Michael Faraday

He could scarcely pass a gold leaf electrometer without causing the leaves to diverge by a sudden flick from his silk handkerchief. I recollect, too, his meeting me at the entrance to the lecture theatre at Jermyn Street, when Lyon Playfair was to give the first, or one of the first lectures ever delivered in the building. "Let us go up here," said he, leading me far away from the central table. I asked him why he chose such an out-of-the-way place. "Oh," he replied, "we shall be able here to find out what are the acoustic qualities of the room."

The simplicity of the means with which he made his experiments was often astonishing, and was indeed one of the manifestations of his genius.

A good instance is thus narrated by Sir Frederick Arrow. "When the electric light was first exhibited permanently at Dungeness, on 6th June, 1862, a committee of the Elder Brethren, of which I was one, accompanied Faraday to observe it. We dined, I think, at Dover, and embarked in the yacht from there, and were out for some hours watching it, to Faraday's great delight – (a very fine night) – and especially we did so from the Varne lightship, about equidistant between it and the French light of Grisnez, using all our best glasses and photometers to ascertain the relative value of the lights: and this brings me to my story. Before we left Dover, Faraday, with his usual bright smile, in great glee showed me a little common paper box, and said, 'I must take care of this; it's my special photometer,' – and then, opening it, produced a lady's ordinary black shawl-pin, – jet, or imitation perhaps, – and then holding it a little way off the candle, showed me the image very distinct; and then, putting it a little further off, placed another candle near it, and the relative distance was shown by the size of the image. He lent me this afterwards when we were at the Varne lightship, and it acted admirably; and ever since I have used one as a very convenient mode of observing, and I never do so but I think of that night and dear good Faraday, and his genial happy way of showing how even common things may be made useful." After this Faraday modified his glass-bead photometer, and he might be seen comparing the relative intensity of two lights by watching their luminous images on a bead of black glass, which he had threaded on a string, and was twirling round so as to resolve the brilliant points into circles of fainter light; or he fixed the black glass balls on pieces of cork, and, attaching them to a little wheel, set them spinning for the same purpose. Some of these beads are preserved by the Trinity House, with other treasures of a like kind, including a flat piece of solder of an irregular oval form, turned up at one side so as to form a thumb-rest, and which served the philosopher as a candlestick to support the wax-light that he used as a standard. The museum of the Royal Institution contains a most instructive collection of his experimental apparatus, including the common electrical machine which he made while still an apprentice at Riebau's, and the ring of soft iron, with its twisted coils of wire isolated by calico and tied with common string, by means of which he first obtained electrical effects from a magnet.

In lecturing to the young he delighted to show how easily apparatus might be extemporized. Thus, in order to construct an electrical machine he once inverted a four-legged stool to serve for the stand, and took a white glass bottle for the cylinder. A cork was fitted into the mouth of this bottle, and a bung was fastened with sealing-wax to the other end: into the cork was inserted a handle for rotating the bottle, and in the centre of the bung was a wooden pivot on which it turned; while with some stout wire he made crutches on two of the legs of the stool for the axles of this glass cylinder to work upon. The silk rubber he held in his hand. A japanned tin tea-canister resting on a glass tumbler formed the conductor, and the collector was the head of a toasting fork. With this apparently rough apparatus he exhibited all the rudimentary experiments in electricity to a large audience.

Wishing to carry home in good condition a flower that had been given him, he rolled a piece of writing-paper round a cork, tied it tightly with string, and filled the little tube with water. He had thus a perfectly efficient bouquet-holder.

A lady, calling on his wife, happened to mention that a needle had been once broken into her foot, and she did not know whether it had been all extracted or not. "Oh!" said Faraday, "I will soon tell you that," – and taking a finely suspended magnetic needle, he held it close to her foot, and it dipped to the concealed iron.

On this subject Schönbein has also some good remarks. "The laboratory of the Institution is indeed efficiently arranged, though anything but large and elaborately furnished. And yet something extraordinary has happened in this room for the extension of the limits of knowledge; and already more has been done in it than in many other institutions where the greatest luxury in the supply of apparatus prevails, and where there is the greatest command of money. But when men work with the creative genius of a Davy, and the intuitive spirit of investigation and the wealth of ideas of a Faraday, important and great things must come to pass, even though the appliances at command should be of so limited a character. For the experimental investigator of nature, it is especially desirable that, according to the kind of his researches, he should have at command such and such appliances, that he should possess a 'philosophical apparatus,' a laboratory, &c.; but for the purpose of producing something important, of greatly widening the sphere of knowledge, it in no way follows that a superfluity of such things is necessary to him… He who understands how to put appropriate questions to Nature, generally knows how to extract the answers by simple means; and he who wants this capacity will, I fear, obtain no profitable result, even though all conceivable tools and apparatus may be ready to his hand."

