I have said regarding the fire and excitability of his character. But is he not all the

more admirable, through his ability to tone down and subdue that fire and that excitability, so as to render

himself able to write thus as a little child? I once took the liberty of censuring the conclusion of a letter of his

to the Dean of St. Paul's. He subscribed himself 'humbly yours,' and I objected to the adverb. 'Well, but,

Tyndall,' he said, 'I am humble; and still it would be a great mistake to think that I am not also proud.' This

duality ran through his character. A democrat in his defiance of all authority which unfairly limited his

freedom of thought, and still ready to stoop in reverence to all that was really worthy of reverence, in the

And here, as well as elsewhere, may be introduced a letter which bears upon this question of selfcontrol,

written long years subsequent to the period at which we have now arrived. I had been at Glasgow in 1855, at

a meeting of the British Association. On a certain day, I communicated a paper to the physical section, which

was followed by a brisk discussion. Men of great distinction took part in it, the late Dr. Whewell among the

number, and it waxed warm on both sides. I was by no means content with this discussion; and least of all,

with my own part in it. This discontent affected me for some days, during which I wrote to Faraday, giving

him no details, but expressing, in a general way, my dissatisfaction. I give the following extract from his

'My Dear Tyndall,These great meetings, of which I think very well altogether, advance science chiefly by

bringing scientific men together and making them to know and be friends with each other; and I am sorry

when that is not the effect in every part of their course. I know nothing except from what you tell me, for I

have not yet looked at the reports of the proceedings; but let me, as an old man, who ought by this time to

have profited by experience, say that when I was younger I found I often misinterpreted the intentions of

people, and found they did not mean what at the time I supposed they meant; and, further, that as a general

rule, it was better to be a little dull of apprehension where phrases seemed to imply pique, and quick in

perception when, on the contrary, they seemed to imply kindly feeling. The real truth never fails ultimately to

appear; and opposing parties, if wrong, are sooner convinced when replied to forbearingly, than when

overwhelmed. All I mean to say is, that it is better to be blind to the results of partisanship, and quick to see

good will. One has more happiness in oneself in endeavouring to follow the things that make for peace. You

can hardly imagine how often I have been heated in private when opposed, as I have thought, unjustly and

superciliously, and yet I have striven, and succeeded, I hope, in keeping down replies of the like kind. And I

know I have never lost by it. I would not say all this to you did I not esteem you as a true philosopher and

[1] Faraday would have been rejoiced to learn that, during its last meeting at Dundee, the British Association

illustrated in a striking manner the function which he here describes as its principal one. In my own case, a

brotherly welcome was everywhere manifested. In fact, the differences of really honourable and sane men are

I have already once used the word 'discomfort' in reference to the occasional state of Faraday's mind when

experimenting. It was to him a discomfort to reason upon data which admitted of doubt. He hated what he

called 'doubtful knowledge,' and ever tended either to transfer it into the region of undoubtful knowledge, or

of certain and definite ignorance. Pretence of all kinds, whether in life or in philosophy, was hateful to him.

He wished to know the reality of our nescience as well as of our science. 'Be one thing or the other,' he

seemed to say to an unproved hypothesis; 'come out as a solid truth, or disappear as a convicted lie.' After

making the great discovery which I have attempted to describe, a doubt seemed to beset him as regards the

identity of electricities. 'Is it right,' he seemed to ask, 'to call this agency which I have discovered electricity at

all? Are there perfectly conclusive grounds for believing that the electricity of the machine, the pile, the

gymnotus and torpedo, magnetoelectricity and thermoelectricity, are merely different manifestations of

one and the same agent?' To answer this question to his own satisfaction he formally reviewed the knowledge

of that day. He added to it new experiments of his own, and finally decided in favour of the 'Identity of

Electricities.' His paper upon this subject was read before the Royal Society on January 10 and 17, 1833.

After he had proved to his own satisfaction the identity of electricities, he tried to compare them

quantitatively together. The terms quantity and intensity, which Faraday constantly used, need a word of

explanation here. He might charge a single Leyden jar by twenty turns of his machine, or he might charge a

battery of ten jars by the same number of turns. The quantity in both cases would be sensibly the same, but

the intensity of the single jar would be the greatest, for here the electricity would be less diffused. Faraday

first satisfied himself that the needle of his galvanometer was caused to swing through the same arc by the

same quantity of machine electricity, whether it was condensed in a small battery or diffused over a large

one. Thus the electricity developed by thirty turns of his machine produced, under very variable conditions of

battery surface, the same deflection. Hence he inferred the possibility of comparing, as regards quantity,

electricities which differ greatly from each other in intensity. His object now is to compare frictional with

voltaic electricity. Moistening bibulous paper with the iodide of potassiuma favourite test of hisand

subjecting it to the action of machine electricity, he decomposed the iodide, and formed a brown spot where

the iodine was liberated. Then he immersed two wires, one of zinc, the other of platinum, each 1/13th of an

inch in diameter, to a depth of 5/8ths of an inch in acidulated water during eight beats of his watch, or 3/20ths

of a second; and found that the needle of his galvanometer swung through the same arc, and coloured his

moistened paper to the same extent, as thirty turns of his large electrical machine. Twentyeight turns of the

machine produced an effect distinctly less than that produced by his two wires. Now, the quantity of water

decomposed by the wires in this experiment totally eluded observation; it was immeasurably small; and still

that amount of decomposition involved the development of a quantity of electric force which, if applied in a

In his subsequent researches 'On the absolute Quantity of Electricity associated with the Particles or Atoms of

matter,' he endeavours to give an idea of the amount of electrical force involved in the decomposition of a

single grain of water. He is almost afraid to mention it, for he estimates it at 800,000 discharges of his large

Leyden battery. This, if concentrated in a single discharge, would be equal to a very great flash of lightning;

while the chemical action of a single grain of water on four grains of zinc would yield electricity equal in

quantity to a powerful thunderstorm. Thus his mind rises from the minute to the vast, expanding involuntarily

from the smallest laboratory fact till it embraces the largest and grandest natural phenomena.[1]

In reality, however, he is at this time only clearing his way, and he continues laboriously to clear it for some

time afterwards. He is digging the shaft, guided by that instinct towards the mineral lode which was to him a

rod of divination. 'Er riecht die Wahrheit,' said the lamented Kohlrausch, an eminent German, once in my

hearing: 'He smells the truth.' His eyes are now steadily fixed on this wonderful voltaic current, and he

On May 23, 1833, he read a paper before the Royal Society 'On a new Law of Electric Conduction.' He found

that, though the current passed through water, it did not pass through ice:why not, since they are one and

the same substance? Some years subsequently he answered this question by saying that the liquid condition

enables the molecule of water to turn round so as to place itself in the proper line of polarization, while the

rigidity of the solid condition prevents this arrangement. This polar arrangement must precede

decomposition, and decomposition is an accompaniment of conduction. He then passed on to other

substances; to oxides and chlorides, and iodides, and salts, and sulphurets, and found them all insulators when

solid, and conductors when fused. In all cases, moreover, except oneand this exception he thought might

be apparent onlyhe found the passage of the current across the fused compound to be accompanied by its

decomposition. Is then the act of decomposition essential to the act of conduction in these bodies? Even

recently this question was warmly contested. Faraday was very cautious latterly in expressing himself upon

this subject; but as a matter of fact he held that an infinitesimal quantity of electricity might pass through a

compound liquid without producing its decomposition. De la Rive, who has been a great worker on the

chemical phenomena of the pile, is very emphatic on the other side. Experiment, according to him and others,

establishes in the most conclusive manner that no trace of electricity can pass through a liquid compound

Faraday has now got fairly entangled amid the chemical phenomena of the pile, and here his previous training

under Davy must have been of the most important service to him. Why, he asks, should decomposition thus

take place?what force is it that wrenches the locked constituents of these compounds asunder? On the 20th

of June, 1833, he read a paper before the Royal Society 'On Electrochemical Decomposition,' in which he

seeks to answer these questions. The notion had been entertained that the poles, as they are called, of the

decomposing cell, or in other words the surfaces by which the current enters and quits the liquid, exercised

electric attractions upon the constituents of the liquid and tore them asunder. Faraday combats this notion

with extreme vigour. Litmus reveals, as you know, the action of an acid by turning red, turmeric reveals the

action of an alkali by turning brown. Sulphate of soda, you know, is a salt compounded of the alkali soda and

sulphuric acid. The voltaic current passing through a solution of this salt so decomposes it, that sulphuric acid

appears at one pole of the decomposing cell and alkali at the other. Faraday steeped a piece of litmus paper

and a piece of turmeric paper in a solution of sulphate of soda: placing each of them upon a separate plate of

glass, he connected them together by means of a string moistened with the same solution. He then attached

one of them to the positive conductor of an electric machine, and the other to the gaspipes of this building.

These he called his 'discharging train.' On turning the machine the electricity passed from paper to paper

through the string, which might be varied in length from a few inches to seventy feet without changing the

result. The first paper was reddened, declaring the presence of sulphuric acid; the second was browned,

declaring the presence of the alkali soda. The dissolved salt, therefore, arranged in this fashion, was

decomposed by the machine, exactly as it would have been by the voltaic current. When instead of using the

positive conductor he used the negative, the positions of the acid and alkali were reversed. Thus he satisfied

himself that chemical decomposition by the machine is obedient to the laws which rule decomposition by the

And now he gradually abolishes those socalled poles, to the attraction of which electric decomposition had

been ascribed. He connected a piece of turmeric paper moistened with the sulphate of soda with the positive

conductor of his machine; then he placed a metallic point in connection with his discharging train opposite

the moist paper, so that the electricity should discharge through the air towards the point. The turning of the

machine caused the corners of the piece of turmeric paper opposite to the point to turn brown, thus declaring

the presence of alkali. He changed the turmeric for litmus paper, and placed it, not in connection with his

conductor, but with his discharging train, a metallic point connected with the conductor being fixed at a

couple of inches from the paper; on turning the machine, acid was liberated at the edges and corners of the

litmus. He then placed a series of pointed pieces of paper, each separate piece being composed of two halves,

one of litmus and the other of turmeric paper, and all moistened with sulphate of soda, in the line of the

current from the machine. The pieces of paper were separated from each other by spaces of air. The machine

was turned; and it was always found that at the point where the electricity entered the paper, litmus was

reddened, and at the point where it quitted the paper, turmeric was browned. 'Here,' he urges, 'the poles are

entirely abandoned, but we have still electrochemical decomposition.' It is evident to him that instead of

being attracted by the poles, the bodies separated are ejected by the current. The effects thus obtained with

poles of air he also succeeded in obtaining with poles of water. The advance in Faraday's own ideas made at

this time is indicated by the word 'ejected.' He afterwards reiterates this view: the evolved substances are

Having abolished this idea of polar attraction, he proceeds to enunciate and develop a theory of his own. He

refers to Davy's celebrated Bakerian Lecture, given in 1806, which he says 'is almost entirely occupied in the

consideration of electrochemical decompositions.' The facts recorded in that lecture Faraday regards as of the

utmost value. But 'the mode of action by which the effects take place is stated very generally; so generally,

indeed, that probably a dozen precise schemes of electrochemical action might be drawn up, differing

It appears to me that these words might with justice be applied to Faraday's own researches at this time. They

furnish us with results of permanent value; but little help can be found in the theory advanced to account for

them. It would, perhaps, be more correct to say that the theory itself is hardly presentable in any tangible

form to the intellect. Faraday looks, and rightly looks, into the heart of the decomposing body itself; he sees,

and rightly sees, active within it the forces which produce the decomposition, and he rejects, and rightly

rejects, the notion of external attraction; but beyond the hypothesis of decompositions and recompositions,

enunciated and developed by Grothuss and Davy, he does not, I think, help us to any definite conception as to

how the force reaches the decomposing mass and acts within it. Nor, indeed, can this be done, until we know

Faraday conceives of that current as 'an axis of power having contrary forces exactly equal in amount in

opposite directions'; but this definition, though much quoted and circulated, teaches us nothing regarding the

current. An 'axis' here can only mean a direction; and what we want to be able to conceive of is, not the axis

along which the power acts, but the nature and mode of action of the power itself. He objects to the

vagueness of De la Rive; but the fact is, that both he and De la Rive labour under the same difficulty. Neither

wishes to commit himself to the notion of a current compounded of two electricities flowing in two opposite

directions: but the time had not come, nor is it yet come, for the displacement of this provisional fiction by

the true mechanical conception. Still, however indistinct the theoretic notions of Faraday at this time may be,

the facts which are rising before him and around him are leading him gradually, but surely, to results of

He had always some great object of research in view, but in the pursuit of it he frequently alighted on facts of

collateral interest, to examine which he sometimes turned aside from his direct course. Thus we find the

series of his researches on electrochemical decomposition interrupted by an inquiry into 'the power of metals

and other solids, to induce the combination of gaseous bodies.' This inquiry, which was received by the Royal

Society on Nov. 30, 1833, though not so important as those which precede and follow it, illustrates

throughout his strength as an experimenter. The power of spongy platinum to cause the combination of

oxygen and hydrogen had been discovered by Dobereiner in 1823, and had been applied by him in the

construction of his wellknown philosophic lamp. It was shown subsequently by Dulong and Thenard that

even a platinum wire, when perfectly cleansed, may be raised to incandescence by its action on a jet of cold

In his experiments on the decomposition of water, Faraday found that the positive platinum plate of the

decomposing cell possessed in an extraordinary degree the power of causing oxygen and hydrogen to

combine. He traced the cause of this to the perfect cleanness of the positive plate. Against it was liberated

oxygen, which, with the powerful affinity of the 'nascent state,' swept away all impurity from the surface

against which it was liberated. The bubbles of gas liberated on one of the platinum plates or wires of a

decomposing cell are always much smaller, and they rise in much more rapid succession than those from the

other. Knowing that oxygen is sixteen times heavier than hydrogen, I have more than once concluded, and, I

fear, led others into the error of concluding, that the smaller and more quickly rising bubbles must belong to

the lighter gas. The thing appeared so obvious that I did not give myself the trouble of looking at the battery,

which would at once have told me the nature of the gas. But Faraday would never have been satisfied with a

deduction if he could have reduced it to a fact. And he has taught me that the fact here is the direct reverse of

what I supposed it to be. The small bubbles are oxygen, and their smallness is due to the perfect cleanness of

the surface on which they are liberated. The hydrogen adhering to the other electrode swells into large

bubbles, which rise in much slower succession; but when the current is reversed, the hydrogen is liberated

[1] Buff finds the quantity of electricity associated with one milligramme of hydrogen in water to be equal to

45,480 charges of a Leyden jar, with a height of 480 millimetres, and a diameter of 160 millimetres. Weber

and Kohlrausch have calculated that, if the quantity of electricity associated with one milligramme of

hydrogen in water were diffused over a cloud at a height of 1000 metres above the earth, it would exert upon

an equal quantity of the opposite electricity at the earth's surface an attractive force of 2,268,000

In our conceptions and reasonings regarding the forces of nature, we perpetually make use of symbols which,

when they possess a high representative value, we dignify with the name of theories. Thus, prompted by

certain analogies, we ascribe electrical phenomena to the action of a peculiar fluid, sometimes flowing,

sometimes at rest. Such conceptions have their advantages and their disadvantages; they afford peaceful

lodging to the intellect for a time, but they also circumscribe it, and byandby, when the mind has grown

too large for its lodging, it often finds difficulty in breaking down the walls of what has become its prison

No man ever felt this tyranny of symbols more deeply than Faraday, and no man was ever more assiduous

than he to liberate himself from them, and the terms which suggested them. Calling Dr. Whewell to his aid in

1833, he endeavoured to displace by others all terms tainted by a foregone conclusion. His paper on

Electrochemical Decomposition, received by the Royal Society on January 9, 1834, opens with the proposal

of a new terminology. He would avoid the word 'current' if he could.[2] He does abandon the word 'poles' as

applied to the ends of a decomposing cell, because it suggests the idea of attraction, substituting for it the

perfectly natural term Electrodes. He applied the term Electrolyte to every substance which can be

decomposed by the current, and the act of decomposition he called Electrolysis. All these terms have become

current in science. He called the positive electrode the Anode, and the negative one the Cathode, but these

terms, though frequently used, have not enjoyed the same currency as the others. The terms Anion and

Cation, which he applied to the constituents of the decomposed electrolyte, and the term Ion, which included

Faraday now passes from terminology to research; he sees the necessity of quantitative determinations, and

seeks to supply himself with a measure of voltaic electricity. This he finds in the quantity of water

decomposed by the current. He tests this measure in all possible ways, to assure himself that no error can

arise from its employment. He places in the course of one and the same current a series of cells with

electrodes of different sizes, some of them plates of platinum, others merely platinum wires, and collects the

gas liberated on each distinct pair of electrodes. He finds the quantity of gas to be the same for all. Thus he

concludes that when the same quantity of electricity is caused to pass through a series of cells containing

acidulated water, the electrochemical action is independent of the size of the electrodes.[3] He next proves

that variations in intensity do not interfere with this equality of action. Whether his battery is charged with

strong acid or with weak; whether it consists of five pairs or of fifty pairs; in short, whatever be its source,

when the same current is sent through his series of cells the same amount of decomposition takes place in all.

