Henry L. Ellsworth, Commissioner of Patents, came up with a beaming countenance, and holding out her hand, said--

'Professor, I have come to congratulate you.'

'Congratulate me!' replied Morse; 'on what?'

'Why,' she exclaimed,' on the pa.s.sage of your Bill by the Senate!'

It had been voted without debate at the very close of the session. Years afterwards Morse declared that this was the turning-point in the history of the telegraph. 'My personal funds,' he wrote,' were reduced to the fraction of a dollar; and had the pa.s.sage of the Bill failed from any cause, there would have been little prospect of another attempt on my part to introduce to the world my new invention.'

Grateful to Miss Ellsworth for bringing the good news, he declared that when the Washington to Baltimore line was complete hers should be the first despatch.

The Government now paid him a salary of 2,500 dollars a month to superintend the laying of the underground line which he had decided upon. Professors Gale and Fisher became his a.s.sistants. Vail was put in charge, and Mr. Ezra Cornell, who founded the Cornell University on the site of the cotton mill where he had worked as a mechanic, and who had invented a machine for laying pipes, was chosen to supervise the running of the line. The conductor was a five-wire cable laid in pipes; but after several miles had been run from Baltimore to the house intended for the relay, the insulation broke down. Cornell, it is stated, injured his machine to furnish an excuse for the stoppage of the work. The leaders consulted in secret, for failure was staring them in the face.

Some 23,000 dollars of the Government grant were spent, and Mr. Smith, who had lost his faith in the undertaking, claimed 4000 of the remaining 7000 dollars under his contract for laying the line. A bitter quarrel arose between him and Morse, which only ended in the grave. He opposed an additional grant from Government, and Morse, in his dejection, proposed to let the patent expire, and if the Government would use his apparatus and remunerate him, he would reward Alfred Vail, while Smith would be deprived of his portion. Happily, it was decided to abandon the subterranean line, and erect the conductor on poles above the ground. A start was made from the Capitol, Washington, on April 1, 1844, and the line was carried to the Mount Clare Depot, Baltimore, on May 23, 1843.

Next morning Miss Ellsworth fulfilled her promise by inditing the first message. She chose the words, 'What hath G.o.d wrought?' and they were transmitted by Morse from the Capitol at 8.45 a.m., and received at Mount Clare by Alfred Vail.

This was the first message of a public character sent by the electric telegraph in the Western World, and it is preserved by the Connecticut Historical Society. The dots and dashes representing the words were not drawn with pen and ink, but embossed on the paper with a metal stylus.

The machine itself was kept in the National Museum at Washington, and on removing it, in 1871, to exhibit it at the Morse Memorial Celebration at New York, a member of the Vail family discovered a folded paper attached to its base. A corner of the writing was torn away before its importance was recognised; but it proved to be a signed statement by Alfred Vail, to the effect that the method of embossing was invented by him in the sixth storey of the NEW YORK OBSERVER office during 1844, prior to the erection of the Washington to Baltimore line, without any hint from Morse. 'I have not a.s.serted publicly my right as first and sole inventor,' he says, 'because I wished to preserve the peaceful unity of the invention, and because I could not, according to my contract with Professor Morse, have got a patent for it.'

The powers of the telegraph having been demonstrated, enthusiasm took the place of apathy, and Morse, who had been neglected before, was in some danger of being over-praised. A political incident spread the fame of the telegraph far and wide. The Democratic Convention, sitting in Baltimore, nominated Mr. James K. Polk as candidate for the Presidency, and Mr. Silas Wright for the Vice-Presidency. Alfred Vail telegraphed the news to Morse in Washington, and he at once told Mr. Wright. The result was that a few minutes later the Convention was dumbfounded to receive a message from Wright declining to be nominated. They would not believe it, and appointed a committee to inquire into the matter; but the telegram was found to be genuine.

On April 1, 1845, the Baltimore to Washington line was formally opened for public business. The tariff adopted by the Postmaster-General was one cent for every four characters, and the receipts of the first four days were a single cent. At the end of a week they had risen to about a dollar.