Nor did Faraday require elaborate apparatus to illustrate his meaning. Steaming up the Thames one July day in a penny boat, he was struck with the offensiveness of the water. He tore some white cards into pieces, wetted them so as to make them sink easily, and dropped them into the river at each pier they came to. Their sudden disappearance from sight, though the sun was shining brightly, was proof enough of the impurity of the stream; and he wrote a letter to the Times describing his observations, and calling public attention to the dangerous state of the river.[20 - Punch's cartoon next week represented Professor Faraday holding his nose, and presenting his card to Father Thames, who rises out of the unsavoury ooze.] At a meeting of the British Association he wished to explain the manner in which certain crystallized bodies place themselves between the poles of an electro-magnet: two or three raw potatoes furnished the material out of which he cut admirable models of the crystals. Wishing to show the electrical nature of gun-cotton, he has been known to lay his watch upon the table, balance on it a slender piece of wood, and, charging a morsel of the gun-cotton by drawing it along his coat sleeve, cause the wood to revolve towards the electric fibres.

"An artist was once maintaining that in natural appearances and in pictures, up and down, and high and low, were fixed indubitable realities; but Faraday told him that they were merely conventional acceptations, based on standards often arbitrary. The disputant could not be convinced that ideas which he had hitherto never doubted had such shifting foundations. 'Well,' said Faraday, 'hold a walking-stick between your chin and your great toe; look along it and say which is the upper end.' The experiment was tried, and the artist found his idea of perspective at complete variance with his sense of reality; either end of the stick might be called 'upper,' – pictorially it was one, physically it was the other."

Faraday's manner of experimenting may be further illustrated by the recollections of other friends who have had the opportunity of watching him at work.

Mr. James Young, who was in the laboratory of University College in 1838, thus writes: – "About that time Professor Graham had got from Paris Thilorier's apparatus for producing liquid and solid carbonic acid; hearing of this, Mr. Faraday came to Graham's laboratory, and, as one might expect, showed great interest in this apparatus, and asked Graham for the loan of it for a Friday evening lecture at the Royal Institution, which of course Graham readily granted, and Faraday asked me to come down to the Institution and give him the benefit of my experience in charging and working the apparatus; so I spent a long evening at the Royal Institution laboratory. There was no one present but Faraday, Anderson, and myself. The principal thing we did was to charge the apparatus and work with the solid carbonic acid, Mr. Faraday working with great activity; his motions were wonderfully rapid; and if he had to cross the laboratory for anything, he did not walk at an ordinary step, but ran for it, and when he wanted anything he spoke quickly. Faraday had a theory at that time that all metals would become magnetic if their temperature were low enough; and he tried that evening some experiments with cobalt and manganese, which he cooled in a mixture of carbonic acid and ether, but the results were negative."

Among the deep mines of the Durham coal-field is one called the Haswell Colliery. One Saturday afternoon, while the men were at work in it as usual, a terrible explosion occurred: it proceeded from the fire-damp that collects in the vaulted space that is formed in old workings, when the supporting pillars of coal are removed and the roof falls in: the suffocating gases rushed along the narrow passages, and overwhelmed ninety-five poor fellows with destruction. Of course there was an inquiry, and the Government sent down to the spot as their commissioners Professor Faraday and Sir Charles Lyell. The two gentlemen attended at the coroner's inquest, where they took part in the examination of the witnesses; they inspected the shattered safety-lamps; they descended into the mine, spending the best part of a day in the damaged and therefore dangerous galleries where the catastrophe had occurred, and they did not leave without showing in a practical form their sympathy with the sufferers. When down in the pit, an inspector showed them the way in which the workmen estimated the rapidity of the ventilation draught, by throwing a pinch of gunpowder through the flame of a candle, and timing the movement of the little puff of smoke. Faraday, not admiring the free and easy way in which they handled their powder, asked where they kept their store of it, and learnt that it was in a large black bag which had been assigned to him as the most comfortable seat they could offer. We may imagine the liveliness with which he sprang to his feet, and expostulated with them on their culpable carelessness.