He next assures himself that the strength or weakness of his dilute acid does not interfere with this law.

Sending the same current through a series of cells containing mixtures of sulphuric acid and water of different

strengths, he finds, however the proportion of acid to water might vary, the same amount of gas to be

collected in all the cells. A crowd of facts of this character forced upon Faraday's mind the conclusion that the

amount of electrochemical decomposition depends, not upon the size of the electrodes, not upon the

intensity of the current, not upon the strength of the solution, but solely upon the quantity of electricity which

passes through the cell. The quantity of electricity he concludes is proportional to the amount of chemical

action. On this law Faraday based the construction of his celebrated Voltameter, or Measure of Voltaic

But before he can apply this measure he must clear his ground of numerous possible sources of error. The

decomposition of his acidulated water is certainly a direct result of the current; but as the varied and

important researches of MM. Becquerel, De la Rive, and others had shown, there are also secondary actions

which may materially interfere with and complicate the pure action of the current. These actions may occur in

two ways: either the liberated ion may seize upon the electrode against which it is set free, forming a

chemical compound with that electrode; or it may seize upon the substance of the electrolyte itself, and thus

introduce into the circuit chemical actions over and above those due to the current. Faraday subjected these

secondary actions to an exhaustive examination. Instructed by his experiments, and rendered competent by

them to distinguish between primary and secondary results, he proceeds to establish the doctrine of 'Definite

Into the same circuit he introduced his voltameter, which consisted of a graduated tube filled with acidulated

water and provided with platinum plates for the decomposition of the water, and also a cell containing

chloride of tin. Experiments already referred to had taught him that this substance, though an insulator when

solid, is a conductor when fused, the passage of the current being always accompanied by the decomposition

of the chloride. He wished to ascertain what relation this decomposition bore to that of the water in his

Completing his circuit, he permitted the current to continue until 'a reasonable quantity of gas' was collected

in the voltameter. The circuit was then broken, and the quantity of tin liberated compared with the quantity of

gas. The weight of the former was 3.2 grains, that of the latter 0.49742 of a grain. Oxygen, as you know,

unites with hydrogen in the proportion of 8 to 1, to form water. Calling the equivalent, or as it is sometimes

called, the atomic weight of hydrogen 1, that of oxygen is 8; that of water is consequently 8 + 1 or 9. Now if

the quantity of water decomposed in Faraday's experiment be represented by the number 9, or in other words

by the equivalent of water, then the quantity of tin liberated from the fused chloride is found by an easy

calculation to be 57.9, which is almost exactly the chemical equivalent of tin. Thus both the water and the

chloride were broken up in proportions expressed by their respective equivalents. The amount of electric

force which wrenched asunder the constituents of the molecule of water was competent, and neither more nor

less than competent, to wrench asunder the constituents of the molecules of the chloride of tin. The fact is

typical. With the indications of his voltameter he compared the decompositions of other substances, both

singly and in series. He submitted his conclusions to numberless tests. He purposely introduced secondary

actions. He endeavoured to hamper the fulfilment of those laws which it was the intense desire of his mind to

see established. But from all these difficulties emerged the golden truth, that under every variety of

circumstances the decompositions of the voltaic current are as definite in their character as those chemical

combinations which gave birth to the atomic theory. This law of Electrochemical Decomposition ranks, in

[1] I copy these words from the printed abstract of a Friday evening lecture, given by myself, because they

remind me of Faraday's voice, responding to the utterance by an emphatic 'hear! hear!'Proceedings of the

[2] In 1838 he expresses himself thus:'The word current is so expressive in common language that when

applied in the consideration of electrical phenomena, we can hardly divest it sufficiently of its meaning, or

prevent our minds from being prejudiced by it.' Exp. Resear., vol. i. p. 515. ($ 1617.)

[3] This conclusion needs qualification. Faraday overlooked the part played by ozone.

In one of the public areas of the town of Como stands a statue with no inscription on its pedestal, save that of

a single name, 'Volta.' The bearer of that name occupies a place for ever memorable in the history of science.

To him we owe the discovery of the voltaic pile, to which for a brief interval we must now turn our attention.

The objects of scientific thought being the passionless laws and phenomena of external nature, one might

suppose that their investigation and discussion would be completely withdrawn from the region of the

feelings, and pursued by the cold dry light of the intellect alone. This, however, is not always the case. Man

carries his heart with him into all his works. You cannot separate the moral and emotional from the

intellectual; and thus it is that the discussion of a point of science may rise to the heat of a battlefield. The

fight between the rival optical theories of Emission and Undulation was of this fierce character; and scarcely

less fierce for many years was the contest as to the origin and maintenance of the power of the voltaic pile.

Volta himself supposed it to reside in the Contact of different metals. Here was exerted his 'Electromotive

force,' which tore the combined electricities asunder and drove them as currents in opposite directions. To

render the circulation of the current possible, it was necessary to connect the metals by a moist conductor; for

when any two metals were connected by a third, their relation to each other was such that a complete

neutralisation of the electric motion was the result. Volta's theory of metallic contact was so clear, so

beautiful, and apparently so complete, that the best intellects of Europe accepted it as the expression of

Volta himself knew nothing of the chemical phenomena of the pile; but as soon as these became known,

suggestions and intimations appeared that chemical action, and not metallic contact, might be the real source

of voltaic electricity. This idea was expressed by Fabroni in Italy, and by Wollaston in England. It was

developed and maintained by those 'admirable electricians,' Becquerel, of Paris, and De la Rive, of Geneva.

The Contact Theory, on the other hand, received its chief development and illustration in Germany. It was

long the scientific creed of the great chemists and natural philosophers of that country, and to the present hour

there may be some of them unable to liberate themselves from the fascination of their firstlove.

After the researches which I have endeavoured to place before you, it was impossible for Faraday to avoid

taking a side in this controversy. He did so in a paper 'On the Electricity of the Voltaic Pile,' received by the

Royal Society on the 7th of April, 1834. His position in the controversy might have been predicted. He saw

chemical effects going hand in hand with electrical effects, the one being proportional to the other; and, in the

paper now before us, he proved that when the former was excluded, the latter were sought for in vain. He

produced a current without metallic contact; he discovered liquids which, though competent to transmit the

feeblest currentscompetent therefore to allow the electricity of contact to flow through them if it were able

One of the very few experimental mistakes of Faraday occurred in this investigation. He thought that with a

single voltaic cell he had obtained the spark before the metals touched, but he subsequently discovered his

error. To enable the voltaic spark to pass through air before the terminals of the battery were united, it was

necessary to exalt the electromotive force of the battery by multiplying its elements; but all the elements

Faraday possessed were unequal to the task of urging the spark across the shortest measurable space of air.

Nor, indeed, could the action of the battery, the different metals of which were in contact with each other,

decide the point in question. Still, as regards the identity of electricities from various sources, it was at that

day of great importance to determine whether or not the voltaic current could jump, as a spark, across an

interval before contact. Faraday's friend, Mr. Gassiot, solved this problem. He erected a battery of 4000 cells,

and with it urged a stream of sparks from terminal to terminal, when separated from each other by a

The memoir on the 'Electricity of the Voltaic Pile,' published in 1834, appears to have produced but little

impression upon the supporters of the contact theory. These indeed were men of too great intellectual weight

and insight lightly to take up, or lightly to abandon a theory. Faraday therefore resumed the attack in a paper,

communicated to the Royal Society on the 6th of February, 1840. In this paper he hampered his antagonists

by a crowd of adverse experiments. He hung difficulty after difficulty about the neck of the contact theory,

until in its efforts to escape from his assaults it so changed its character as to become a thing totally different

from the theory proposed by Volta. The more persistently it was defended, however, the more clearly did it

show itself to be a congeries of devices, bearing the stamp of dialectic skill rather than of natural truth.

In conclusion, Faraday brought to bear upon it an argument which, had its full weight and purport been

understood at the time, would have instantly decided the controversy. 'The contact theory,' he urged, 'assumed

that a force which is able to overcome powerful resistance, as for instance that of the conductors, good or

bad, through which the current passes, and that again of the electrolytic action where bodies are decomposed

by it, can arise out of nothing; that, without any change in the acting matter, or the consumption of any

generating force, a current shall be produced which shall go on for ever against a constant resistance, or only

be stopped, as in the voltaic trough, by the ruins which its exertion has heaped up in its own course. This

would indeed be a creation of power, and is like no other force in nature. We have many processes by which

the form of the power may be so changed, that an apparent conversion of one into the other takes place. So

we can change chemical force into the electric current, or the current into chemical force. The beautiful

experiments of Seebeck and Peltier show the convertibility of heat and electricity; and others by Oersted and

myself show the convertibility of electricity and magnetism. But in no case, not even in those of the

Gymnotus and Torpedo, is there a pure creation or a production of power without a corresponding exhaustion

These words were published more than two years before either Mayer printed his brief but celebrated essay

on the Forces of Inorganic Nature, or Mr. Joule published his first famous experiments on the Mechanical

Value of Heat. They illustrate the fact that before any great scientific principle receives distinct enunciation

by individuals, it dwells more or less clearly in the general scientific mind. The intellectual plateau is already

high, and our discoverers are those who, like peaks above the plateau, rise a little above the general level of

But many years prior even to the foregoing utterance of Faraday, a similar argument had been employed. I

quote here with equal pleasure and admiration the following passage written by Dr. Roget so far back as

1829. Speaking of the contact theory, he says: 'If there could exist a power having the property ascribed to

it by the hypothesis, namely, that of giving continual impulse to a fluid in one constant direction, without

being exhausted by its own action, it would differ essentially from all the known powers in nature. All the

powers and sources of motion with the operation of which we are acquainted, when producing these peculiar

effects, are expended in the same proportion as those effects are produced; and hence arises the impossibility

of obtaining by their agency a perpetual effect; or in other words a perpetual motion. But the electromotive

force, ascribed by Volta to the metals, when in contact, is a force which, as long as a free course is allowed to

the electricity it sets in motion, is never expended, and continues to be excited with undiminished power in

the production of a neverceasing effect. Against the truth of such a supposition the probabilities are all but

infinite.' When this argument, which he employed independently, had clearly fixed itself in his mind, Faraday

never cared to experiment further on the source of electricity in the voltaic pile. The argument appeared to

him 'to remove the foundation itself of the contact theory,' and he afterwards let it crumble down in peace.[1]

[1] To account for the electric current, which was really the core of the whole discussion, Faraday

demonstrated the impotence of the Contact Theory as then enunciated and defended. Still, it is certain that

two different metals, when brought into contact, charge themselves, the one with positive and the other with

negative electricity. I had the pleasure of going over this ground with Kohlrausch in 1849, and his

experiments left no doubt upon my mind that the contact electricity of Volta was a reality, though it could

produce no current. With one of the beautiful instruments devised by himself, Sir William Thomson has

rendered this point capable of sure and easy demonstration; and he and others now hold what may be called a

contact theory, which, while it takes into account the action of the metals, also embraces the chemical

phenomena of the circuit. Helmholtz, I believe, was the first to give the contact theory this new form, in his

Researches on frictional electricity: induction: conduction: specific inductive capacity: theory of contiguous

The burst of power which had filled the four preceding years with an amount of experimental work

unparalleled in the history of science partially subsided in 1835, and the only scientific paper contributed by

Faraday in that year was a comparatively unimportant one, 'On an improved Form of the Voltaic Battery.' He

brooded for a time: his experiments on electrolysis had long filled his mind; he looked, as already stated, into

the very heart of the electrolyte, endeavouring to render the play of its atoms visible to his mental eye. He had

no doubt that in this case what is called 'the electric current' was propagated from particle to particle of the

electrolyte; he accepted the doctrine of decomposition and recomposition which, according to Grothuss and

Davy, ran from electrode to electrode. And the thought impressed him more and more that ordinary electric

induction was also transmitted and sustained by the action of 'contiguous particles.'

His first great paper on frictional electricity was sent to the Royal Society on November 30, 1837. We here

find him face to face with an idea which beset his mind throughout his whole subsequent life,the idea of

action at a distance. It perplexed and bewildered him. In his attempts to get rid of this perplexity, he was often

unconsciously rebelling against the limitations of the intellect itself. He loved to quote Newton upon this

point; over and over again he introduces his memorable words, 'That gravity should be innate, inherent, and

essential to matter, so that one body may act upon another at a distance through a vacuum and without the

mediation of anything else, by and through which this action and force may be conveyed from one to another,

is to me so great an absurdity, that I believe no man who has in philosophical matters a competent faculty of

thinking, can ever fall into it. Gravity must be caused by an agent acting constantly according to certain laws;

but whether this agent be material or immaterial, I have left to the consideration of my readers.'[1]

Faraday does not see the same difficulty in his contiguous particles. And yet, by transferring the conception

from masses to particles, we simply lessen size and distance, but we do not alter the quality of the conception.

Whatever difficulty the mind experiences in conceiving of action at sensible distances, besets it also when it

attempts to conceive of action at insensible distances. Still the investigation of the point whether electric and

magnetic effects were wrought out through the intervention of contiguous particles or not, had a physical

interest altogether apart from the metaphysical difficulty. Faraday grapples with the subject experimentally.

By simple intuition he sees that action at a distance must be exerted in straight lines. Gravity, he knows, will

not turn a corner, but exerts its pull along a right line; hence his aim and effort to ascertain whether electric

action ever takes place in curved lines. This once proved, it would follow that the action is carried on by

means of a medium surrounding the electrified bodies. His experiments in 1837 reduced, in his opinion, this

point of demonstration. He then found that he could electrify, by induction, an insulated sphere placed

completely in the shadow of a body which screened it from direct action. He pictured the lines of electric

force bending round the edges of the screen, and reuniting on the other side of it; and he proved that in many

cases the augmentation of the distance between his insulated sphere and the inducing body, instead of

lessening, increased the charge of the sphere. This he ascribed to the coalescence of the lines of electric force

Faraday's theoretic views on this subject have not received general acceptance, but they drove him to

experiment, and experiment with him was always prolific of results. By suitable arrangements he placed a

metallic sphere in the middle of a large hollow sphere, leaving a space of something more than half an inch

between them. The interior sphere was insulated, the external one uninsulated. To the former he

communicated a definite charge of electricity. It acted by induction upon the concave surface of the latter,

and he examined how this act of induction was effected by placing insulators of various kinds between the

two spheres. He tried gases, liquids, and solids, but the solids alone gave him positive results. He constructed

two instruments of the foregoing description, equal in size and similar in form. The interior sphere of each

communicated with the external air by a brass stem ending in a knob. The apparatus was virtually a Leyden

jar, the two coatings of which were the two spheres, with a thick and variable insulator between them. The

amount of charge in each jar was determined by bringing a proofplane into contact with its knob and

measuring by a torsion balance the charge taken away. He first charged one of his instruments, and then

dividing the charge with the other, found that when air intervened in both cases the charge was equally

divided. But when shellac, sulphur, or spermaceti was interposed between the two spheres of one jar, while

air occupied this interval in the other, then he found that the instrument occupied by the 'solid dielectric' takes

more than half the original charge. A portion of the charge was absorbed by the dielectric itself. The

electricity took time to penetrate the dielectric. Immediately after the discharge of the apparatus, no trace of

electricity was found upon its knob. But after a time electricity was found there, the charge having gradually

returned from the dielectric in which it had been lodged. Different insulators possess this power of permitting

the charge to enter them in different degrees. Faraday figured their particles as polarized, and he concluded

that the force of induction is propagated from particle to particle of the dielectric from the inner sphere to the

outer one. This power of propagation possessed by insulators he called their 'Specific Inductive Capacity.'