Morse offered the invention to the Government for 100,000 dollars, but the Postmaster-General declined it on the plea that its working 'had not satisfied him that under any rate of postage that could be adopted its revenues could be made equal to its expenditures.' Thus through the narrow views and purblindness of its official the nation lost an excellent opportunity of keeping the telegraph system in its own hands.

Morse was disappointed at this refusal, but it proved a blessing in disguise. He and his agent, the Hon. Amos Kendall, determined to rely on private enterprise.

A line between New York and Philadelphia was projected, and the apparatus was exhibited in Broadway at a charge of twenty-five cents a head. But the door-money did not pay the expenses. There was an air of poverty about the show. One of the exhibitors slept on a couple of chairs, and the princely founder of Cornell University was grateful to Providence for a shilling picked up on the side-walk, which enabled him to enjoy a hearty breakfast. Sleek men of capital, looking with suspicion on the meagre furniture and miserable apparatus, withheld their patronage; but humbler citizens invested their hard-won earnings, the Magnetic Telegraph Company was incorporated, and the line was built.

The following year, 1846, another line was run from Philadelphia to Baltimore by Mr. Henry O'Reilly, of Rochester, N.Y., an acute pioneer of the telegraph. In the course of ten years the Atlantic States were covered by a straggling web of lines under the control of thirty or forty rival companies working different apparatus, such as that of Morse, Bain, House, and Hughes, but owing to various causes only one or two were paying a dividend. It was a fit moment for amalgamation, and this was accomplished in 1856 by Mr. Hiram Sibley. 'This Western Union,'

says one in speaking of the united corporation, 'seems to me very like collecting all the paupers in the State and arranging them into a union so as to make rich men of them.' But 'Sibley's crazy scheme' proved the salvation of the competing companies. In 1857, after the first stage coach had crossed the plains to California, Mr. Henry O'Reilly proposed to build a line of telegraph, and Mr. Sibley urged the Western Union to undertake it. He encountered a strong opposition. The explorations of Fremont were still fresh in the public mind, and the country was regarded as a howling wilderness. It was objected that no poles could be obtained on the prairies, that the Indians or the buffaloes would destroy the line, and that the traffic would not pay. 'Well, gentlemen,'

said Sibley, 'if you won't join hands with me in the thing, I'll go it alone.' He procured a subsidy from the Government, who realised the value of the line from a national point of view, the money was raised under the auspices of the Western Union, and the route by Omaha, Fort Laramie, and Salt Lake City to San Francisco was fixed upon. The work began on July 4, 1861, and though it was expected to occupy two years, it was completed in four months and eleven days. The traffic soon became lucrative, and the Indians, except in time of war, protected the line out of friendship for Mr. Sibley. A black-tailed buck, the gift of White Cloud, spent its last years in the park of his home at Rochester.

The success of the overland wire induced the Company to embark on a still greater scheme, the project of Mr. Perry MacDonough Collins, for a trunk line between America and Europe by way of British Columbia, Alaska, the Aleutian Islands, and Siberia. A line already existed between European Russia and Irkutsk, in Siberia, and it was to be extended to the mouth of the Amoor, where the American lines were to join it. Two cables, one across Behring Sea and another across the Bay of Anadyr, were to link the two continents.

The expedition started in the summer of 1865 with a fleet of about thirty vessels, carrying telegraph and other stores. In spite of severe hardships, a considerable part of the line had been erected when the successful completion of the trans-Atlantic cable, in 1866, caused the enterprise to be abandoned after an expenditure of 3,000,000 dollars. A trace cut for the line through the forests of British Columbia is still known as the 'telegraph trail.' In spite of this misfortune the Western Union Telegraph Company has continued to flourish. In 1883 its capital amounted to 80,000,000 dollars, and it now possesses a virtual monopoly of telegraphic communication in the United States.

Morse did not limit his connections to land telegraphy. In 1854, when Mr. Cyrus Field brought out the Atlantic Telegraph Company, to lay a cable between Europe and America, he became its electrician, and went to England for the purpose of consulting with the English engineers on the execution of the project. But his instrument was never used on the ocean lines, and, indeed, it was not adapted for them.