My own opportunities of observing Faraday at work were nearly confined to a series of experiments, which are the better worth describing here as they have escaped the notice of previous biographers. The Royal Commission appointed to inquire into our whole system of Lights, Buoys, and Beacons, perceived a great defect that rendered many of our finest shore or harbour lights comparatively ineffective. The great central lamp in a lighthouse is surrounded by a complicated arrangement of lenses and prisms, with the object of gathering up as many of the rays as possible and sending them over the surface of the sea towards the horizon. Now, it is evident that if this apparatus be adjusted so as to send the beam two or three degrees upwards, the light will be lost to the shipping and wasted on the clouds; and if two or three degrees downwards, it will only illuminate the water in the neighbourhood: in either case the beautiful and expensive apparatus would be worse than useless. It is evident also that if the eye be placed just above the wick of the lamp, it will see through any particular piece of glass that very portion of the landscape which will be illuminated by a ray starting from the same spot; or the photographic image formed in the place of the flame by any one of the lenses will tell us the direction in which that lens will throw the luminous rays. This simple principle was applied by the Commissioners for testing the adjustment of the apparatus in the different lights, and it was found that few were rightly placed, or rather that no method of adjustment was in use better than the mason's plumbline. The Royal Commissioners therefore in 1860 drew the attention of all the lighthouse authorities to this fact, and asked the Elder Brethren of the Trinity House, with Faraday and other parties, to meet them at the lights recently erected at the North Foreland and Whitby. I, as the scientific member of the Commission, had drawn out in detail the course of rays from different parts of the flame, through different parts of the apparatus, and I was struck with the readiness with which Faraday, who had never before considered the matter,[21 - Since writing the above I have come across a letter written by Faraday in answer to one by Captain Welier as far back as 13th Sept. 1839, in which he pointed out the mal-adjustment of the dioptric apparatus at Orfordness. In July of the following year he made lengthy suggestions to the Trinity House, in which he proposed using a flat white circle or square, half an inch across, on a piece of black paper or card, as a "focal object." This was to be looked at from outside, in order to test the regularity of the glass apparatus. He also suggested observations on the divergence by looking at this white circle at a distance of twenty feet at most. Another plan he proposed was that of lighting the lamp and putting up a white screen outside. These methods of examining he carried out very shortly afterwards at Blackwall, on French and English refractors, but it seems never to have occurred to him to place his eye in the focus, or in any other manner to observe the course of the rays from inside the apparatus.] took up the idea, and recognized its importance and its practical application. With his characteristic ingenuity, too, he devised a little piece of apparatus for the more exact observation of the matter inside the lighthouse. He took to Mr. Ladd, the optical instrument maker, a drawing, very neatly executed, with written directions, and a cork cut into proper shape with two lucifer matches stuck through it, to serve as a further explanation of his meaning: and from this the "focimeter," as he called it, was made. The position of the glass panels at Whitby was corrected by means of this little instrument, and there were many journeys down to Chance's glassworks near Birmingham, where, declining the hospitality of the proprietor in order to be absolutely independent, he put up at a small hotel while he made his experiments, and jotted down his observations on the cards he habitually carried in his pocket. At length we were invited down to see the result. Faraday explained carefully all that had been done, and at the risk of sea-sickness (no trifling matter in his case) accompanied us out to sea to observe the effect from various directions and at various distances. The experience acquired at Whitby was applied elsewhere, and in May 1861 the Trinity House appointed a Visiting Committee, "to examine all dioptric light establishments, with the view of remedying any inaccuracies of arrangement that may be found to exist." Faraday had instructed and practised Captain Nisbet and some others of the Elder Brethren in the use of the focimeter, and now wrote a careful letter of suggestions on the question of adjustment between the lamp and the lenses and prisms; so thoughtfully did he work for the benefit of those who "go down to the sea in ships, that do business in great waters."