Faraday visualizes with the utmost clearness the state of his contiguous particles; one after another they

become charged, each succeeding particle depending for its charge upon its predecessor. And now he seeks to

break down the wall of partition between conductors and insulators. 'Can we not,' he says, 'by a gradual chain

of association carry up discharge from its occurrence in air through spermaceti and water, to solutions, and

then on to chlorides, oxides, and metals, without any essential change in its character?' Even copper, he urges,

offers a resistance to the transmission of electricity. The action of its particles differs from those of an

insulator only in degree. They are charged like the particles of the insulator, but they discharge with greater

ease and rapidity; and this rapidity of molecular discharge is what we call conduction. Conduction then is

always preceded by atomic induction; and when, through some quality of the body which Faraday does not

define, the atomic discharge is rendered slow and difficult, conduction passes into insulation.

Though they are often obscure, a fine vein of philosophic thought runs through those investigations. The

mind of the philosopher dwells amid those agencies which underlie the visible phenomena of Induction and

Conduction; and he tries by the strong light of his imagination to see the very molecules of his dielectrics. It

would, however, be easy to criticise these researches, easy to show the looseness, and sometimes the

inaccuracy, of the phraseology employed; but this critical spirit will get little good out of Faraday. Rather let

those who ponder his works seek to realise the object he set before him, not permitting his occasional

vagueness to interfere with their appreciation of his speculations. We may see the ripples, and eddies, and

vortices of a flowing stream, without being able to resolve all these motions into their constituent elements;

and so it sometimes strikes me that Faraday clearly saw the play of fluids and ethers and atoms, though his

previous training did not enable him to resolve what he saw into its constituents, or describe it in a manner

satisfactory to a mind versed in mechanics. And then again occur, I confess, dark sayings, difficult to be

understood, which disturb my confidence in this conclusion. It must, however, always be remembered that he

works at the very boundaries of our knowledge, and that his mind habitually dwells in the 'boundless

In the researches now under review the ratio of speculation and reasoning to experiment is far higher than in

any of Faraday's previous works. Amid much that is entangled and dark we have flashes of wondrous insight

and utterances which seem less the product of reasoning than of revelation. I will confine myself here to one

example of this divining power. By his most ingenious device of a rapidly rotating mirror, Wheatstone had

proved that electricity required time to pass through a wire, the current reaching the middle of the wire later

than its two ends. 'If,' says Faraday, 'the two ends of the wire in Professor Wheatstone's experiments were

immediately connected with two large insulated metallic surfaces exposed to the air, so that the primary act

of induction, after making the contact for discharge, might be in part removed from the internal portion of the

wire at the first instance, and disposed for the moment on its surface jointly with the air and surrounding

conductors, then I venture to anticipate that the middle spark would be more retarded than before. And if

those two plates were the inner and outer coatings of a large jar or Leyden battery, then the retardation of the

spark would be much greater.' This was only a prediction, for the experiment was not made.[2] Sixteen years

subsequently, however, the proper conditions came into play, and Faraday was able to show that the

observations of Werner Siemens, and Latimer Clark, on subterraneous and submarine wires were

illustrations, on a grand scale, of the principle which he had enunciated in 1838. The wires and the

surrounding water act as a Leyden jar, and the retardation of the current predicted by Faraday manifests itself

The meaning of Faraday in these memoirs on Induction and Conduction is, as I have said, by no means

always clear; and the difficulty will be most felt by those who are best trained in ordinary theoretic

conceptions. He does not know the reader's needs, and he therefore does not meet them. For instance he

speaks over and over again of the impossibility of charging a body with one electricity, though the

impossibility is by no means evident. The key to the difficulty is this. He looks upon every insulated

conductor as the inner coating of a Leyden jar. An insulated sphere in the middle of a room is to his mind

such a coating; the walls are the outer coating, while the air between both is the insulator, across which the

charge acts by induction. Without this reaction of the walls upon the sphere you could no more, according to

Faraday, charge it with electricity than you could charge a Leyden jar, if its outer coating were removed.

Distance with him is immaterial. His strength as a generalizer enables him to dissolve the idea of magnitude;

and if you abolish the walls of the roomeven the earth itselfhe would make the sun and planets the outer

coating of his jar. I dare not contend that Faraday in these memoirs made all his theoretic positions good. But

a pure vein of philosophy runs through these writings; while his experiments and reasonings on the forms and

[2] Had Sir Charles Wheatstone been induced to resume his measurements, varying the substances through

which, and the conditions under which, the current is propagated, he might have rendered great service to

The last of these memoirs was dated from the Royal Institution in June, 1838. It concludes the first volume of

his 'Experimental Researches on Electricity.' In 1840, as already stated, he made his final assault on the

Contact Theory, from which it never recovered.[1] He was now feeling the effects of the mental strain to

which he had been subjected for so many years. During these years he repeatedly broke down. His wife alone

witnessed the extent of his prostration, and to her loving care we, and the world, are indebted for the

enjoyment of his presence here so long. He found occasional relief in a theatre. He frequently quitted London

and went to Brighton and elsewhere, always choosing a situation which commanded a view of the sea, or of

some other pleasant horizon, where he could sit and gaze and feel the gradual revival of the faith that

But very often for some days after his removal to the country, he would be unable to do more than sit at a

In 1841, his state became more serious than it had ever been before. A published letter to Mr. Richard Taylor,

dated March 11, 1843, contains an allusion to his previous condition. 'You are aware,' he says, 'that

considerations regarding health have prevented me from working or reading on science for the last two years.'

This, at one period or another of their lives, seems to be the fate of most great investigators. They do not

know the limits of their constitutional strength until they have transgressed them. It is, perhaps, right that they

should transgress them, in order to ascertain where they lie. Faraday, however, though he went far towards it,

did not push his transgression beyond his power of restitution. In 1841 Mrs. Faraday and he went to

Switzerland, under the affectionate charge of her brother, Mr. George Barnard, the artist. This time of

suffering throws fresh light upon his character. I have said that sweetness and gentleness were not its only

constituents; that he was also fiery and strong. At the time now referred to, his fire was low and his strength

distilled away; but the residue of his life was neither irritability nor discontent. He was unfit to mingle in

society, for conversation was a pain to him; but let us observe the great Manchild when alone. He is at the

village of Interlaken, enjoying Jungfrau sunsets, and at times watching the Swiss nailers making their nails.

He keeps a little journal, in which he describes the process of nailmaking, and incidentally throws a luminous

'August 2, 1841.Clout nailmaking goes on here rather considerably, and is a very neat and pretty operation

to observe. I love a smith's shop and anything relating to smithery. My father was a smith.'

From Interlaken he went to the Falls of the Giessbach, on the pleasant lake of Brientz. And here we have him

watching the shoot of the cataract down its series of precipices. It is shattered into foam at the base of each,

and tossed by its own recoil as waterdust through the air. The sun is at his back, shining on the drifting

'August 12, 1841.Today every fall was foaming from the abundance of water, and the current of wind

brought down by it was in some places too strong to stand against. The sun shone brightly, and the rainbows

seen from various points were very beautiful. One at the bottom of a fine but furious fall was very

pleasant,there it remained motionless, whilst the gusts and clouds of spray swept furiously across its place

and were dashed against the rock. It looked like a spirit strong in faith and steadfast in the midst of the storm

of passions sweeping across it, and though it might fade and revive, still it held on to the rock as in hope and

giving hope. And the very drops, which in the whirlwind of their fury seemed as if they would carry all away,

But we must quit the man and go on to the discoverer: we shall return for a brief space to his company

byandby. Carry your thoughts back to his last experiments, and see him endeavouring to prove that

induction is due to the action of contiguous particles. He knew that polarized light was a most subtle and

delicate investigator of molecular condition. He used it in 1834 in exploring his electrolytes, and he tried it in

1838 upon his dielectrics. At that time he coated two opposite faces of a glass cube with tinfoil, connected

one coating with his powerful electric machine and the other with the earth, and examined by polarized light

the condition of the glass when thus subjected to strong electric influence. He failed to obtain any effect; still

he was persuaded an action existed, and required only suitable means to call it forth.

After his return from Switzerland he was beset by these thoughts; they were more inspired than logical: but

he resorted to magnets and proved his inspiration true. His dislike of 'doubtful knowledge' and his efforts to

liberate his mind from the thraldom of hypotheses have been already referred to. Still this rebel against theory

was incessantly theorising himself. His principal researches are all connected by an undercurrent of

speculation. Theoretic ideas were the very sap of his intellectthe source from which all his strength as an

experimenter was derived. While once sauntering with him through the Crystal Palace, at Sydenham, I asked

him what directed his attention to the magnetization of light. It was his theoretic notions. He had certain

views regarding the unity and convertibility of natural forces; certain ideas regarding the vibrations of light

and their relations to the lines of magnetic force; these views and ideas drove him to investigation. And so it

must always be: the great experimentalist must ever be the habitual theorist, whether or not he gives to his

Faraday, you have been informed, endeavoured to improve the manufacture of glass for optical purposes. But

though he produced a heavy glass of great refractive power, its value to optics did not repay him for the pains

and labour bestowed on it. Now, however, we reach a result established by means of this same heavy glass,

In November, 1845, he announced his discovery of the 'Magnetization of Light and the Illumination of the

Lines of Magnetic Force.' This title provoked comment at the time, and caused misapprehension. He

therefore added an explanatory note; but the note left his meaning as entangled as before. In fact Faraday had

notions regarding the magnetization of light which were peculiar to himself, and untranslatable into the

scientific language of the time. Probably no other philosopher of his day would have employed the phrases

just quoted as appropriate to the discovery announced in 1845. But Faraday was more than a philosopher; he

was a prophet, and often wrought by an inspiration to be understood by sympathy alone. The prophetic

element in his character occasionally coloured, and even injured, the utterance of the man of science; but

subtracting that element, though you might have conferred on him intellectual symmetry, you would have

But let us pass from the label of this casket to the jewel it contains. 'I have long,' he says, 'held an opinion,

almost amounting to conviction, in common, I believe, with many other lovers of natural knowledge, that the

various forms under which the forces of matter are made manifest have one common origin; in other words,

are so directly related and mutually dependent, that they are convertible, as it were, into one another, and

possess equivalents of power in their action.... This strong persuasion,' he adds, 'extended to the powers of

light.' And then he examines the action of magnets upon light. From conversation with him and Anderson, I

should infer that the labour preceding this discovery was very great. The world knows little of the toil of the

discoverer. It sees the climber jubilant on the mountain top, but does not know the labour expended in

reaching it. Probably hundreds of experiments had been made on transparent crystals before he thought of

testing his heavy glass. Here is his own clear and simple description of the result of his first experiment with

this substance:'A piece of this glass, about two inches square, and 0.5 of an inch thick, having flat and

polished edges, was placed as a diamagnetic[1] between the poles (not as yet magnetized by the electric

current), so that the polarized ray should pass through its length; the glass acted as air, water, or any other

transparent substance would do; and if the eyepiece were previously turned into such a position that the

polarized ray was extinguished, or rather the image produced by it rendered invisible, then the introduction of

the glass made no alteration in this respect. In this state of circumstances, the force of the electromagnet was

developed by sending an electric current through its coils, and immediately the image of the lampflame

became visible and continued so as long as the arrangement continued magnetic. On stopping the electric

current, and so causing the magnetic force to cease, the light instantly disappeared. These phenomena could

be renewed at pleasure, at any instant of time, and upon any occasion, showing a perfect dependence of cause

In a beam of ordinary light the particles of the luminiferous ether vibrate in all directions perpendicular to the

line of progression; by the act of polarization, performed here by Faraday, all oscillations but those parallel to

a certain plane are eliminated. When the plane of vibration of the polarizer coincides with that of the

analyzer, a portion of the beam passes through both; but when these two planes are at right angles to each

other, the beam is extinguished. If by any means, while the polarizer and analyzer remain thus crossed, the

plane of vibration of the polarized beam between them could be changed, then the light would be, in part at

least, transmitted. In Faraday's experiment this was accomplished. His magnet turned the plane of

polarization of the beam through a certain angle, and thus enabled it to get through the analyzer; so that 'the

magnetization of light and the illumination of the magnetic lines of force' becomes, when expressed in the

To him, as to all true philosophers, the main value of a fact was its position and suggestiveness in the general

sequence of scientific truth. Hence, having established the existence of a phenomenon, his habit was to look

at it from all possible points of view, and to develop its relationship to other phenomena. He proved that the

direction of the rotation depends upon the polarity of his magnet; being reversed when the magnetic poles are

reversed. He showed that when a polarized ray passed through his heavy glass in a direction parallel to the

magnetic lines of force, the rotation is a maximum, and that when the direction of the ray is at right angles to

the lines of force, there is no rotation at all. He also proved that the amount of the rotation is proportional to

the length of the diamagnetic through which the ray passes. He operated with liquids and solutions. Of

aqueous solutions he tried 150 and more, and found the power in all of them. He then examined gases; but

here all his efforts to produce any sensible action upon the polarized beam were ineffectual. He then passed

from magnets to currents, enclosing bars of heavy glass, and tubes containing liquids and aqueous solutions

within an electromagnetic helix. A current sent through the helix caused the plane of polarization to rotate,

and always in the direction of the current. The rotation was reversed when the current was reversed. In the

case of magnets, he observed a gradual, though quick, ascent of the transmitted beam from a state of darkness

to its maximum brilliancy, when the magnet was excited. In the case of currents, the beam attained at once its

maximum. This he showed to be due to the time required by the iron of the electromagnet to assume its full

magnetic power, which time vanishes when a current, without iron, is employed. 'In this experiment,' he says,

'we may, I think, justly say that a ray of light is electrified, and the electric forces illuminated.' In the helix, as

with the magnets, he submitted air to magnetic influence 'carefully and anxiously,' but could not discover any

Many substances possess the power of turning the plane of polarization without the intervention of

magnetism. Oil of turpentine and quartz are examples; but Faraday showed that, while in one direction, that

is, across the lines of magnetic force, his rotation is zero, augmenting gradually from this until it attains its

maximum, when the direction of the ray is parallel to the lines of force; in the oil of turpentine the rotation is

independent of the direction of the ray. But he showed that a still more profound distinction exists between

the magnetic rotation and the natural one. I will try to explain how. Suppose a tube with glass ends containing

oil of turpentine to be placed north and south. Fixing the eye at the south end of the tube, let a polarized beam

be sent through it from the north. To the observer in this position the rotation of the plane of polarization, by

the turpentine, is righthanded. Let the eye be placed at the north end of the tube, and a beam be sent through

it from the south; the rotation is still righthanded. Not so, however, when a bar of heavy glass is subjected to

the action of an electric current. In this case if, in the first position of the eye, the rotation be righthanded, in

the second position it is lefthanded. These considerations make it manifest that if a polarized beam, after

having passed through the oil of turpentine in its natural state, could by any means be reflected back through

the liquid, the rotation impressed upon the direct beam would be exactly neutralized by that impressed upon

the reflected one. Not so with the induced magnetic effect. Here it is manifest that the rotation would be

doubled by the act of reflection. Hence Faraday concludes that the particles of the oil of turpentine which

rotate by virtue of their natural force, and those which rotate in virtue of the induced force, cannot be in the

same condition. The same remark applies to all bodies which possess a natural power of rotating the plane of

And then he proceeded with exquisite skill and insight to take advantage of this conclusion. He silvered the

ends of his piece of heavy glass, leaving, however, a narrow portion parallel to two edges diagonally opposed

to each other unsilvered. He then sent his beam through this uncovered portion, and by suitably inclining his

glass caused the beam within it to reach his eye first direct, and then after two, four, and six reflections. These

corresponded to the passage of the ray once, three times, five times, and seven times through the glass. He

thus established with numerical accuracy the exact proportionality of the rotation to the distance traversed by

the polarized beam. Thus in one series of experiments where the rotation required by the direct beam was

12degrees, that acquired by three passages through the glass was 36degrees, while that acquired by five

passages was 60degrees. But even when this method of magnifying was applied, he failed with various solid

substances to obtain any effect; and in the case of air, though he employed to the utmost the power which

these repeated reflections placed in his hands, he failed to produce the slightest sensible rotation.

These failures of Faraday to obtain the effect with gases seem to indicate the true seat of the phenomenon.

