Inventors, and promoters of useful inventions, frequently benefited by the advice of Faraday, or by his generous help. A remarkable instance of this was told me by Cyrus Field. Near the commencement of his great enterprise, when he wished to unite the old and the new worlds by the telegraphic cable, he sought the advice of the great electrician, and Faraday told him that he doubted the possibility of getting a message across the Atlantic. Mr. Field saw that this fatal objection must be settled at once, and begged Faraday to make the necessary experiments, offering to pay him properly for his services. The philosopher, however, declined all remuneration, but worked away at the question, and presently reported to Mr. Field:—"It can be done, but you will not get an instantaneous message." "How long will it take?" was the next inquiry. "Oh, perhaps a second." "Well, that's quick enough for me," was the conclusion of the American; and the enterprise was proceeded with.
As to the electric telegraph itself, Faraday does not appear among those who claim its parentage, but he was constantly associated with those who do; his criticisms led Ritchie to develop more fully his early conception, and he was constantly engaged with batteries and wires and magnets, while the telegraph was being perfected by others, and especially by his friend Wheatstone, whose name will always be associated with what is perhaps the most wonderful invention of modern times.
As to Faraday's own work in applied science, his attempts to improve the manufacture of steel, and afterwards of glass for optical purposes, were among the least satisfactory of his researches. He was more successful in the matter of ventilation of lamp-burners. The windows of lighthouses were frequently found streaming with water that arose from the combustion of the oil, and in winter this was often converted into thick ice. He devised a plan by which this water was effectually carried away, and the room was also made more healthy for the keepers. At the Athenæum Club serious complaints were made that the brilliantly lighted drawing-room became excessively hot, and that headaches were very common, while the bindings of the books were greatly injured by the sulphuric acid that arose from the burnt coal-gas. Faraday cured this by an arrangement of glass cylinders over the ordinary lamp chimneys, and descending tubes which carried off the whole products of combustion without their ever mixing with the air of the room. This principle could of course be applied to brackets or chandeliers elsewhere, but the Professor made over any pecuniary benefit that might accrue from it to his brother, who was a lamp manufacturer, and had aided him in the invention.
The achievements of Faraday are certainly not to be tested by a money standard, nor by their immediate adaptation to the necessities or conveniences of life. "Practical men" might be disposed to think slightly of the grand discoveries of the philosopher. Their ideas of "utility" will probably be different. One man may take his wheat corn and convert it into loaves of bread, while his neighbour appears to lose his labour by throwing the precious grain into the earth: but which is after all most productive? The loaves will at once feed the hungry, but the sower's toil will be crowned in process of time by waving harvests.
Yet some of Faraday's most recondite inquiries did bear practical fruit even during his own lifetime. In proof of this I will take one of his chemical and two of his electrical discoveries.
Long ago there was a Portable Gas Company, which made oil-gas and condensed it into a liquid. This liquid Faraday examined in 1824, and he found the most important constituent of it to be a light volatile oil, which he called bicarburet of hydrogen. The gas company, I presume, came to an end; but what of the volatile liquid? Obtained from coal-tar, and renamed Benzine or Benzol, it is now prepared on a large scale, and used as a solvent in some of our industrial arts. But other chemists have worked upon it, and torturing it with nitric acid, they have produced nitrobenzol—a gift to the confectioner and the perfumer. And by attacking this with reducing agents there was called into existence the wondrous base aniline,—wondrous indeed when we consider the transformations it underwent in the hands of Hofmann, and the light it was made to throw on the internal structure of organic compounds. Faraday used sometimes to pay a visit to the Royal College of Chemistry, and revel in watching these marvellous reactions. But aniline was of use to others besides the theoretical chemist. Tortured by fresh appliances, this base gave highly-coloured bodies which it was found possible to fix on cotton as well as woollen and silken fabrics, and thence sprang up a large and novel branch of industry, while our eyes were delighted with the rich hues of mauve and magenta, the Bleu de Paris, and various other "aniline dyes."