As to the mental process that devised, directed, and interpreted his experiments, it must be borne in mind that Faraday was no mathematician; his power of appreciating an à priori reason often appeared comparatively weak. "It has been stated on good authority that Faraday boasted on a certain occasion of having only once in the course of his life performed a mathematical calculation: that once was when he turned the handle of Babbage's calculating machine."[22 - Dr. Scoffern, Belgravia, October 1867.] Though there was more pleasantry than truth in this professed innocence of numbers, probably no one acquainted with his electrical researches will doubt that, had he possessed more mathematical ability, he would have been saved much trouble, and would sometimes have expressed his conclusions with greater ease and precision. Yet, as Sir William Thomson has remarked with reference to certain magnetic phenomena, "Faraday, without mathematics, divined the result of the mathematical investigation; and, what has proved of infinite value to the mathematicians themselves, he has given them an articulate language in which to express their results. Indeed, the whole language of the magnetic field and 'lines of force' is Faraday's. It must be said for the mathematicians that they greedily accepted it, and have ever since been most zealous in using it to the best advantage."

The peculiarity of his mind was indeed well known to himself. In a letter to Dr. Becker he says: "I was never able to make a fact my own without seeing it; and the descriptions of the best works altogether failed to convey to my mind such a knowledge of things as to allow myself to form a judgment upon them. It was so with new things. If Grove, or Wheatstone, or Gassiot, or any other told me a new fact, and wanted my opinion either of its value, or the cause, or the evidence it could give on any subject, I never could say anything until I had seen the fact. For the same reason I never could work, as some Professors do most extensively, by students or pupils. All the work had to be my own."

Thus we are told what took place "when Dr. Tyndall brought Mr. Faraday into the laboratory to look at his new discovery of calorescence. As Faraday saw for the first time a piece of cold, black platinum raised to a dazzling brightness when held in the focus of dark rays, a point undistinguishable from the air around, he looked on attentively, putting on his spectacles to observe more carefully, then ascertained the conditions of the experiment, and repeated it for himself; and now quite satisfied, he turned with emotion to Dr. Tyndall, and almost hugged him with pleasure."[23 - Mr. Barrett, Nature, Sept. 19, 1872.]

The following story by Mr. Robert Mallet also serves as an illustration: – "It must be now eighteen years ago when I paid him a visit and brought some slips of flexible and tough Muntz's yellow metal, to show him the instantaneous change to complete brittleness with rigidity produced by dipping into pernitrate of mercury solution. He got the solution, and I showed him the facts; he obviously did not doubt what he saw me do before and close to him: but a sort of experimental instinct seemed to require he should try it himself. So he took one of the slips, bent it forwards and backwards, dipped it, and broke it up into short bits between his own fingers. He had not before spoken. Then he said, 'Yes, it is pliable, and it does become instantly brittle.' And after a few moments' pause he added, 'Well, now have you any more facts of the sort?' and seemed a little disappointed when I said, 'No; none that are new.' It has often since occurred to me how his mind needed absolute satisfaction that he had grasped a fact, and then instantly rushed to colligate it with another if possible."

But as the Professor watched these new facts, new thoughts would shape themselves in his mind, and this would lead to fresh experiments in order to test their truth. The answers so obtained would lead to further questions. Thus his work often consisted in the defeat of one hypothesis after another, till the true conditions of the phenomena came forth and claimed the assent of the experimenter and ultimately of the scientific world.

A. de la Rive has some acute observations on this subject. He explains how Faraday did not place himself before his apparatus, setting it to work, without a preconceived idea. Neither did he take up known phenomena, as some scientific men do, and determine their numerical data, or study with great precision the laws which regulate them. "A third method, very different from the preceding, is that which, quitting the beaten track, leads, as if by inspiration, to those great discoveries which open new horizons to science. This method, in order to be fertile, requires one condition – a condition, it is true, which is but rarely met with – namely, genius. Now, this condition existed in Faraday. Endowed, as he himself perceived, with much imagination, he dared to advance where many others would have recoiled: his sagacity, joined to an exquisite scientific tact, by furnishing him with a presentiment of the possible, prevented him from wandering into the fantastic; while, always wishing only for facts, and accepting theories only with difficulty, he was nevertheless more or less directed by preconceived ideas, which, whether true or false, led him into new roads, where most frequently he found what he sought, and sometimes also what he did not seek, but where he constantly met with some important discovery.

"Such a method, if indeed it can be called one, although barren and even dangerous with mediocre minds, produced great things in Faraday's hands; thanks, as we have said, to his genius, but thanks also to that love of truth which characterized him, and which preserved him from the temptation so often experienced by every discoverer, of seeing what he wishes to see, and not seeing what he dreads."