The luminiferous ether surrounds and is influenced by the ultimate particles of matter. The symmetry of the

one involves that of the other. Thus, if the molecules of a crystal be perfectly symmetrical round any line

through the crystal, we may safely conclude that a ray will pass along this line as through ordinary glass. It

will not be doubly refracted. From the symmetry of the liquid figures, known to be produced in the planes of

freezing, when radiant heat is sent through ice, we may safely infer symmetry of aggregation, and hence

conclude that the line perpendicular to the planes of freezing is a line of no double refraction; that it is, in

fact, the optic axis of the crystal. The same remark applies to the line joining the opposite blunt angles of a

crystal of Iceland spar. The arrangement of the molecules round this line being symmetrical, the condition of

the ether depending upon these molecules shares their symmetry; and there is, therefore, no reason why the

wavelength should alter with the alteration of the azimuth round this line. Annealed glass has its molecules

symmetrically arranged round every line that can be drawn through it; hence it is not doubly refractive. But

let the substance be either squeezed or strained in one direction, the molecular symmetry, and with it the

symmetry of the ether, is immediately destroyed and the glass becomes doubly refractive. Unequal heating

produces the same effect. Thus mechanical strains reveal themselves by optical effects; and there is little

doubt that in Faraday's experiment it is the magnetic strain that produces the rotation of the plane of

[1] 'By a diamagnetic,' says Faraday, 'I mean a body through which lines of magnetic force are passing, and

which does not by their action assume the usual magnetic state of iron or loadstone.' Faraday subsequently

used this term in a different sense from that here given, as will immediately appear.

[2] The power of double refraction conferred on the centre of a glass rod, when it is caused to sound the

fundamental note due to its longitudinal vibration, and the absence of the same power in the case of vibrating

air (enclosed in a glass organpipe), seems to be analogous to the presence and absence of Faraday's effect in

Faraday never, to my knowledge, attempted to give, even in conversation, a picture of the molecular

condition of his heavy glass when subjected to magnetic influence. In a mathematical investigation of the

subject, published in the Proceedings of the Royal Society for 1856, Sir William Thomson arrives at the

Faraday's next great step in discovery was announced in a memoir on the 'Magnetic Condition of all matter,'

communicated to the Royal Society on December 18, 1845. One great source of his success was the

employment of extraordinary power. As already stated, he never accepted a negative answer to an experiment

until he had brought to bear upon it all the force at his command. He had over and over again tried steel

magnets and ordinary electromagnets on various substances, but without detecting anything different from

the ordinary attraction exhibited by a few of them. Stronger coercion, however, developed a new action.

Before the pole of an electromagnet, he suspended a fragment of his famous heavy glass; and observed that

when the magnet was powerfully excited the glass fairly retreated from the pole. It was a clear case of

magnetic repulsion. He then suspended a bar of the glass between two poles; the bar retreated when the poles

were excited, and set its length equatorially or at right angles to the line joining them. When an ordinary

magnetic body was similarly suspended, it always set axially, that is, from pole to pole.

Faraday called those bodies which were repelled by the poles of a magnet, diamagnetic bodies; using this

term in a sense different from that in which he employed it in his memoir on the magnetization of light. The

term magnetic he reserved for bodies which exhibited the ordinary attraction. He afterwards employed the

term magnetic to cover the whole phenomena of attraction and repulsion, and used the word paramagnetic to

Isolated observations by Brugmanns, Becquerel, Le Baillif, Saigy, and Seebeck had indicated the existence of

a repulsive force exercised by the magnet on two or three substances; but these observations, which were

unknown to Faraday, had been permitted to remain without extension or examination. Having laid hold of the

fact of repulsion, Faraday immediately expanded and multiplied it. He subjected bodies of the most varied

qualities to the action of his magnet:mineral salts, acids, alkalis, ethers, alcohols, aqueous solutions, glass,

phosphorus, resins, oils, essences, vegetable and animal tissues, and found them all amenable to magnetic

influence. No known solid or liquid proved insensible to the magnetic power when developed in sufficient

strength. All the tissues of the human body, the bloodthough it contains iron included, were proved to

be diamagnetic. So that if you could suspend a man between the poles of a magnet, his extremities would

Soon after he had commenced his researches on diamagnetism, Faraday noticed a remarkable phenomenon

which first crossed my own path in the following way: In the year 1849, while working in the cabinet of my

friend, Professor Knoblauch, of Marburg, I suspended a small copper coin between the poles of an

electromagnet. On exciting the magnet, the coin moved towards the poles and then suddenly stopped, as if it

had struck against a cushion. On breaking the circuit, the coin was repelled, the revulsion being so violent as

to cause it to spin several times round its axis of suspension. A Silbergroschen similarly suspended

exhibited the same deportment. For a moment I thought this a new discovery; but on looking over the

literature of the subject, it appeared that Faraday had observed, multiplied, and explained the same effect

during his researches on diamagnetism. His explanation was based upon his own great discovery of

magnetoelectric currents. The effect is a most singular one. A weight of several pounds of copper may be

set spinning between the electromagnetic poles; the excitement of the magnet instantly stops the rotation.

Though nothing is apparent to the eye, the copper, if moved in the excited magnetic field, appears to move

through a viscous fluid; while, when a flat piece of the metal is caused to pass to and fro like a saw between

the poles, the sawing of the magnetic field resembles the cutting through of cheese or butter.[1] This virtual

friction of the magnetic field is so strong, that copper, by its rapid rotation between the poles, might probably

be fused. We may easily dismiss this experiment by saying that the heat is due to the electric currents excited

in the copper. But so long as we are unable to reply to the question, 'What is an electric current?' the

explanation is only provisional. For my own part, I look with profound interest and hope on the strange action

Faraday's thoughts ran intuitively into experimental combinations, so that subjects whose capacity for

experimental treatment would, to ordinary minds, seem to be exhausted in a moment, were shown by him to

be all but inexhaustible. He has now an object in view, the first step towards which is the proof that the

principle of Archimedes is true of magnetism. He forms magnetic solutions of various degrees of strength,

places them between the poles of his magnet, and suspends in the solutions various magnetic bodies. He

proves that when the solution is stronger than the body plunged in it, the body, though magnetic, is repelled;

and when an elongated piece of it is surrounded by the solution, it sets, like a diamagnetic body, equatorially

between the excited poles. The same body when suspended in a solution of weaker magnetic power than

And now theoretic questions rush in upon him. Is this new force a true repulsion, or is it merely a differential

attraction? Might not the apparent repulsion of diamagnetic bodies be really due to the greater attraction of

the medium by which they are surrounded? He tries the rarefaction of air, but finds the effect insensible. He is

averse to ascribing a capacity of attraction to space, or to any hypothetical medium supposed to fill space. He

therefore inclines, but still with caution, to the opinion that the action of a magnet upon bismuth is a true and

absolute repulsion, and not merely the result of differential attraction. And then he clearly states a theoretic

view sufficient to account for the phenomena. 'Theoretically,' he says, 'an explanation of the movements of

the diamagnetic bodies, and all the dynamic phenomena consequent upon the action of magnets upon them,

might be offered in the supposition that magnetic induction caused in them a contrary state to that which it

produced in ordinary matter.' That is to say, while in ordinary magnetic influence the exciting pole excites

adjacent to itself the contrary magnetism, in diamagnetic bodies the adjacent magnetism is the same as that of

the exciting pole. This theory of reversed polarity, however, does not appear to have ever laid deep hold of

Faraday's mind; and his own experiments failed to give any evidence of its truth. He therefore subsequently

He then entered a new, though related field of inquiry. Having dealt with the metals and their compounds,

and having classified all of them that came within the range of his observation under the two heads magnetic

and diamagnetic, he began the investigation of the phenomena presented by crystals when subjected to

magnetic power. This action of crystals had been in part theoretically predicted by Poisson,[2] and actually

discovered by Plucker, whose beautiful results, at the period which we have now reached, profoundly

interested all scientific men. Faraday had been frequently puzzled by the deportment of bismuth, a highly

crystalline metal. Sometimes elongated masses of the substance refused to set equatorially, sometimes they

set persistently oblique, and sometimes even, like a magnetic body, from pole to pole.

'The effect,' he says, 'occurs at a single pole; and it is then striking to observe a long piece of a substance so

diamagnetic as bismuth repelled, and yet at the same moment set round with force, axially, or end on, as a

piece of magnetic substance would do.' The effect perplexed him; and in his efforts to release himself from

this perplexity, no feature of this new manifestation of force escaped his attention. His experiments are

I have worked long myself at magnecrystallic action, amid all the light of Faraday's and Plucker's

researches. The papers now before me were objects of daily and nightly study with me eighteen or nineteen

years ago; but even now, though their perusal is but the last of a series of repetitions, they astonish me. Every

circumstance connected with the subject; every shade of deportment; every variation in the energy of the

action; almost every application which could possibly be made of magnetism to bring out in detail the

character of this new force, is minutely described. The field is swept clean, and hardly anything experimental

is left for the gleaner. The phenomena, he concludes, are altogether different from those of magnetism or

diamagnetism: they would appear, in fact, to present to us 'a new force, or a new form of force, in the

molecules of matter,' which, for convenience sake, he designates by a new word, as 'the magnecrystallic

He looks at the crystal acted upon by the magnet. From its mass he passes, in idea, to its atoms, and he asks

himself whether the power which can thus seize upon the crystalline molecules, after they have been fixed in

their proper positions by crystallizing force, may not, when they are free, be able to determine their

arrangement? He, therefore, liberates the atoms by fusing the bismuth. He places the fused substance between

the poles of an electromagnet, powerfully excited; but he fails to detect any action. I think it cannot be

doubted that an action is exerted here, that a true cause comes into play; but its magnitude is not such as

sensibly to interfere with the force of crystallization, which, in comparison with the diamagnetic force, is

enormous. 'Perhaps,' adds Faraday, 'if a longer time were allowed, and a permanent magnet used, a better

result might be obtained. I had built many hopes upon the process.' This expression, and his writings abound

in such, illustrates what has been already said regarding his experiments being suggested and guided by his

theoretic conceptions. His mind was full of hopes and hypotheses, but he always brought them to an

experimental test. The record of his planned and executed experiments would, I doubt not, show a high ratio

of hopes disappointed to hopes fulfilled; but every case of fulfilment abolished all memory of defeat;

After the description of the general character of this new force, Faraday states with the emphasis here

reproduced its mode of action: 'The law of action appears to be that the line or axis of

MAGNECRYSTALLIC force (being the resultant of the action of all the molecules) tends to place itself

parallel, or as a tangent, to the magnetic curve, or line of magnetic force, passing through the place where the

crystal is situated.' The magnecrystallic force, moreover, appears to him 'to be clearly distinguished from the

magnetic or diamagnetic forces, in that it causes neither approach nor recession, consisting not in attraction or

repulsion, but in giving a certain determinate position to the mass under its influence.' And then he goes on

'very carefully to examine and prove the conclusion that there was no connection of the force with attractive

or repulsive influences.' With the most refined ingenuity he shows that, under certain circumstances, the

magnecrystallic force can cause the centre of gravity of a highly magnetic body to retreat from the poles,

and the centre of gravity of a highly diamagnetic body to approach them. His experiments root his mind more

and more firmly in the conclusion that 'neither attraction nor repulsion causes the set, or governs the final

position' of the crystal in the magnetic field. That the force which does so is therefore 'distinct in its character

and effects from the magnetic and diamagnetic forms of force. On the other hand,' he continues, 'it has a most

manifest relation to the crystalline structure of bismuth and other bodies, and therefore to the power by which

And here follows one of those expressions which characterize the conceptions of Faraday in regard to force

generally:'It appears to me impossible to conceive of the results in any other way than by a mutual reaction

of the magnetic force, and the force of the particles of the crystals upon each other.' He proves that the action

of the force, though thus molecular, is an action at a distance; he shows that a bismuth crystal can cause a

freely suspended magnetic needle to set parallel to its magnecrystallic axis. Few living men are aware of the

difficulty of obtaining results like this, or of the delicacy necessary to their attainment. 'But though it thus

takes up the character of a force acting at a distance, still it is due to that power of the particles which makes

them cohere in regular order and gives the mass its crystalline aggregation, which we call at other times the

attraction of aggregation, and so often speak of as acting at insensible distances.' Thus he broods over this

new force, and looks at it from all possible points of inspection. Experiment follows experiment, as thought

follows thought. He will not relinquish the subject as long as a hope exists of throwing more light upon it. He

knows full well the anomalous nature of the conclusion to which his experiments lead him. But experiment to

him is final, and he will not shrink from the conclusion. 'This force,' he says, 'appears to me to be very strange

and striking in its character. It is not polar, for there is no attraction or repulsion.' And then, as if startled by

his own utterance, he asks'What is the nature of the mechanical force which turns the crystal round, and

makes it affect a magnet?'... 'I do not remember,' he continues 'heretofore such a case of force as the present

one, where a body is brought into position only, without attraction or repulsion.'

Plucker, the celebrated geometer already mentioned, who pursued experimental physics for many years of his

life with singular devotion and success, visited Faraday in those days, and repeated before him his beautiful

experiments on magnetooptic action. Faraday repeated and verified Plucker's observations, and concluded,

what he at first seemed to doubt, that Plucker's results and magnecrystallic action had the same origin.

At the end of his papers, when he takes a last look along the line of research, and then turns his eyes to the

future, utterances quite as much emotional as scientific escape from Faraday. 'I cannot,' he says, at the end of

his first paper on magnecrystallic action, 'conclude this series of researches without remarking how rapidly

the knowledge of molecular forces grows upon us, and how strikingly every investigation tends to develop

more and more their importance, and their extreme attraction as an object of study. A few years ago

magnetism was to us an occult power, affecting only a few bodies, now it is found to influence all bodies, and

to possess the most intimate relations with electricity, heat, chemical action, light, crystallization, and through

it, with the forces concerned in cohesion; and we may, in the present state of things, well feel urged to

continue in our labours, encouraged by the hope of bringing it into a bond of union with gravity itself.'

A brief space will, perhaps, be granted me here to state the further progress of an investigation which

interested Faraday so much. Drawn by the fame of Bunsen as a teacher, in the year 1848 I became a student

in the University of Marburg, in Hesse Cassel. Bunsen's behaviour to me was that of a brother as well as that

of a teacher, and it was also my happiness to make the acquaintance and gain the friendship of Professor

Knoblauch, so highly distinguished by his researches on Radiant Heat. Plucker's and Faraday's investigations

filled all minds at the time, and towards the end of 1849, Professor Knoblauch and myself commenced a joint

investigation of the entire question. Long discipline was necessary to give us due mastery over it. Employing

a method proposed by Dove, we examined the optical properties of our crystals ourselves; and these optical

observations went hand in hand with our magnetic experiments. The number of these experiments was very

great, but for a considerable time no fact of importance was added to those already published. At length,

however, it was our fortune to meet with various crystals whose deportment could not be brought under the

laws of magnecrystallic action enunciated by Plucker. We also discovered instances which led us to suppose

that the magnecrystallic force was by no means independent, as alleged, of the magnetism or diamagnetism

of the mass of the crystal. Indeed, the more we worked at the subject, the more clearly did it appear to us that

the deportment of crystals in the magnetic field was due, not to a force previously unknown, but to the

modification of the known forces of magnetism and diamagnetism by crystalline aggregation.