During this time Alfred Vail continued to improve the Morse apparatus, until it was past recognition. The porte-rule and type of the transmitter were discarded for a simple 'key' or rocking lever, worked up and down by the hand, so as to make and break the circuit. The clumsy framework of the receiver was reduced to a neat and portable size. The inking pen was replaced by a metal wheel or disc, smeared with ink, and rolling on the paper at every dot or dash. Vail, as we have seen, also invented the plan of embossing the message. But he did still more. When the recording instrument was introduced, it was found that the clerks persisted in 'reading' the signals by the clicking of the marking lever, and not from the paper. Threats of instant dismissal did not stop the practice when n.o.body was looking on. Morse, who regarded the record as the distinctive feature of his invention, was very hostile to the practice; but Nature was too many for him. The mode of interpreting by sound was the easier and more economical of the two; and Vail, with his mechanical instinct, adopted it. He produced an instrument in which there is no paper or marking device, and the message is simply sounded by the lever of the armature striking on its metal stops. At present the Morse recorder is rarely used in comparison with the 'sounder.'

The original telegraph of Morse, exhibited in 1837, has become an archaic form. Apart from the central idea of employing an electro-magnet to signal--an idea applied by Henry in 1832, when Morse had only thought of it--the development of the apparatus is mainly due to Vail. His working devices made it a success, and are in use to-day, while those of Morse are all extinct.

Morse has been highly honoured and rewarded, not only by his countrymen, but by the European powers. The Queen of Spain sent him a Cross of the Order of Isabella, the King of Prussia presented him with a jewelled snuff-box, the Sultan of Turkey decorated him with the Order of Glory, the Emperor of the French admitted him into the Legion of Honour.

Moreover, the ten European powers in special congress awarded him 400,000 francs (some 80,000 dollars), as an expression of their grat.i.tude: honorary banquets were a common thing to the man who had almost starved through his fidelity to an idea.

But beyond his emoluments as a partner in the invention, Alfred Vail had no recompense. Morse, perhaps, was somewhat jealous of acknowledging the services of his 'mechanical a.s.sistant,' as he at one time chose to regard Vail. When personal friends, knowing his services, urged Vail to insist upon their recognition, he replied, 'I am confident that Professor Morse will do me justice.' But even ten years after the death of Vail, on the occasion of a banquet given in his honour by the leading citizens of New York, Morse, alluding to his invention, said: 'In 1835, according to the concurrent testimony of many witnesses, it lisped its first accents, and automatically recorded them a few blocks only distant from the spot from which I now address you. It was a feeble child indeed, ungainly in its dress, stammering in its speech; but it had then all the distinctive features and characteristics of its present manhood.

It found a friend, an efficient friend, in Mr. Alfred Vail, of New Jersey, who, with his father and brother, furnished the means to give the child a decent dress, preparatory to its' visit to the seat of Government.'

When we remember that even by this time Vail had entirely altered the system of signals, and introduced the dot-dash code, we cannot but regard this as a stinted acknowledgment of his colleague's work. But the man who conceives the central idea, and cherishes it, is apt to be n.i.g.g.ardly in allowing merit to the a.s.sistant whose mechanical skill is able to shape and put it in practice; while, on the other hand, the a.s.sistant is sometimes inclined to attach more importance to the working out than it deserves. Alfred Vail cannot be charged with that, however, and it would have been the more graceful on the part of Morse had he avowed his indebtedness to Vail with a greater liberality. Nor would this have detracted from his own merit as the originator and preserver of the idea, without which the improvements of Vail would have had no existence. In the words of the Hon. Amos Kendall, a friend of both: 'If justice be done, the name of Alfred Vail will for ever stand a.s.sociated with that of Samuel F. B. Morse in the history and introduction into public use of the electro-magnetic telegraph.'

Professor Morse spent his declining years at Locust Grove, a charming retreat on the banks of the River Hudson. In private life he was a fine example of the Christian gentleman.