This love of truth deserves a moment's pause. It was one of the most beautiful and most essential of his characteristics; it taught him to be extremely cautious in receiving the statements of others or in drawing his own conclusions,[24 - A good instance of his caution in drawing conclusions is contained in one of his letters to me: —"Royal Institution of Great Britain,"2 July, 1859."My dear Gladstone,"Although I have frequently observed lights from the sea, the only thing I have learnt in relation to their relative brilliancy is that the average of a very great number of observations would be required for the attainment of a moderate approximation to truth. One has to be some miles off at sea, or else the observation is not made in the chief ray, and then one does not know the state of the atmosphere about a given lighthouse. Strong lights like that of Cape Grisnez have been invisible when they should have been strong; feeble lights by comparison have risen up in force when one might have expected them to be relatively weak; and after inquiry has not shown a state of the air at the lighthouse explaining such differences. It is probable that the cause of difference often exists at sea."Besides these difficulties there is that other great one of not seeing the two lights to be compared in the field of view at the same time and same distance. If the eye has to turn 90° from one to the other, I have no confidence in the comparison; and if both be in the field of sight at once, still unexpected and unexplained causes of difference occur. The two lights at the South Foreland are beautifully situated for comparison, and yet sometimes the upper did not equal the lower when it ought to have surpassed it. This I referred at the time to an upper stratum of haze; but on shore they knew nothing of the kind, nor had any such or other reason to expect particular effects."Ever truly yours,"M. Faraday."As an instance of his unwillingness to commit himself to an opinion unless he was sure about it, may be cited a letter he wrote to Sir G. B. Airy, the Astronomer Royal, who asked for his advice in regard to the material of which the national standard of length should be made: – "I do not see any reason why a pure metal should be particularly free from internal change of its particles, and on the whole should rather incline to the hard alloy than to soft copper, and yet I hardly know why. I suppose the labour would be too great to lay down the standard on different metals and substances; and yet the comparison of them might be very important hereafter, for twenty years seem to do or tell a great deal in relation to standard measures." Bronze was finally chosen.] and it led him, if his scepticism was overcome, to adopt at once the new view, and to maintain it, if need be, against the world.

"The thing I am proudest of, Pearsall, is that I have never been found to be wrong," he could say in the early part of his scientific history without fear of contradiction. After his death A. de la Rive wrote, "I do not think that Faraday has once been caught in a mistake; so precise and conscientious was his mode of experimenting and observing." This is not absolutely true; but the extreme rarity of his mistakes, notwithstanding the immense amount of his published researches, is one of those marvels which can be appreciated only by those who are in the habit of describing what they have seen in the mist land that lies beyond the boundaries of previous knowledge.

Into this unknown region his mental vision was ever stretched. "I well remember one day," writes Mr. Barrett, a former assistant at the Royal Institution, "when Mr. Faraday was by my side, I happened to be steadying, by means of a magnet, the motion of a magnetic needle under a glass shade. Mr. Faraday suddenly looked most impressively and earnestly as he said, 'How wonderful and mysterious is that power you have there! the more I think over it the less I seem to know:' – and yet he who said this knew more of it than any living man."

It is easy to imagine with what wonder he would stand before the apples or leaves or pieces of meat that swung round into a transverse position between the poles of his gigantic magnet, or the sand that danced and eddied into regular figures on plates of glass touched by the fiddle-bow, or gold so finely divided that it appeared purple and when diffused in water took a twelvemonth to settle. It is easy, too, to imagine how he would long to gain a clear idea of what was taking place behind the phenomena. But it is far from easy to grasp the conceptions of his brain: language is a clumsy vehicle for such thoughts. He strove to get rid of such figurative terms as "currents" and "poles;" in discussing the mode of propagation of light and radiant heat he endeavoured "to dismiss the ether, but not the vibrations;" and in conceiving of atoms, he says: "As to the little solid particles … I cannot form any idea of them apart from the forces, so I neither admit nor deny them. They do not afford me the least help in my endeavour to form an idea of a particle of matter. On the contrary, they greatly embarrass me." Yet he could not himself escape from the tyranny of words or the deceitfulness of metaphors, and it is hard for his readers to comprehend what was his precise idea of those centres of forces that occupy no space, or of those lines of force which he beheld with his mental eye, curving alike round his magnetic needle, and that mightiest of all magnets – the earth.