An eminent example of magnecrystallic action adduced by Plucker, and experimented on by Faraday, was

Iceland spar. It is what in optics is called a negative crystal, and according to the law of Plucker, the axis of

such a crystal was always repelled by a magnet. But we showed that it was only necessary to substitute, in

whole or in part, carbonate of iron for carbonate of lime, thus changing the magnetic but not the optical

character of the crystal, to cause the axis to be attracted. That the deportment of magnetic crystals is exactly

antithetical to that of diamagnetic crystals isomorphous with the magnetic ones, was proved to be a general

law of action. In all cases, the line which in a diamagnetic crystal set equatorially, always set itself in an

isomorphous magnetic crystal axially. By mechanical compression other bodies were also made to imitate the

These and numerous other results bearing upon the question were published at the time in the 'Philosophical

Magazine' and in 'Poggendorff's Annalen'; and the investigation of diamagnetism and magnecrystallic action

was subsequently continued by me in the laboratory of Professor Magnus of Berlin. In December, 1851, after

I had quitted Germany, Dr. Bence Jones went to the Prussian capital to see the celebrated experiments of Du

Bois Reymond. Influenced, I suppose, by what he there heard, he afterwards invited me to give a Friday

evening discourse at the Royal Institution. I consented, not without fear and trembling. For the Royal

Institution was to me a kind of dragon's den, where tact and strength would be necessary to save me from

destruction. On February 11, 1853, the discourse was given, and it ended happily. I allude to these things, that

I may mention that, though my aim and object in that lecture was to subvert the notions both of Faraday and

Plucker, and to establish in opposition to their views what I regarded as the truth, it was very far from

producing in Faraday either enmity or anger. At the conclusion of the lecture, he quitted his accustomed seat,

crossed the theatre to the corner into which I had shrunk, shook me by the hand, and brought me back to the

table. Once more, subsequently, and in connection with a related question, I ventured to differ from him still

more emphatically. It was done out of trust in the greatness of his character; nor was the trust misplaced. He

felt my public dissent from him; and it pained me afterwards to the quick to think that I had given him even

momentary annoyance. It was, however, only momentary. His soul was above all littleness and proof to all

egotism. He was the same to me afterwards that he had been before; the very chance expression which led me

It required long subsequent effort to subdue the complications of magnecrystallic action, and to bring under

the dominion of elementary principles the vast mass of facts which the experiments of Faraday and Plucker

had brought to light. It was proved by Reich, Edmond Becquerel, and myself, that the condition of

diamagnetic bodies, in virtue of which they were repelled by the poles of a magnet, was excited in them by

those poles; that the strength of this condition rose and fell with, and was proportional to, the strength of the

acting magnet. It was not then any property possessed permanently by the bismuth, and which merely

required the development of magnetism to act upon it, that caused the repulsion; for then the repulsion would

have been simply proportional to the strength of the influencing magnet, whereas experiment proved it to

augment as the square of the strength. The capacity to be repelled was therefore not inherent in the bismuth,

but induced. So far an identity of action was established between magnetic and diamagnetic bodies. After this

the deportment of magnetic bodies, 'normal' and 'abnormal'; crystalline, amorphous, and compressed, was

compared with that of crystalline, amorphous, and compressed diamagnetic bodies; and by a series of

experiments, executed in the laboratory of this Institution, the most complete antithesis was established

between magnetism and diamagnetism. This antithesis embraced the quality of polarity,the theory of

reversed polarity, first propounded by Faraday, being proved to be true. The discussion of the question was

very brisk. On the Continent Professor Wilhelm Weber was the ablest and most successful supporter of the

doctrine of diamagnetic polarity; and it was with an apparatus, devised by him and constructed under his own

superintendence, by Leyser of Leipzig, that the last demands of the opponents of diamagnetic polarity were

satisfied. The establishment of this point was absolutely necessary to the explanation of magnecrystallic

With that admirable instinct which always guided him, Faraday had seen that it was possible, if not probable,

that the diamagnetic force acts with different degrees of intensity in different directions, through the mass of

a crystal. In his studies on electricity, he had sought an experimental reply to the question whether crystalline

bodies had not different specific inductive capacities in different directions, but he failed to establish any

difference of the kind. His first attempt to establish differences of diamagnetic action in different directions

through bismuth, was also a failure; but he must have felt this to be a point of cardinal importance, for he

returned to the subject in 1850, and proved that bismuth was repelled with different degrees of force in

different directions. It seemed as if the crystal were compounded of two diamagnetic bodies of different

strengths, the substance being more strongly repelled across the magnecrystallic axis than along it. The

same result was obtained independently, and extended to various other bodies, magnetic as well as

diamagnetic, and also to compressed substances, a little subsequently by myself.

The law of action in relation to this point is, that in diamagnetic crystals, the line along which the repulsion is

a maximum, sets equatorially in the magnetic field; while in magnetic crystals the line along which the

attraction is a maximum sets from pole to pole. Faraday had said that the magnecrystallic force was neither

attraction nor repulsion. Thus far he was right. It was neither taken singly, but it was both. By the

combination of the doctrine of diamagnetic polarity with these differential attractions and repulsions, and by

paying due regard to the character of the magnetic field, every fact brought to light in the domain of

magnecrystallic action received complete explanation. The most perplexing of those facts were shown to

result from the action of mechanical couples, which the proved polarity both of magnetism and diamagnetism

brought into play. Indeed the thoroughness with which the experiments of Faraday were thus explained, is the

most striking possible demonstration of the marvellous precision with which they were executed.

When an experimental result was obtained by Faraday it was instantly enlarged by his imagination. I am

acquainted with no mind whose power and suddenness of expansion at the touch of new physical truth could

be ranked with his. Sometimes I have compared the action of his experiments on his mind to that of highly

combustible matter thrown into a furnace; every fresh entry of fact was accompanied by the immediate

development of light and heat. The light, which was intellectual, enabled him to see far beyond the

boundaries of the fact itself, and the heat, which was emotional, urged him to the conquest of this

newlyrevealed domain. But though the force of his imagination was enormous, he bridled it like a mighty

In virtue of the expansive power which his vivid imagination conferred upon him, he rose from the smallest

beginnings to the grandest ends. Having heard from Zantedeschi that Bancalari had established the

magnetism of flame, he repeated the experiments and augmented the results. He passed from flames to gases,

examining and revealing their magnetic and diamagnetic powers; and then he suddenly rose from his bubbles

of oxygen and nitrogen to the atmospheric envelope of the earth itself, and its relations to the great question

of terrestrial magnetism. The rapidity with which these everaugmenting thoughts assumed the form of

experiments is unparalleled. His power in this respect is often best illustrated by his minor investigations,

and, perhaps, by none more strikingly than by his paper 'On the Diamagnetic Condition of Flame and Gases,'

published as a letter to Mr. Richard Taylor, in the 'Philosophical Magazine' for December, 1847. After

verifying, varying, and expanding the results of Bancalari, he submitted to examination heated aircurrents,

produced by platinum spirals placed in the magnetic field, and raised to incandescence by electricity. He then

examined the magnetic deportment of gases generally. Almost all of these gases are invisible; but he must,

nevertheless, track them in their unseen courses. He could not effect this by mingling smoke with his gases,

for the action of his magnet upon the smoke would have troubled his conclusions. He, therefore, 'caught' his

gases in tubes, carried them out of the magnetic field, and made them reveal themselves at a distance from the

Immersing one gas in another, he determined their differential action; results of the utmost beauty being thus

arrived at. Perhaps the most important are those obtained with atmospheric air and its two constituents.

Oxygen, in various media, was strongly attracted by the magnet; in coalgas, for example, it was powerfully

magnetic, whereas nitrogen was diamagnetic. Some of the effects obtained with oxygen in coalgas were

strikingly beautiful. When the fumes of chloride of ammonium (a diamagnetic substance) were mingled with

the oxygen, the cloud of chloride behaved in a most singular manner, 'The attraction of iron filings,' says

Faraday, 'to a magnetic pole is not more striking than the appearance presented by the oxygen under these

On observing this deportment the question immediately occurs to him, Can we not separate the oxygen of

the atmosphere from its nitrogen by magnetic analysis? It is the perpetual occurrence of such questions that

marks the great experimenter. The attempt to analyze atmospheric air by magnetic force proved a failure, like

the previous attempt to influence crystallization by the magnet. The enormous comparative power of the

force of crystallization I have already assigned as a reason for the incompetence of the magnet to determine

molecular arrangement; in the present instance the magnetic analysis is opposed by the force of diffusion,

which is also very strong comparatively. The same remark applies to, and is illustrated by, another

experiment subsequently executed by Faraday. Water is diamagnetic, sulphate of iron is strongly magnetic.

He enclosed 'a dilute solution of sulphate of iron in a tube, and placed the lower end of the tube between the

poles of a powerful horseshoe magnet for days together,' but he could produce 'no concentration of the

solution in the part near the magnet.' Here also the diffusibility of the salt was too powerful for the force

The experiment last referred to is recorded in a paper presented to the Royal Society on the 2nd August,

1850, in which he pursues the investigation of the magnetism of gases. Newton's observations on

soapbubbles were often referred to by Faraday. His delight in a soapbubble was like that of a boy, and he

often introduced them into his lectures, causing them, when filled with air, to float on invisible seas of

carbonic acid, and otherwise employing them as a means of illustration. He now finds them exceedingly

useful in his experiments on the magnetic condition of gases. A bubble of air in a magnetic field occupied by

air was unaffected, save through the feeble repulsion of its envelope. A bubble of nitrogen, on the contrary,

was repelled from the magnetic axis with a force far surpassing that of a bubble of air. The deportment of

oxygen in air 'was very impressive, the bubble being pulled inward or towards the axial line, sharply and

He next labours to establish the true magnetic zero, a problem not so easy as might at first sight be imagined.

For the action of the magnet upon any gas, while surrounded by air or any other gas, can only be differential;

and if the experiment were made in vacuo, the action of the envelope, in this case necessarily of a certain

thickness, would trouble the result. While dealing with this subject, Faraday makes some noteworthy

observations regarding space. In reference to the Torricellian vacuum, he says, 'Perhaps it is hardly necessary

for me to state that I find both iron and bismuth in such vacua perfectly obedient to the magnet. From such

experiments, and also from general observations and knowledge, it seems manifest that the lines of magnetic

force can traverse pure space, just as gravitating force does, and as statical electrical forces do, and therefore

space has a magnetic relation of its own, and one that we shall probably find hereafter to be of the utmost

importance in natural phenomena. But this character of space is not of the same kind as that which, in relation

to matter, we endeavour to express by the terms magnetic and diamagnetic. To confuse these together would

be to confound space with matter, and to trouble all the conceptions by which we endeavour to understand

and work out a progressively clearer view of the mode of action, and the laws of natural forces. It would be as

if in gravitation or electric forces, one were to confound the particles acting on each other with the space

across which they are acting, and would, I think, shut the door to advancement. Mere space cannot act as

matter acts, even though the utmost latitude be allowed to the hypothesis of an ether; and admitting that

hypothesis, it would be a large additional assumption to suppose that the lines of magnetic force are

vibrations carried on by it, whilst as yet we have no proof that time is required for their propagation, or in

what respect they may, in general character, assimilate to or differ from their respective lines of gravitating,

Pure space he assumes to be the true magnetic zero, but he pushes his inquiries to ascertain whether among

material substances there may not be some which resemble space. If you follow his experiments, you will

soon emerge into the light of his results. A torsionbeam was suspended by a skein of cocoon silk; at one end

of the beam was fixed a crosspiece 1 1/2 inch long. Tubes of exceedingly thin glass, filled with various

gases, and hermetically sealed, were suspended in pairs from the two ends of the crosspiece. The position of

the rotating torsionhead was such that the two tubes were at opposite sides of, and equidistant from, the

magnetic axis, that is to say from the line joining the two closely approximated polar points of an

electromagnet. His object was to compare the magnetic action of the gases in the two tubes. When one tube

was filled with oxygen, and the other with nitrogen, on the supervention of the magnetic force, the oxygen

was pulled towards the axis, the nitrogen being pushed out. By turning the torsionhead they could be

restored to their primitive position of equidistance, where it is evident the action of the glass envelopes was

annulled. The amount of torsion necessary to reestablish equidistance expressed the magnetic difference of

And then he compared oxygen with oxygen at different pressures. One of his tubes contained the gas at the

pressure of 30 inches of mercury, another at a pressure of 15 inches of mercury, a third at a pressure of 10

inches, while a fourth was exhausted as far as a good airpump renders exhaustion possible. 'When the first

of these was compared with the other three, the effect was most striking.' It was drawn towards the axis when

the magnet was excited, the tube containing the rarer gas being apparently driven away, and the greater the

difference between the densities of the two gases, the greater was the energy of this action.

And now observe his mode of reaching a material magnetic zero. When a bubble of nitrogen was exposed in

air in the magnetic field, on the supervention of the power, the bubble retreated from the magnet. A less acute

observer would have set nitrogen down as diamagnetic; but Faraday knew that retreat, in a medium composed

in part of oxygen, might be due to the attraction of the latter gas, instead of to the repulsion of the gas

immersed in it. But if nitrogen be really diamagnetic, then a bubble or bulb filled with the dense gas will

overcome one filled with the rarer gas. From the crosspiece of his torsionbalance he suspended his bulbs of

nitrogen, at equal distances from the magnetic axis, and found that the rarefaction, or the condensation of the

gas in either of the bulbs had not the slightest influence. When the magnetic force was developed, the bulbs

remained in their first position, even when one was filled with nitrogen, and the other as far as possible

exhausted. Nitrogen, in fact, acted 'like space itself'; it was neither magnetic nor diamagnetic.

He cannot conveniently compare the paramagnetic force of oxygen with iron, in consequence of the

exceeding magnetic intensity of the latter substance; but he does compare it with the sulphate of iron, and

finds that, bulk for bulk, oxygen is equally magnetic with a solution of this substance in water 'containing

seventeen times the weight of the oxygen in crystallized protosulphate of iron, or 3.4 times its weight of

metallic iron in that state of combination.' By its capability to deflect a fine glass fibre, he finds that the

attraction of this bulb of oxygen, containing only 0.117 of a grain of the gas, at an average distance of more

than an inch from the magnetic axis, is about equal to the gravitating force of the same amount of oxygen as

These facts could not rest for an instant in the mind of Faraday without receiving that expansion to which I

have already referred. 'It is hardly necessary,' he writes, 'for me to say here that this oxygen cannot exist in

the atmosphere exerting such a remarkable and high amount of magnetic force, without having a most

important influence on the disposition of the magnetism of the earth, as a planet; especially if it be

remembered that its magnetic condition is greatly altered by variations of its density and by variations of its

temperature. I think I see here the real cause of many of the variations of that force, which have been, and are

now so carefully watched on different parts of the surface of the globe. The daily variation, and the annual

variation, both seem likely to come under it; also very many of the irregular continual variations, which the

photographic process of record renders so beautifully manifest. If such expectations be confirmed, and the

influence of the atmosphere be found able to produce results like these, then we shall probably find a new

relation between the aurora borealis and the magnetism of the earth, namely, a relation established, more or

less, through the air itself in connection with the space above it; and even magnetic relations and variations,

which are not as yet suspected, may be suggested and rendered manifest and measurable, in the further

development of what I will venture to call Atmospheric Magnetism. I may be oversanguine in these

expectations, but as yet I am sustained in them by the apparent reality, simplicity, and sufficiency of the cause

assumed, as it at present appears to my mind. As soon as I have submitted these views to a close

consideration, and the test of accordance with observation, and, where applicable, with experiments also, I

Two elaborate memoirs are then devoted to the subject of Atmospheric Magnetism; the first sent to the Royal

Society on the 9th of October, and the second on the 19th of November, 1850. In these memoirs he discusses

the effects of heat and cold upon the magnetism of the air, and the action on the magnetic needle, which must

result from thermal changes. By the convergence and divergence of the lines of terrestrial magnetic force, he

shows how the distribution of magnetism, in the earth's atmosphere, is effected. He applies his results to the

explanation of the Annual and of the Diurnal Variation: he also considers irregular variations, including the

action of magnetic storms. He discusses, at length, the observations at St. Petersburg, Greenwich, Hobarton,

St. Helena, Toronto, and the Cape of Good Hope; believing that the facts, revealed by his experiments,

In the year 1851, I had the honour of an interview with Humboldt, in Berlin, and his parting words to me then

were, 'Tell Faraday that I entirely agree with him, and that he has, in my opinion, completely explained the

variation of the declination.' Eminent men have since informed me that Humboldt was hasty in expressing

this opinion. In fact, Faraday's memoirs on atmospheric magnetism lost much of their forceperhaps too

muchthrough the important discovery of the relation of the variation of the declination to the number of

the solar spots. But I agree with him and M. Edmond Becquerel, who worked independently at this subject, in

thinking, that a body so magnetic as oxygen, swathing the earth, and subject to variations of temperature,

diurnal and annual, must affect the manifestations of terrestrial magnetism.[1] The air that stands upon a

single square foot of the earth's surface is, according to Faraday, equivalent in magnetic force to 8160 lbs. of

crystallized protosulphate of iron. Such a substance cannot be absolutely neutral as regards the deportment of

the magnetic needle. But Faraday's writings on this subject are so voluminous, and the theoretic points are so

novel and intricate, that I shall postpone the complete analysis of these researches to a time when I can lay

[1] This persuasion has been greatly strengthened by the recent perusal of a paper by Mr. Baxendell.