Everyone who is at all acquainted with the habits of electricity knows that the most impassable of obstacles is the air, while iron bolts and bars only help it in its flight: yet, if an electrified body be brought near another body, with this invisible barrier between them, the electrical state of the second body is disturbed. Faraday thought much over this question of "induction," as it is called, and found himself greatly puzzled to comprehend how a body should act where it is not. At length he satisfied himself by experiment that the interposed obstacle is itself affected by the electricity, and acquires an electro-polar state by which it modifies electric action in its neighbourhood. The amount varies with the nature of the substance, and Faraday estimated it for such dielectrics as sulphur, shellac, or spermaceti, compared with air. He termed this new property of matter "specific inductive capacity," and figured in his own mind the play of the molecules as they propagated and for a while retained the force. Now, these very recondite observations were opposed to the philosophy of the day, and they were not received by some of the leading electricians, especially of the Continent, while those who first tried to extend his experiments blundered over the matter. However, the present Professor Sir William Thomson, then a student at Cambridge, showed that while Faraday's views were rigorously deducible from Coulomb's theory, this discovery was a great advance in the philosophy of the subject. When submarine telegraph wires had to be manufactured, Thomson took "specific inductive capacity" into account in determining the dimensions of the cable: for we have there all the necessary conditions—the copper wire is charged with electricity, the covering of gutta-percha is a "dielectric," and the water outside is ready to have an opposite electric condition induced in it. The result is that, as Faraday himself predicted, the message is somewhat retarded; and of course it becomes a thing of importance so to arrange matters that this retardation may be as small as possible, and the signals may follow one another speedily. Now this must depend not only on the thickness of the covering, but also on the nature of the substance employed, and it was likely enough that gutta-percha was not the best possible substance. In fact, when Professor Fleeming Jenkin came to try the inductive capacity of gutta-percha by means of the Red Sea cable, he found it to be almost double that of shellac, which was the highest that Faraday had determined, and attempts have been made since to obtain some substance which should have less of this objectionable quality and be as well adapted otherwise for coating a wire. There is Hooper's material, the great merit of which is its low specific inductive capacity, so that it permits of the sending of four signals while gutta-percha will only allow three to pass along; and Mr. Willoughby Smith has made an improved kind of gutta-percha with reduced capacity. Of course no opinion is expressed here on the value of these inventions, as many other circumstances must be taken into account, such as their durability and their power of insulation,—that is, preventing the leakage of the galvanic charge; but at least they show that one of the most abstruse discoveries of Faraday has penetrated already into our patent offices and manufactories. Two students in the Physical Laboratory at Glasgow have lately determined with great care the inductive capacity of paraffin, and there can be little doubt that the speculations of the philosopher as to the condition of a dielectric will result in rendering it still more easy than at present to send words of information or of friendly greeting to our cousins across the Atlantic or the Indian Ocean.
The history of the magneto-electric light affords another remarkable instance of the way in which one of Faraday's most recondite discoveries bore fruit in his own lifetime; and it is the more interesting as it fell to his own lot to assist in bringing the fruit to maturity.
"Brighton, November 29, 1831.
"Dear Phillips,
"For once in my life I am able to sit down and write to you without feeling that my time is so little that my letter must of necessity be a short one; and accordingly I have taken an extra large sheet of paper, intending to fill it with news.
"But how are you getting on? Are you comfortable? And how does Mrs. Phillips do; and the girls? Bad correspondent as I am, I think you owe me a letter; and as in the course of half an hour you will be doubly in my debt, pray write us, and let us know all about you. Mrs. Faraday wishes me not to forget to put her kind remembrances to you and Mrs. Phillips in my letter....
"We are here to refresh. I have been working and writing a paper that always knocks me up in health; but now I feel well again, and able to pursue my subject; and now I will tell you what it is about. The title will be, I think, 'Experimental Researches in Electricity:'—I. On the Induction of Electric Currents; II. On the Evolution of Electricity from Magnetism; III. On a new Electrical Condition of Matter; IV. On Arago's Magnetic Phenomena. There is a bill of fare for you; and, what is more, I hope it will not disappoint you. Now, the pith of all this I must give you very briefly; the demonstrations you shall have in the paper when printed...."
So wrote Faraday to his intimate friend Richard Phillips, on November 29th, 1831, and the letter goes on to describe the great harvest of results which he had gathered since the 29th of August, when he first obtained evidence of an electric current from a magnet. A few days afterwards he was at work again on these curious relations of magnetism and electricity in his laboratory, and at the Round Pond in Kensington Gardens, and with Father Thames at Waterloo Bridge. On the 8th of February he entered in his note-book: "This evening, at Woolwich, experimented with magnet, and for the first time got the magnetic spark myself. Connected ends of a helix into two general ends, and then crossed the wires in such a way that a blow at a b would open them a little. Then bringing a b against the poles of a magnet, the ends were disjoined, and bright sparks resulted."