As he was jealous of his own fame, and had learnt by experience that discoveries could be stolen, he talked little about them till they were ready for the public; indeed, he has been known to twit a brother electrician for telling his discoveries before printing them, adding with a knowing laugh, "I never do that." He was obliged, however, to explain his results to Professor Whewell, or some other learned friend, if he wished to christen some new idea with a Greek name. One of Whewell's letters on such an occasion, dated Trinity College, Cambridge, October 14, 1837, begins thus: —

"My dear Sir,

"I am always glad to hear of the progress of your researches, and never the less so because they require the fabrication of a new word or two. Such a coinage has always taken place at the great epochs of discovery; like the medals that are struck at the beginning of a new reign, or rather like the change of currency produced by the accession of a new Sovereign; for their value and influence consists in their coming into common circulation."

During the whole time of an investigation Faraday had kept ample notes, and when all was completed he had little to do but to copy these notes, condensing or re-arranging some parts, and omitting what was useless. The paper then usually consisted of a series of numbered paragraphs, containing first a statement of the subject of inquiry, then a series of experiments giving negative results, and afterwards the positive discoveries. In this form it was sent to the Royal Society or some other learned body. Yet this often involved considerable labour, as the following words written to Miss Moore in 1850 from a summer retreat in Upper Norwood will show: – "I write and write and write, until nearly three papers for the Royal Society are nearly completed, and I hope that two of them will be good if they do justify my hopes, for I have to criticise them again and again before I let them loose. You shall hear of them at some of the next Friday evenings."

This criticism did not cease with their publication, for he endeavoured always to improve on his previous work. Thus, in 1832 he bound his papers together in one volume, and the introduction on the fly-leaf shows the object with which it was done: —

"Papers of mine, published in octavo, in the Quarterly Journal of Science, and elsewhere, since the time that Sir H. Davy encouraged me to write the analysis of caustic lime.

"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 me – and none more than the bad – in pointing out to me in future, or rather after times, the faults it became me to watch and to avoid.

"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.

    "M. Faraday.

"August 18, 1832."

This section may be summed up in the words of Dumas when he gave the first "Faraday Lecture" of the Chemical Society: – "Faraday is the type of the most fortunate and the most accomplished of the learned men of our age. His hand in the execution of his conceptions kept pace with his mind in designing them; he never wanted boldness when he undertook an experiment, never lacked resources to ensure success, and was full of discretion in interpreting results. His hardihood, which never halted when once he had undertaken a task, and his wariness, which felt its way carefully in adopting a received conclusion, will ever serve as models for the experimentalist."

SECTION V

THE VALUE OF HIS DISCOVERIES

Science is pursued by different men from different motives.

"To some she is the goddess great;
To some the milch-cow of the field;
Their business is to calculate
The butter she will yield."

Now, Faraday had been warned by Davy before he entered his service that Science was a mistress who paid badly; and in 1833 we have seen him deliberately make his calculation, give up the butter, and worship the goddess.

For the same reason also he declined most of the positions of honour which he was invited to fill, believing that they would encroach too much on his time, though he willingly accepted the honorary degrees and scientific distinctions that were showered upon him.[25 - De la Rive points this out in his brief notice of Faraday immediately on receiving the news of his death: – "Je n'ai parlé que du savant, je tiens aussi à dire un mot de l'homme. Alliant à une modestie vraie, parcequ'elle provenait de l'élévation de son âme, une droiture à toute épreuve et une candeur admirable, Faraday n'aimait la science que pour elle-même. Aussi jouissait-il des succès des autres au moins autant que des siens propres; et quant à lui, s'il a accepté, avec une sincère satisfaction, les honneurs scientifiques qui lui out été prodigués à si juste titre, il a constamment refusé toutes les autres distinctions et les récompenses qu'on eût voulu lui décerner. Il s'est contenté toute sa vie de la position relativement modeste qu'il occupait à l'Institution Royale de Londres; avoir son laboratoire et strictement de quoi vivre, c'est tout ce qu'il lui fallait. – Presinge, le 29 août, 1867. – A. de la Rive."]

And among those who follow Science lovingly, there are two very distinct bands: there are the philosophers, the discoverers, men who persistently ask questions of Nature; and there are the practical men, who apply her answers to the various purposes of human life. Many noble names are inscribed in either bead-roll, but few are able to take rank in both services: indeed, the question of practical utility would terribly cramp the investigator, while the enjoyment of patient research in unexplored regions of knowledge is usually too ethereal for those who seek their pleasures in useful inventions. The mental configuration is different in the two cases; each may claim and receive his due award of honour.