The scientific picture of Faraday would not be complete without a reference to his speculative writings. On

Friday, January 19, 1844, he opened the weekly eveningmeetings of the Royal Institution by a discourse

entitled 'A speculation touching Electric Conduction and the nature of Matter.' In this discourse he not only

attempts the overthrow of Dalton's Theory of Atoms, but also the subversion of all ordinary scientific ideas

regarding the nature and relations of Matter and Force. He objected to the use of the term atom:'I have not

yet found a mind,' he says, 'that did habitually separate it from its accompanying temptations; and there can

be no doubt that the words definite proportions, equivalent, primes, which did and do fully express all the

facts of what is usually called the atomic theory in chemistry, were dismissed because they were not

expressive enough, and did not say all that was in the mind of him who used the word atom in their stead.'

A moment will be granted me to indicate my own view of Faraday's position here. The word 'atom' was not

used in the stead of definite proportions, equivalents, or primes. These terms represented facts that followed

from, but were not equivalent to, the atomic theory. Facts cannot satisfy the mind: and the law of definite

combining proportions being once established, the question 'why should combination take place according to

that law?' is inevitable. Dalton answered this question by the enunciation of the Atomic Theory, the

fundamental idea of which is, in my opinion, perfectly secure. The objection of Faraday to Dalton might be

urged with the same substantial force against Newton: it might be stated with regard to the planetary motions

that the laws of Kepler revealed the facts; that the introduction of the principle of gravitation was an addition

to the facts. But this is the essence of all theory. The theory is the backward guess from fact to principle; the

conjecture, or divination regarding something, which lies behind the facts, and from which they flow in

necessary sequence. If Dalton's theory, then, account for the definite proportions observed in the

combinations of chemistry, its justification rests upon the same basis as that of the principle of gravitation.

All that can in strictness be said in either case is that the facts occur as if the principle existed.

The manner in which Faraday himself habitually deals with his hypotheses is revealed in this lecture. He

incessantly employed them to gain experimental ends, but he incessantly took them down, as an architect

removes the scaffolding when the edifice is complete. 'I cannot but doubt,' he says, 'that he who as a mere

philosopher has most power of penetrating the secrets of nature, and guessing by hypothesis at her mode of

working, will also be most careful for his own safe progress and that of others, to distinguish the knowledge

which consists of assumption, by which I mean theory and hypothesis, from that which is the knowledge of

facts and laws.' Faraday himself, in fact, was always 'guessing by hypothesis,' and making theoretic

I have already more than once dwelt on the vividness with which he realised molecular conditions; we have a

fine example of this strength and brightness of imagination in the present 'speculation.' He grapples with the

notion that matter is made up of particles, not in absolute contact, but surrounded by interatomic space.

'Space,' he observes, 'must be taken as the only continuous part of a body so constituted. Space will permeate

all masses of matter in every direction like a net, except that in place of meshes it will form cells, isolating

Let us follow out this notion; consider, he argues, the case of a nonconductor of electricity, such for

example as shelllac, with its molecules, and intermolecular spaces running through the mass. In its case

space must be an insulator; for if it were a conductor it would resemble 'a fine metallic web,' penetrating the

lac in every direction. But the fact is that it resembles the wax of black sealingwax, which surrounds and

insulates the particles of conducting carbon, interspersed throughout its mass. In the case of shelllac,

But now, take the case of a conducting metal. Here we have, as before, the swathing of space round every

atom. If space be an insulator there can be no transmission of electricity from atom to atom. But there is

transmission; hence space is a conductor. Thus he endeavours to hamper the atomic theory. 'The reasoning,'

he says, 'ends in a subversion of that theory altogether; for if space be an insulator it cannot exist in

conducting bodies, and if it be a conductor it cannot exist in insulating bodies. Any ground of reasoning,' he

adds, as if carried away by the ardour of argument, 'which tends to such conclusions as these must in itself be

He then tosses the atomic theory from horn to horn of his dilemmas. What do we know, he asks, of the atom

apart from its force? You imagine a nucleus which may be called a, and surround it by forces which may be

called m; 'to my mind the a or nucleus vanishes, and the substance consists in the powers of m. And indeed

what notion can we form of the nucleus independent of its powers? What thought remains on which to hang

the imagination of an a independent of the acknowledged forces?' Like Boscovich, he abolishes the atom, and

With his usual courage and sincerity he pushes his view to its utmost consequences. 'This view of the

constitution of matter,' he continues, 'would seem to involve necessarily the conclusion that matter fills all

space, or at least all space to which gravitation extends; for gravitation is a property of matter dependent on a

certain force, and it is this force which constitutes the matter. In that view matter is not merely mutually

penetrable;[1] but each atom extends, so to say, throughout the whole of the solar system, yet always

It is the operation of a mind filled with thoughts of this profound, strange, and subtle character that we have

to take into account in dealing with Faraday's later researches. A similar cast of thought pervades a letter

addressed by Faraday to Mr. Richard Phillips, and published in the 'Philosophical Magazine' for May, 1846.

It is entitled 'Thoughts on Rayvibrations,' and it contains one of the most singular speculations that ever

emanated from a scientific mind. It must be remembered here, that though Faraday lived amid such

speculations he did not rate them highly, and that he was prepared at any moment to change them or let them

go. They spurred him on, but they did not hamper him. His theoretic notions were fluent; and when minds

less plastic than his own attempted to render those fluxional images rigid, he rebelled. He warns Phillips

moreover, that from first to last, 'he merely threw out as matter for speculation the vague impressions of his

mind; for he gave nothing as the result of sufficient consideration, or as the settled conviction, or even

The gist of this communication is that gravitating force acts in lines across space, and that the vibrations of

light and radiant heat consist in the tremors of these lines of force. 'This notion,' he says, 'as far as it is

admitted, will dispense with the ether, which, in another view is supposed to be the medium in which these

vibrations take place.' And he adds further on, that his view 'endeavours to dismiss the ether but not the

vibrations.' The idea here set forth is the natural supplement of his previous notion, that it is gravitating force

which constitutes matter, each atom extending, so to say, throughout the whole of the solar system.

'I think it likely that I have made many mistakes in the preceding pages, for even to myself my ideas on this

point appear only as the shadow of a speculation, or as one of those impressions upon the mind which are

allowable for a time as guides to thought and research. He who labours in experimental inquiries, knows how

numerous these are, and how often their apparent fitness and beauty vanish before the progress and

Let it then be remembered that Faraday entertained notions regarding matter and force altogether distinct

from the views generally held by scientific men. Force seemed to him an entity dwelling along the line in

which it is exerted. The lines along which gravity acts between the sun and earth seem figured in his mind as

so many elastic strings; indeed he accepts the assumed instantaneity of gravity as the expression of the

enormous elasticity of the 'lines of weight.' Such views, fruitful in the case of magnetism, barren, as yet, in

the case of gravity, explain his efforts to transform this latter force. When he goes into the open air and

permits his helices to fall, to his mind's eye they are tearing through the lines of gravitating power, and hence

his hope and conviction that an effect would and ought to be produced. It must ever be borne in mind that

Faraday's difficulty in dealing with these conceptions was at bottom the same as that of Newton; that he is in

fact trying to overleap this difficulty, and with it probably the limits prescribed to the intellect itself.

The idea of lines of magnetic force was suggested to Faraday by the linear arrangement of iron filings when

scattered over a magnet. He speaks of and illustrates by sketches, the deflection, both convergent and

divergent, of the lines of force, when they pass respectively through magnetic and diamagnetic bodies. These

notions of concentration and divergence are also based on the direct observation of his filings. So long did he

brood upon these lines; so habitually did he associate them with his experiments on induced currents, that the

association became 'indissoluble,' and he could not think without them. 'I have been so accustomed,' he

writes, 'to employ them, and especially in my last researches, that I may have unwittingly become prejudiced

in their favour, and ceased to be a clearsighted judge. Still, I have always endeavoured to make experiment

the test and controller of theory and opinion; but neither by that nor by close crossexamination in principle,

In his later researches on magnecrystallic action, the idea of lines of force is extensively employed; it indeed

led him to an experiment which lies at the root of the whole question. In his subsequent researches on

Atmospheric Magnetism the idea receives still wider application, showing itself to be wonderfully flexible

and convenient. Indeed without this conception the attempt to seize upon the magnetic actions, possible or

actual, of the atmosphere would be difficult in the extreme; but the notion of lines of force, and of their

divergence and convergence, guides Faraday without perplexity through all the intricacies of the question.

After the completion of those researches, and in a paper forwarded to the Royal Society on October 22, 1851,

he devotes himself to the formal development and illustration of his favourite idea. The paper bears the title,

'On lines of magnetic force, their definite character, and their distribution within a magnet and through space.'

A deep reflectiveness is the characteristic of this memoir. In his experiments, which are perfectly beautiful

and profoundly suggestive, he takes but a secondary delight. His object is to illustrate the utility of his

conception of lines of force. 'The study of these lines,' he says, 'has at different times been greatly influential

in leading me to various results which I think prove their utility as well as fertility.'

Faraday for a long period used the lines of force merely as 'a representative idea.' He seemed for a time

averse to going further in expression than the lines themselves, however much further he may have gone in

idea. That he believed them to exist at all times round a magnet, and irrespective of the existence of magnetic

matter, such as iron filings, external to the magnet, is certain. No doubt the space round every magnet

presented itself to his imagination as traversed by loops of magnetic power; but he was chary in speaking of

the physical substratum of those loops. Indeed it may be doubted whether the physical theory of lines of force

presented itself with any distinctness to his own mind. The possible complicity of the luminiferous ether in

magnetic phenomena was certainly in his thoughts. 'How the magnetic force,' he writes, 'is transferred

through bodies or through space we know not; whether the result is merely action at a distance, as in the case

of gravity; or by some intermediate agency, as in the case of light, heat, the electric current, and (as I believe)

static electric action. The idea of magnetic fluids, as applied by some, or of Magnetic centres of action, does

not include that of the latter kind of transmission, but the idea of lines of force does.' And he continues

thus: 'I am more inclined to the notion that in the transmission of the [magnetic] force there is such an

action [an intermediate agency] external to the magnet, than that the effects are merely attraction and

repulsion at a distance. Such an affection may be a function of the ether; for it is not at all unlikely that, if

there be an ether, it should have other uses than simply the conveyance of radiations.' When he speaks of the

magnet in certain cases, 'revolving amongst its own forces,' he appears to have some conception of this kind

A great part of the investigation completed in October, 1851, was taken up with the motions of wires round

the poles of a magnet and the converse. He carried an insulated wire along the axis of a bar magnet from its

pole to its equator, where it issued from the magnet, and was bent up so as to connect its two ends. A

complete circuit, no part of which was in contact with the magnet, was thus obtained. He found that when the

magnet and the external wire were rotated together no current was produced; whereas, when either of them

was rotated and the other left at rest currents were evolved. He then abandoned the axial wire, and allowed

the magnet itself to take its place; the result was the same.[2] It was the relative motion of the magnet and the

The lines of force have their roots in the magnet, and though they may expand into infinite space, they

eventually return to the magnet. Now these lines may be intersected close to the magnet or at a distance from

it. Faraday finds distance to be perfectly immaterial so long as the number of lines intersected is the same.

For example, when the loop connecting the equator and the pole of his barmagnet performs one complete

revolution round the magnet, it is manifest that all the lines of force issuing from the magnet are once

intersected. Now it matters not whether the loop be ten feet or ten inches in length, it matters not how it may

be twisted and contorted, it matters not how near to the magnet or how distant from it the loop may be, one

revolution always produces the same amount of current electricity, because in all these cases all the lines of

From the external portion of the circuit he passes in idea to the internal, and follows the lines of force into the

body of the magnet itself. His conclusion is that there exist lines of force within the magnet of the same

nature as those without. What is more, they are exactly equal in amount to those without. They have a

relation in direction to those without; and in fact are continuations of them.... 'Every line of force, therefore,

at whatever distance it may be taken from the magnet, must be considered as a closed circuit, passing in some

part of its course through the magnet, and having an equal amount of force in every part of its course.'

All the results here described were obtained with moving metals. 'But,' he continues with profound sagacity,

'mere motion would not generate a relation, which had not a foundation in the existence of some previous

state; and therefore the quiescent metals must be in some relation to the active centre of force,' that is to the

magnet. He here touches the core of the whole question, and when we can state the condition into which the

conducting wire is thrown before it is moved, we shall then be in a position to understand the physical

In this inquiry Faraday worked with steel magnets, the force of which varies with the distance from the

magnet. He then sought a uniform field of magnetic force, and found it in space as affected by the magnetism

of the earth. His next memoir, sent to the Royal Society, December 31, 1851, is 'on the employment of the

Induced Magnetoelectro Current as a test and measure of magnetic forces.' He forms rectangles and rings,

and by ingenious and simple devices collects the opposed currents which are developed in them by rotation

across the terrestrial lines of magnetic force. He varies the shapes of his rectangles while preserving their

areas constant, and finds that the constant area produces always the same amount of current per revolution.

The current depends solely on the number of lines of force intersected, and when this number is kept constant

the current remains constant too. Thus the lines of magnetic force are continually before his eyes, by their aid

he colligates his facts, and through the inspirations derived from them he vastly expands the boundaries of

our experimental knowledge. The beauty and exactitude of the results of this investigation are extraordinary. I

cannot help thinking while I dwell upon them, that this discovery of magnetoelectricity is the greatest

experimental result ever obtained by an investigator. It is the Mont Blanc of Faraday's own achievements. He

always worked at great elevations, but a higher than this he never subsequently attained.

[1] He compares the interpenetration of two atoms to the coalescence of two distinct waves, which though for

a moment blended to a single mass, preserve their individuality, and afterwards separate.

[2] In this form the experiment is identical with one made twenty years earlier. See page 34.

The terms unity and convertibility, as applied to natural forces, are often employed in these investigations,

many profound and beautiful thoughts respecting these subjects being expressed in Faraday's memoirs.

Modern inquiry has, however, much augmented our knowledge of the relationship of natural forces, and it

seems worth while to say a few words here, tending to clear up certain misconceptions which appear to exist

The whole stock of energy or workingpower in the world consists of attractions, repulsions, and motions. If

the attractions and repulsions are so circumstanced as to be able to produce motion, they are sources of

workingpower, but not otherwise. Let us for the sake of simplicity confine our attention to the case of

attraction. The attraction exerted between the earth and a body at a distance from the earth's surface is a

source of workingpower; because the body can be moved by the attraction, and in falling to the earth can

perform work. When it rests upon the earth's surface it is not a source of power or energy, because it can fall

no further. But though it has ceased to be a source of energy, the attraction of gravity still acts as a force,

The same remarks apply to attracting atoms and molecules. As long as distance separates them, they can

move across it in obedience to the attraction, and the motion thus produced may, by proper appliances, be

caused to perform mechanical work. When, for example, two atoms of hydrogen unite with one of oxygen, to

form water the atoms are first drawn towards each otherthey move, they clash, and then by virtue of their

resiliency, they recoil and quiver. To this quivering motion we give the name of heat. Now this quivering

motion is merely the redistribution of the motion produced by the chemical affinity; and this is the only sense

in which chemical affinity can be said to be converted into heat. We must not imagine the chemical attraction

destroyed, or converted into anything else. For the atoms, when mutually clasped to form a molecule of

water, are held together by the very attraction which first drew them towards each other. That which has

really been expended is the pull exerted through the space by which the distance between the atoms has been

If this be understood, it will be at once seen that gravity may in this sense be said to be convertible into heat;

that it is in reality no more an outstanding and inconvertible agent, as it is sometimes stated to be, than

chemical affinity. By the exertion of a certain pull, through a certain space, a body is caused to clash with a

certain definite velocity against the earth. Heat is thereby developed, and this is the only sense in which

gravity can be said to be converted into heat. In no case is the force which produces the motion annihilated or

changed into anything else. The mutual attraction of the earth and weight exists when they are in contact as

when they were separate; but the ability of that attraction to employ itself in the production of motion does

The transformation, in this case, is easily followed by the mind's eye. First, the weight as a whole is set in

motion by the attraction of gravity. This motion of the mass is arrested by collision with the earth; being

And when we reverse the process, and employ those tremors of heat to raise a weight, as is done through the

intermediation of an elastic fluid in the steamengine, a certain definite portion of the molecular motion is

destroyed in raising the weight. In this sense, and this sense only, can the heat be said to be converted into

gravity, or more correctly, into potential energy of gravity. It is not that the destruction of the heat has created

any new attraction, but simply that the old attraction has now a power conferred upon it, of exerting a certain

definite pull in the interval between the startingpoint of the falling weight and its collision with the earth.