Faraday was pre-eminently a discoverer; he liked the name of "philosopher." His favourite paths of study seem to wander far enough from the common abodes of human thought or the requirements of ordinary life. He became familiar, as no other man ever was, with the varied forces of magnetism and electricity, heat and light, gravitation and galvanism, chemical affinity and mechanical motion; but he did not seek to "harness the lightnings," or to chain those giants and to make them grind like Samson in the prison-house. His way of treating them reminds us rather of the old fable of Proteus, who would transform himself into a whirlwind or a dragon, a flame of fire or a rushing stream, in order to elude his pursuer; but if the wary inquirer could catch him asleep in his cave, he might be constrained to utter all his secret knowledge: for the favourite thought of Faraday seems to have been that these various forces were the changing forms of a Proteus, and his great desire seems to have been to learn the secret of their origin and their transformations. Thus he loved to break down the walls of separation between different classes of phenomena, and his eye doubtless sparkled with delight when he saw what had always been looked upon as permanent gases liquefy like common vapours under the constraint of pressure and cold – when the wires that coiled round his magnets gave signs of an electric wave, or coruscated with sparks – when the electricities derived from the friction machine and from the voltaic pile yielded him the same series of phenomena – when he recognized the cumulative proof that the quantity of electricity in a galvanic battery is exactly proportional to the chemical action – when his electro-static theory seemed to break down the barrier between the conductors and insulators, and many other barriers beside – when he sent a ray of polarized light through a piece of heavy glass between the poles of an electro-magnet, and on making contact saw that the plane of polarization was rotated, or, as he said, the light was magnetized – and when he watched pieces of bismuth, or crystals of Iceland spar, or bubbles of oxygen, ranging themselves in a definite position in the magnetic field.

"I delight in hearing of exact numbers, and the determinations of the equivalents of force when different forms of force are compared one with another," he wrote to Joule in 1845; and no wonder, for these quantitative comparisons have proved many of his speculations to be true, and have made them the creed of the scientific world. When he began to investigate the different sciences, they might be compared to so many different countries with impassable frontiers, different languages and laws, and various weights and measures; but when he ceased they resembled rather a brotherhood of states, linked together by a community of interests and of speech, and a federal code; and in bringing about this unification no one had so great a share as himself.

He loved to speculate, too, on Matter and Force, on the nature of atoms and of imponderable agents. "It is these things," says the great German physicist Professor Helmholz, "that Faraday, in his mature works, ever seeks to purify more and more from everything that is theoretical, and is not the direct and simple expression of the fact. For instance, he contended against the action of forces at a distance, and the adoption of two electrical and two magnetic fluids, as well as all hypotheses contrary to the law of the conservation of force, which he early foresaw, though he misunderstood it in its scientific expression. And it is just in this direction that he exercised the most unmistakeable influence first of all on the English physicists."[26 - Preface to "Faraday und seine Entdeckungen."]

While, however, Faraday was pre-eminently an experimental philosopher, he was far from being indifferent to the useful applications of science. His own connection with the practical side of the question was threefold: he undertook some laborious investigations of this nature himself; he was frequently called upon, especially by the Trinity House, to give his opinions on the inventions of others; and he was fond of bringing useful inventions before the members of the Royal Institution in his Friday evening discourses. The first of these, on February 3, 1826, was on India-rubber, and was illustrated by an abundance of specimens both in the raw and manufactured states. He traced the history of the substance, from the crude uncoagulated sap to the sheet rubber and waterproof fabrics which Mr. Hancock and Mr. Macintosh had recently succeeded in preparing. In this way also he continued to throw the magic of his genius around Morden's machinery for manufacturing Bramah's locks, Ericsson's caloric engine, Brunel's block machinery at Portsmouth, Petitjean's process for silvering mirrors, the prevention of dry-rot in timber, De la Rue's envelope machinery, artificial rubies, Bonelli's electric silk loom, Barry's mode of ventilating the House of Lords, and many kindred subjects.

It may not be amiss to describe the last of his Friday evenings, in which he brought before the public Mr. C. W. Siemens' Regenerative Gas Furnace. The following letter to the inventor will tell the first steps: —

    "Royal Institution, March 22, 1862.

"My dear Sir,