So also as regards magnetic attraction: when a sphere of iron placed at some distance from a magnet rushes

towards the magnet, and has its motion stopped by collision, an effect mechanically the same as that

produced by the attraction of gravity occurs. The magnetic attraction generates the motion of the mass, and

the stoppage of that motion produces heat. In this sense, and in this sense only, is there a transformation of

magnetic work into heat. And if by the mechanical action of heat, brought to bear by means of a suitable

machine, the sphere be torn from the magnet and again placed at a distance, a power of exerting a pull

through that distance, and producing a new motion of the sphere, is thereby conferred upon the magnet; in

this sense, and in this sense only, is the heat converted into magnetic potential energy.

When, therefore, writers on the conservation of energy speak of tensions being 'consumed' and 'generated,'

they do not mean thereby that old attractions have been annihilated and new ones brought into existence, but

that, in the one case, the power of the attraction to produce motion has been diminished by the shortening of

the distance between the attracting bodies, and that in the other case the power of producing motion has been

augmented by the increase of the distance. These remarks apply to all bodies, whether they be sensible

Of the inner quality that enables matter to attract matter we know nothing; and the law of conservation makes

no statement regarding that quality. It takes the facts of attraction as they stand, and affirms only the

constancy of workingpower. That power may exist in the form of MOTION; or it may exist in the form of

FORCE, with distance to act through. The former is dynamic energy, the latter is potential energy, the

constancy of the sum of both being affirmed by the law of conservation. The convertibility of natural forces

consists solely in transformations of dynamic into potential, and of potential into dynamic, energy, which are

incessantly going on. In no other sense has the convertibility of force, at present, any scientific meaning.

By the contraction of a muscle a man lifts a weight from the earth. But the muscle can contract only through

the oxidation of its own tissue or of the blood passing through it. Molecular motion is thus converted into

mechanical motion. Supposing the muscle to contract without raising the weight, oxidation would also occur,

but the whole of the heat produced by this oxidation would be liberated in the muscle itself. Not so when it

performs external work; to do that work a certain definite portion of the heat of oxidation must be expended.

It is so expended in pulling the weight away from the earth. If the weight be permitted to fall, the heat

generated by its collision with the earth would exactly make up for that lacking in the muscle during the

lifting of the weight. In the case here supposed, we have a conversion of molecular muscular action into

potential energy of gravity; and a conversion of that potential energy into heat; the heat, however, appearing

at a distance from its real origin in the muscle. The whole process consists of a transference of molecular

motion from the muscle to the weight, and gravitating force is the mere gobetween, by means of which the

These considerations will help to clear our way to the conception of the transformations which occur when a

wire is moved across the lines of force in a magnetic field. In this case it is commonly said we have a

conversion of magnetism into electricity. But let us endeavour to understand what really occurs. For the sake

of simplicity, and with a view to its translation into a different one subsequently, let us adopt for a moment

the provisional conception of a mixed fluid in the wire, composed of positive and negative electricities in

equal quantities, and therefore perfectly neutralizing each other when the wire is still. By the motion of the

wire, say with the hand, towards the magnet, what the Germans call a ScheidungsKrafta separating

forceis brought into play. This force tears the mixed fluids asunder, and drives them in two currents, the

one positive and the other negative, in two opposite directions through the wire. The presence of these

currents evokes a force of repulsion between the magnet and the wire; and to cause the one to approach the

other, this repulsion must be overcome. The overcoming of this repulsion is, in fact, the work done in

separating and impelling the two electricities. When the wire is moved away from the magnet, a

ScheidungsKraft, or separating force, also comes into play; but now it is an attraction that has to be

surmounted. In surmounting it, currents are developed in directions opposed to the former; positive takes the

place of negative, and negative the place of positive; the overcoming of the attraction being the work done in

The mechanical action occurring here is different from that occurring where a sphere of soft iron is

withdrawn from a magnet, and again attracted. In this case muscular force is expended during the act of

separation; but the attraction of the magnet effects the reunion. In the case of the moving wire also we

overcome a resistance in separating it from the magnet, and thus far the action is mechanically the same as

the separation of the sphere of iron. But after the wire has ceased moving, the attraction ceases; and so far

from any action occurring similar to that which draws the iron sphere back to the magnet, we have to

There is no potential energy conferred either by the removal or by the approach of the wire, and the only

power really transformed or converted, in the experiment, is muscular power. Nothing that could in strictness

be called a conversion of magnetism into electricity occurs. The muscular oxidation that moves the wire fails

to produce within the muscle its due amount of heat, a portion of that heat, equivalent to the resistance

Is this effect an attraction and a repulsion at a distance? If so, why should both cease when the wire ceases to

move? In fact, the deportment of the wire resembles far more that of a body moving in a resisting medium

than anything else; the resistance ceasing when the motion is suspended. Let us imagine the case of a liquid

so mobile that the hand may be passed through it to and fro, without encountering any sensible resistance. It

resembles the motion of a conductor in the unexcited field of an electromagnet. Now, let us suppose a body

placed in the liquid, or acting on it, which confers upon it the property of viscosity; the hand would no longer

move freely. During its motion, but then only, resistance would be encountered and overcome. Here we have

rudely represented the case of the excited magnetic field, and the result in both cases would be substantially

the same. In both cases heat would, in the end, be generated outside of the muscle, its amount being exactly

Let us push the analogy a little further; suppose in the case of the fluid rendered viscous, as assumed a

moment ago, the viscosity not to be so great as to prevent the formation of ripples when the hand is passed

through the liquid. Then the motion of the hand, before its final conversion into heat, would exist for a time

as wavemotion, which, on subsiding, would generate its due equivalent of heat. This intermediate stage, in

the case of our moving wire, is represented by the period during which the electric current is flowing through

it; but that current, like the ripples of our liquid, soon subsides, being, like them, converted into heat.

Do these words shadow forth anything like the reality? Such speculations cannot be injurious if they are

enunciated without dogmatism. I do confess that ideas such as these here indicated exercise a strong

fascination on my mind. Is then the magnetic field really viscous, and if so, what substance exists in it and the

wire to produce the viscosity? Let us first look at the proved effects, and afterwards turn our thoughts back

upon their cause. When the wire approaches the magnet, an action is evoked within it, which travels through

it with a velocity comparable to that of light. One substance only in the universe has been hitherto proved

competent to transmit power at this velocity; the luminiferous ether. Not only its rapidity of progression, but

its ability to produce the motion of light and heat, indicates that the electric current is also motion.[1] Further,

there is a striking resemblance between the action of good and bad conductors as regards electricity, and the

action of diathermanous and adiathermanous bodies as regards radiant heat. The good conductor is

diathermanous to the electric current; it allows free transmission without the development of heat. The bad

conductor is adiathermanous to the electric current, and hence the passage of the latter is accompanied by the

development of heat. I am strongly inclined to hold the electric current, pure and simple, to be a motion of the

ether alone; good conductors being so constituted that the motion may be propagated through their ether

without sensible transfer to their atoms, while in the case of bad conductors this transfer is effected, the

I do not know whether Faraday would have subscribed to what is here written; probably his habitual caution

would have prevented him from committing himself to anything so definite. But some such idea filled his

mind and coloured his language through all the later years of his life. I dare not say that he has been always

successful in the treatment of these theoretic notions. In his speculations he mixes together light and darkness

in varying proportions, and carries us along with him through strong alternations of both. It is impossible to

say how a certain amount of mathematical training would have affected his work. We cannot say what its

influence would have been upon that force of inspiration that urged him on; whether it would have daunted

him, and prevented him from driving his adits into places where no theory pointed to a lode. If so, then we

may rejoice that this strong delver at the mine of natural knowledge was left free to wield his mattock in his

own way. It must be admitted, that Faraday's purely speculative writings often lack that precision which the

mathematical habit of thought confers. Still across them flash frequent gleams of prescient wisdom which

will excite admiration throughout all time; while the facts, relations, principles, and laws which his

experiments have established are sure to form the body of grand theories yet to come.

[1] Mr. Clerk Maxwell has recently published an exceedingly important investigation connected with this

question. Even in the nonmathematical portions of the memoirs of Mr. Maxwell, the admirable spirit of his

philosophy is sufficiently revealed. As regards the employment of scientific imagery, I hardly know his equal

[2] One important difference, of course, exists between the effect of motion in the magnetic field, and motion

in a resisting medium. In the former case the heat is generated in the moving conductor, in the latter it is in

When from an Alpine height the eye of the climber ranges over the mountains, he finds that for the most part

they resolve themselves into distinct groups, each consisting of a dominant mass surrounded by peaks of

lesser elevation. The power which lifted the mightier eminences, in nearly all cases lifted others to an almost

equal height. And so it is with the discoveries of Faraday. As a general rule, the dominant result does not

stand alone, but forms the culminating point of a vast and varied mass of inquiry. In this way, round about his

great discovery of Magnetoelectric Induction, other weighty labours group themselves. His investigations

on the Extra Current; on the Polar and other Condition of Diamagnetic Bodies; on Lines of Magnetic Force,

their definite character and distribution; on the employment of the Induced Magnetoelectric Current as a

measure and test of Magnetic Action; on the Revulsive Phenomena of the magnetic field, are all,

notwithstanding the diversity of title, researches in the domain of Magnetoelectric Induction.

Faraday's second group of researches and discoveries embrace the chemical phenomena of the current. The

dominant result here is the great law of definite Electrochemical Decomposition, around which are massed

various researches on Electrochemical Conduction and on Electrolysis both with the Machine and with the

Pile. To this group also belongs his analysis of the Contact Theory, his inquiries as to the Source of Voltaic

His third great discovery is the Magnetization of Light, which I should liken to the Weisshorn among

The dominant result of his fourth group of researches is the discovery of Diamagnetism, announced in his

memoir as the Magnetic Condition of all Matter, round which are grouped his inquiries on the Magnetism of

Flame and Gases; on Magnecrystallic action, and on Atmospheric Magnetism, in its relations to the annual

and diurnal variation of the needle, the full significance of which is still to be shown.

These are Faraday's most massive discoveries, and upon them his fame must mainly rest. But even without

them, sufficient would remain to secure for him a high and lasting scientific reputation. We should still have

his researches on the Liquefaction of Gases; on Frictional Electricity; on the Electricity of the Gymnotus; on

the source of Power in the Hydroelectric machine, the last two investigations being untouched in the

foregoing memoir; on Electromagnetic Rotations; on Regelation; all his more purely Chemical Researches,

including his discovery of Benzol. Besides these he published a multitude of minor papers, most of which, in

some way or other, illustrate his genius. I have made no allusion to his power and sweetness as a lecturer.

Taking him for all in all, I think it will be conceded that Michael Faraday was the greatest experimental

philosopher the world has ever seen; and I will add the opinion, that the progress of future research will tend,

not to dim or to diminish, but to enhance and glorify the labours of this mighty investigator.

Thus far I have confined myself to topics mainly interesting to the man of science, endeavouring, however, to

treat them in a manner unrepellent to the general reader who might wish to obtain a notion of Faraday as a

worker. On others will fall the duty of presenting to the world a picture of the man. But I know you will

permit me to add to the foregoing analysis a few personal reminiscences and remarks, tending to connect

Faraday with a wider world than that of sciencenamely, with the general human heart.

One word in reference to his married life, in addition to what has been already said, may find a place here. As

in the former case, Faraday shall be his own spokesman. The following paragraph, though written in the third

person, is from his hand:'On June 12, 1821, he married, an event which more than any other contributed to

his earthly happiness and healthful state of mind. The union has continued for twentyeight years and has in

Faraday's immediate forefathers lived in a little place called Clapham Wood Hall, in Yorkshire. Here dwelt

Robert Faraday and Elizabeth his wife, who had ten children, one of them, James Faraday, born in 1761,

being father to the philosopher. A family tradition exists that the Faradays came originally from Ireland.

Faraday himself has more than once expressed to me his belief that his blood was in part Celtic, but how

much of it was so, or when the infusion took place, he was unable to say. He could imitate the Irish brogue,

and his wonderful vivacity may have been in part due to his extraction. But there were other qualities which

we should hardly think of deriving from Ireland. The most prominent of these was his sense of order, which

ran like a luminous beam through all the transactions of his life. The most entangled and complicated matters

fell into harmony in his hands. His mode of keeping accounts excited the admiration of the managing board

of this Institution. And his science was similarly ordered. In his Experimental Researches, he numbered every

paragraph, and welded their various parts together by incessant reference. His private notes of the

Experimental Researches, which are happily preserved, are similarly numbered: their last paragraph bears the

figure 16,041. His working qualities, moreover, showed the tenacity of the Teuton. His nature was impulsive,

but there was a force behind the impulse which did not permit it to retreat. If in his warm moments he formed

a resolution, in his cool ones he made that resolution good. Thus his fire was that of a solid combustible, not

And here I must claim your tolerance for the limits by which I am confined. No materials for a life of Faraday

are in my hands, and what I have now to say has arisen almost wholly out of our close personal relationship.

Letters of his, covering a period of sixteen years, are before me, each one of which contains some

characteristic utterance;strong, yet delicate in counsel, joyful in encouragement, and warm in affection.

References which would be pleasant to such of them as still live are made to Humboldt, Biot, Dumas,

Chevreul, Magnus, and Arago. Accident brought these names prominently forward; but many others would

be required to complete his list of continental friends. He prized the love and sympathy of menprized it

almost more than the renown which his science brought him. Nearly a dozen years ago it fell to my lot to

write a review of his 'Experimental Researches' for the 'Philosophical Magazine.' After he had read it, he took

me by the hand, and said, 'Tyndall, the sweetest reward of my work is the sympathy and good will which it

has caused to flow in upon me from all quarters of the world.' Among his letters I find little sparks of

kindness, precious to no one but myself, but more precious to me than all. He would peep into the laboratory

when he thought me weary, and take me upstairs with him to rest. And if I happened to be absent, he would

leave a little note for me, couched in this or some other similar form: 'Dear Tyndall,I was looking for

you, because we were at tea we have not yet donewill you come up?' I frequently shared his early

dinner; almost always, in fact, while my lectures were going on. There was no trace of asceticism in his

nature. He preferred the meat and wine of life to its locusts and wild honey. Never once during an intimacy of

fifteen years did he mention religion to me, save when I drew him on to the subject. He then spoke to me

without hesitation or reluctance; not with any apparent desire to 'improve the occasion,' but to give me such

information as I sought. He believed the human heart to be swayed by a power to which science or logic

opened no approach, and, right or wrong, this faith, held in perfect tolerance of the faiths of others,

From the letters just referred to, I will select three for publication here. I choose the first, because it contains a

passage revealing the feelings with which Faraday regarded his vocation, and also because it contains an

'My Dear Tyndall,You see by the top of this letter how much habit prevails over me; I have just read yours

from thence, and yet I think myself there. However, I have left its science in very good keeping, and I am

glad to learn that you are at experiment once more. But how is the health? Not well, I fear. I wish you would

get yourself strong first and work afterwards. As for the fruits, I am sure they will be good, for though I

sometimes despond as regards myself, I do not as regards you. You are young, I am old.... But then our

subjects are so glorious, that to work at them rejoices and encourages the feeblest; delights and enchants the

'I have not yet seen anything from Magnus. Thoughts of him always delight me. We shall look at his black

sulphur together. I heard from Schonbein the other day. He tells me that Liebig is full of ozone, i.e., of

The contemplation of Nature, and his own relation to her, produced in Faraday a kind of spiritual exaltation

which makes itself manifest here. His religious feeling and his philosophy could not be kept apart; there was

Whether he or another was its exponent, he appeared to take equal delight in science. A good experiment

would make him almost dance with delight. In November, 1850, he wrote to me thus: 'I hope some day to

take up the point respecting the magnetism of associated particles. In the meantime I rejoice at every addition

to the facts and reasoning connected with the subject. When science is a republic, then it gains: and though I

am no republican in other matters, I am in that.' All his letters illustrate this catholicity of feeling. Ten years

ago, when going down to Brighton, he carried with him a little paper I had just completed, and afterwards

wrote to me. His letter is a mere sample of the sympathy which he always showed to me and my work.

'My Dear Tyndall,I cannot resist the pleasure of saying how very much I have enjoyed your paper. Every

part has given me delight. It goes on from point to point beautifully. You will find many pencil marks, for I

made them as I read. I let them stand, for though many of them receive their answer as the story proceeds, yet

they show how the wording impresses a mind fresh to the subject, and perhaps here and there you may like to

alter it slightly, if you wish the full idea, i.e., not an inaccurate one, to be suggested at first; and yet after all I

believe it is not your exposition, but the natural jumping to a conclusion that affects or has affected my

While once conversing with Faraday on science, in its relations to commerce and litigation, he said to me,

that at a certain period of his career, he was forced definitely to ask himself, and finally to decide whether he

should make wealth or science the pursuit of his life. He could not serve both masters, and he was therefore

compelled to choose between them. After the discovery of magnetoelectricity his fame was so noised

abroad, that the commercial world would hardly have considered any remuneration too high for the aid of

abilities like his. Even before he became so famous, he had done a little 'professional business.' This was the

phrase he applied to his purely commercial work. His friend, Richard Phillips, for example, had induced him

to undertake a number of analyses, which produced, in the year 1830, an addition to his income of more than

a thousand pounds; and in 1831 a still greater addition. He had only to will it to raise in 1832 his professional

business income to 5000L. a year. Indeed double this sum would be a wholly insufficient estimate of what he

might, with ease, have realised annually during the last thirty years of his life.

While restudying the Experimental Researches with reference to the present memoir, the conversation with

Faraday here alluded to came to my recollection, and I sought to ascertain the period when the question,

'wealth or science,' had presented itself with such emphasis to his mind. I fixed upon the year 1831 or 1832,

for it seemed beyond the range of human power to pursue science as he had done during the subsequent

years, and to pursue commercial work at the same time. To test this conclusion I asked permission to see his

accounts, and on my own responsibility, I will state the result. In 1832, his professional business income,

instead of rising to 5000L., or more, fell from 1090L. 4s. to 155L. 9s. From this it fell with slight oscillations

to 92L. in 1837, and to zero in 1838. Between 1839 and 1845, it never, except in one instance, exceeded

22L.; being for the most part much under this. The exceptional year referred to was that in which he and Sir

Charles Lyell were engaged by Government to write a report on the Haswell Colliery explosion, and then his

business income rose to 112L. From the end of 1845 to the day of his death, Faraday's annual professional

business income was exactly zero. Taking the duration of his life into account, this son of a blacksmith, and

apprentice to a bookbinder, had to decide between a fortune of 150,000L. on the one side, and his undowered

science on the other. He chose the latter, and died a poor man. But his was the glory of holding aloft among

The outward and visible signs of fame were also of less account to him than to most men. He had been loaded

with scientific honours from all parts of the world. Without, I imagine, a dissentient voice, he was regarded as

the prince of the physical investigators of the present age. The highest scientific position in this country he

had, however, never filled. When the late excellent and lamented Lord Wrottesley resigned the presidency of

the Royal Society, a deputation from the council, consisting of his Lordship, Mr. Grove, and Mr. Gassiot,

waited upon Faraday, to urge him to accept the president's chair. All that argument or friendly persuasion

could do was done to induce him to yield to the wishes of the council, which was also the unanimous wish of

scientific men. A knowledge of the quickness of his own nature had induced in Faraday the habit of requiring

an interval of reflection, before he decided upon any question of importance. In the present instance he

On the following morning, I went up to his room and said on entering that I had come to him with some

anxiety of mind. He demanded its cause, and I responded:'Lest you should have decided against the wishes

of the deputation that waited on you yesterday.' 'You would not urge me to undertake this responsibility,' he

said. 'I not only urge you,' was my reply, 'but I consider it your bounden duty to accept it.' He spoke of the

labour that it would involve; urged that it was not in his nature to take things easy; and that if he became

president, he would surely have to stir many new questions, and agitate for some changes. I said that in such

cases he would find himself supported by the youth and strength of the Royal Society. This, however, did not

seem to satisfy him. Mrs. Faraday came into the room, and he appealed to her. Her decision was adverse, and

I deprecated her decision. 'Tyndall,' he said at length, 'I must remain plain Michael Faraday to the last; and let

me now tell you, that if I accepted the honour which the Royal Society desires to confer upon me, I would not

answer for the integrity of my intellect for a single year.' I urged him no more, and Lord Wrottesley had a

After the death of the Duke of Northumberland, our Board of Managers wished to see Mr. Faraday finish his

career as President of the Institution, which he had entered on weekly wages more than half a century before.

But he would have nothing to do with the presidency. He wished for rest, and the reverent affection of his

friends was to him infinitely more precious than all the honours of official life.

The first requisite of the intellectual life of Faraday was the independence of his mind; and though prompt to

urge obedience where obedience was due, with every right assertion of manhood he intensely sympathized.

Even rashness on the side of honour found from him ready forgiveness, if not open applause. The wisdom of

years, tempered by a character of this kind, rendered his counsel peculiarly precious to men sensitive like

himself. I often sought that counsel, and, with your permission, will illustrate its character by one or two

In 1855, I was appointed examiner under the Council for Military Education. At that time, as indeed now, I

entertained strong convictions as to the enormous utility of physical science to officers of artillery and

engineers, and whenever opportunity offered, I expressed this conviction without reserve. I did not think the

recognition, though considerable, accorded to physical science in those examinations at all proportionate to

its importance; and this probably rendered me more jealous than I otherwise should have been of its claims.

In Trinity College, Dublin, a school had been organized with reference to the Woolwich examinations, and a

large number of exceedingly wellinstructed young gentlemen were sent over from Dublin, to compete for

appointments in the artillery and the engineers. The result of one examination was particularly satisfactory to

me; indeed the marks obtained appeared so eloquent that I forbore saying a word about them. My colleagues,

however, followed the usual custom of sending in brief reports with their returns of marks. After the results

were published, a leading article appeared in 'The Times,' in which the reports were largely quoted, praise

being bestowed on all the candidates, except the excellent young fellows who had passed through my hands.

A letter from Trinity College drew my attention to this article, bitterly complaining that whereas the marks

proved them to be the best of all, the science candidates were wholly ignored. I tried to set matters right by

publishing, on my own responsibility, a letter in 'The Times.' The act, I knew, could not bear justification

from the War Office point of view; and I expected and risked the displeasure of my superiors. The merited

reprimand promptly came. 'Highly as the Secretary of State for War might value the expression of Professor

Tyndall's opinion, he begged to say that an examiner, appointed by His Royal Highness the

CommanderinChief, had no right to appear in the public papers as Professor Tyndall has done, without the

sanction of the War Office.' Nothing could be more just than this reproof, but I did not like to rest under it. I

wrote a reply, and previous to sending it took it up to Faraday. We sat together before his fire, and he looked

very earnest as he rubbed his hands and pondered. The following conversation then passed between us:

F. You certainly have received a reprimand, Tyndall; but the matter is over, and if you wish to accept the

The letter was firm, but respectful; it acknowledged the justice of the censure, but expressed neither

repentance nor regret. Faraday, in his gracious way, slightly altered a sentence or two to make it more

respectful still. It was duly sent, and on the following day I entered the Institution with the conviction that my

dismissal was there before me. Weeks, however, passed. At length the wellknown envelope appeared, and I

broke the seal, not doubting the contents. They were very different from what I expected. 'The Secretary of

State for War has received Professor Tyndall's letter, and deems the explanation therein given perfectly

satisfactory.' I have often wished for an opportunity of publicly acknowledging this liberal treatment,

proving, as it did, that Lord Panmure could discern and make allowance for a good intention, though it

involved an offence against routine. For many years subsequently it was my privilege to act under that

On another occasion of this kind, having encouraged me in a somewhat hardy resolution I had formed,

Faraday backed his encouragement by an illustration drawn from his own life. The subject will interest you,

and it is so sure to be talked about in the world, that no avoidable harm can rise from its introduction here.

In the year 1835, Sir Robert Peel wished to offer Faraday a pension, but that great statesman quitted office

before he was able to realise his wish. The Minister who founded these pensions intended them, I believe, to

be marks of honour which even proud men might accept without compromise of independence. When,

however, the intimation first reached Faraday in an unofficial way, he wrote a letter announcing his

determination to decline the pension; and stating that he was quite competent to earn his livelihood himself.

That letter still exists, but it was never sent, Faraday's repugnance having been overruled by his friends.

When Lord Melbourne came into office, he desired to see Faraday; and probably in utter ignorance of the

manfor unhappily for them and us, Ministers of State in England are only too often ignorant of great

Englishmenhis Lordship said something that must have deeply displeased his visitor. All the circumstances

were once communicated to me, but I have forgotten the details. The term 'humbug,' I think, was incautiously

employed by his Lordship, and other expressions were used of a similar kind. Faraday quitted the Minister

with his own resolves, and that evening he left his card and a short and decisive note at the residence of Lord

Melbourne, stating that he had manifestly mistaken his Lordship's intention of honouring science in his

person, and declining to have anything whatever to do with the proposed pension. The goodhumoured

nobleman at first considered the matter a capital joke; but he was afterwards led to look at it more seriously.

An excellent lady, who was a friend both to Faraday and the Minister, tried to arrange matters between them;

but she found Faraday very difficult to move from the position he had assumed. After many fruitless efforts,

she at length begged of him to state what he would require of Lord Melbourne to induce him to change his

mind. He replied, 'I should require from his Lordship what I have no right or reason to expect that he would

granta written apology for the words he permitted himself to use to me.' The required apology came, frank

and full, creditable, I thought, alike to the Prime Minister and the philosopher.

Considering the enormous strain imposed on Faraday's intellect, the boylike buoyancy even of his later

years was astonishing. He was often prostrate, but he had immense resiliency, which he brought into action

by getting away from London whenever his health failed. I have already indicated the thoughts which filled

his mind during the evening of his life. He brooded on magnetic media and lines of force; and the great object

of the last investigation he ever undertook was the decision of the question whether magnetic force requires

time for its propagation. How he proposed to attack this subject we may never know. But he has left some

beautiful apparatus behind; delicate wheels and pinions, and associated mirrors, which were to have been

employed in the investigation. The mere conception of such an inquiry is an illustration of his strength and

hopefulness, and it is impossible to say to what results it might have led him. But the work was too heavy for

his tired brain. It was long before he could bring himself to relinquish it and during this struggle he often

suffered from fatigue of mind. It was at this period, and before he resigned himself to the repose which

marked the last two years of his life, that he wrote to me the following letter one of many priceless letters

now before mewhich reveals, more than anything another pen could express, the state of his mind at the

time. I was sometimes censured in his presence for my doings in the Alps, but his constant reply was, 'Let

him alone, he knows how to take care of himself.' In this letter, anxiety on this score reveals itself for the first

'My Dear Tyndall,I do not know whether my letter will catch you, but I will risk it, though feeling very

unfit to communicate with a man whose life is as vivid and active as yours; but the receipt of your kind letter

makes me to know that, though I forget, I am not forgotten, and though I am not able to remember at the end

of a line what was said at the beginning of it, the imperfect marks will convey to you some sense of what I

long to say. We had heard of your illness through Miss Moore, and I was therefore very glad to learn that you

are now quite well; do not run too many risks or make your happiness depend too much upon dangers, or the

hunting of them. Sometimes the very thinking of you, and what you may be about, wearies me with fears, and

then the cogitations pause and change, but without giving me rest. I know that much of this depends upon my

own wornout nature, and I do not know why I write it, save that when I write to you I cannot help thinking

'See what a strange desultory epistle I am writing to you, and yet I feel so weary that I long to leave my desk

'My dear wife and Jane desire their kindest remembrances: I hear them in the next room:... I forgetbut not

This weariness subsided when he relinquished his work, and I have a cheerful letter from him, written in the

autumn of 1865. But towards the close of that year he had an attack of illness, from which he never

completely rallied. He continued to attend the Friday Evening Meetings, but the advance of infirmity was

apparent to us all. Complete rest became finally essential to him, and he ceased to appear among us. There

was no pain in his decline to trouble the memory of those who loved him. Slowly and peacefully he sank

towards his final rest, and when it came, his death was a falling asleep. In the fulness of his honours and of

his age he quitted us; the good fight fought, the work of dutyshall I not say of glory?done. The 'Jane'

referred to in the foregoing letter is Faraday's niece, Miss Jane Barnard, who with an affection raised almost

I saw Mr. Faraday for the first time on my return from Marburg in 1850. I came to the Royal Institution, and

sent up my card, with a copy of the paper which Knoblauch and myself had just completed. He came down

and conversed with me for half an hour. I could not fail to remark the wonderful play of intellect and kindly

feeling exhibited by his countenance. When he was in good health the question of his age would never occur

to you. In the light and laughter of his eyes you never thought of his grey hairs. He was then on the point of

publishing one of his papers on Magnecrystallic action, and he had time to refer in a flattering Note to the

memoir I placed in his hands. I returned to Germany, worked there for nearly another year, and in June, 1851,

came back finally from Berlin to England. Then, for the first time, and on my way to the meeting of the

British Association, at Ipswich, I met a man who has since made his mark upon the intellect of his time; who

has long been, and who by the strong law of natural affinity must continue to be, a brother to me. We were

both without definite outlook at the time, needing proper work, and only anxious to have it to perform. The

chairs of Natural History and of Physics being advertised as vacant in the University of Toronto, we applied

for them, he for the one, I for the other; but, possibly guided by a prophetic instinct, the University authorities

declined having anything to do with either of us. If I remember aright, we were equally unlucky elsewhere.

One of Faraday's earliest letters to me had reference to this Toronto business, which he thought it unwise in

me to neglect. But Toronto had its own notions, and in 1853, at the instance of Dr. Bence Jones, and on the

recommendation of Faraday himself, a chair of Physics at the Royal Institution was offered to me. I was

tempted at the same time to go elsewhere, but a strong attraction drew me to his side. Let me say that it was

mainly his and other friendships, precious to me beyond all expression, that caused me to value my position

here more highly than any other that could be offered to me in this land. Nor is it for its honour, though surely

that is great, but for the strong personal ties that bind me to it, that I now chiefly prize this place. You might

not credit me were I to tell you how lightly I value the honour of being Faraday's successor compared with

the honour of having been Faraday's friend. His friendship was energy and inspiration; his 'mantle' is a

Sometimes during the last year of his life, by the permission or invitation of Mrs. Faraday, I went up to his

rooms to see him. The deep radiance, which in his time of strength flashed with such extraordinary power

from his countenance, had subsided to a calm and kindly light, by which my latest memory of him is warmed

and illuminated. I knelt one day beside him on the carpet and placed my hand upon his knee; he stroked it

affectionately, smiled, and murmured, in a low soft voice, the last words that I remember as having been

It was my wish and aspiration to play the part of Schiller to this Goethe: and he was at times so strong and

joyfulhis body so active, and his intellect so clearas to suggest to me the thought that he, like Goethe,

would see the younger man laid low. Destiny ruled otherwise, and now he is but a memory to us all. Surely

no memory could be more beautiful. He was equally rich in mind and heart. The fairest traits of a character

sketched by Paul, found in him perfect illustration. For he was 'blameless, vigilant, sober, of good behaviour,

apt to teach, not given to filthy lucre.' He had not a trace of worldly ambition; he declared his duty to his

Sovereign by going to the levee once a year, but beyond this he never sought contact with the great. The life

of his spirit and of his intellect was so full, that the things which men most strive after were absolutely

indifferent to him. 'Give me health and a day,' says the brave Emerson, 'and I will make the pomp of

emperors ridiculous.' In an eminent degree Faraday could say the same. What to him was the splendour of a

palace compared with a thunderstorm upon Brighton Downs?what among all the appliances of royalty to

compare with the setting sun? I refer to a thunderstorm and a sunset, because these things excited a kind of

ecstasy in his mind, and to a mind open to such ecstasy the pomps and pleasures of the world are usually of

small account. Nature, not education, rendered Faraday strong and refined. A favourite experiment of his own

was representative of himself. He loved to show that water in crystallizing excluded all foreign ingredients,

however intimately they might be mixed with it. Out of acids, alkalis, or saline solutions, the crystal came

sweet and pure. By some such natural process in the formation of this man, beauty and nobleness coalesced,

to the exclusion of everything vulgar and low. He did not learn his gentleness in the world, for he withdrew

himself from its culture; and still this land of England contained no truer gentleman than he. Not half his

greatness was incorporate in his science, for science could not reveal the bravery and delicacy of his heart.

But it is time that I should end these weak words, and lay my poor garland on the grave of this