In the summer of 1871, the Telegraphic Brotherhood of the World erected a statue to his honour in the Central Park, New York. Delegates from different parts of America were present at the unveiling; and in the evening there was a reception at the Academy of Music, where the first recording telegraph used on the Washington to Baltimore line was exhibited. The inventor himself appeared, and sent a message at a small table, which was flashed by the connected wires to the remotest parts of the Union, It ran: 'Greeting and thanks to the telegraph fraternity throughout the world. Glory to G.o.d in the highest, on earth peace, goodwill towards men.'

It was deemed fitting that Morse should unveil the statue of Benjamin Franklin, which had been erected in Printing House Square, New York.

When his venerable figure appeared on the platform, and the long white hair was blown about his handsome face by the winter wind, a great cheer went up from the a.s.sembled mult.i.tude. But the day was bitterly cold, and the exposure cost him his life. Some months later, as he lay on his sick bed, he observed to the doctor, 'The best is yet to come.' In tapping his chest one day, the physician said,' This is the way we doctors telegraph, professor,' and Morse replied with a smile, 'Very good--very good.' These were his last words. He died at New York on April 2, 1872, at the age of eighty-one years, and was buried in the Greenwood Cemetery.

CHAPTER IV. SIR WILLIAM THOMSON.

Sir William Thomson, the greatest physicist of the age, and the highest authority on electrical science, theoretical and applied, was born at Belfast on June 25, 1824. His father, Dr. James Thomson, the son of a Scots-Irish farmer, showed a bent for scholarship when a boy, and became a pupil teacher in a small school near Ballynahinch, in County Down.

With his summer earnings he educated himself at Glasgow University during winter. Appointed head master of a school in connection with the Royal Academical Inst.i.tute, he subsequently obtained the professorship of mathematics in that academy. In 1832 he was called to the chair of mathematics in the University of Glasgow, where he achieved a reputation by his text-books on arithmetic and mathematics.

William began his course at the same college in his eleventh year, and was petted by the older students for his extraordinary quickness in solving the problems of his father's cla.s.s. It was quite plain that his genius lay in the direction of mathematics; and on finishing at Glasgow he was sent to the higher mathematical school of St. Peter's College, Cambridge. In 1845 he graduated as second wrangler, but won the Smith prize. This 'consolation stakes' is regarded as a better test of originality than the tripos. The first, or senior, wrangler probably beat him by a facility in applying well-known rules, and a readiness in writing. One of the examiners is said to have declared that he was unworthy to cut Thomson's pencils. It is certain that while the victor has been forgotten, the vanquished has created a world-wide renown.

While at Cambridge he took an active part in the field sports and athletics of the University. He won the Silver Sculls, and rowed in the winning boat of the Oxford and Cambridge race. He also took a lively interest in the cla.s.sics, in music, and in general literature; but the real love, the central pa.s.sion of his intellectual life, was the pursuit of science. The study of mathematics, physics, and in particular, of electricity, had captivated his imagination, and soon engrossed all the teeming faculties of his mind. At the age of seventeen, when ordinary lads are fond of games, and the cleverer sort are content to learn without attempting to originate, young Thomson had begun to make investigations. The CAMBRIDGE MATHEMATICAL JOURNAL of 1842 contains a paper by him--'On the uniform motion of heat in h.o.m.ogeneous solid bodies, and its connection with the mathematical theory of electricity.'

In this he demonstrated the ident.i.ty of the laws governing the distribution of electric or magnetic force in general, with the laws governing the distribution of the lines of the motion of heat in certain special cases. The paper was followed by others on the mathematical theory of electricity; and in 1845 he gave the first mathematical development of Faraday's notion, that electric induction takes place through an intervening medium, or 'dielectric,' and not by some incomprehensible 'action at a distance.' He also devised an hypothesis of electrical images, which became a powerful agent in solving problems of electrostatics, or the science which deals with the forces of electricity at rest.

On gaining a fellowship at his college, he spent some time in the laboratory of the celebrated Regnault, at Paris; but in 1846 he was appointed to the chair of natural philosophy in the University of Glasgow. It was due to the brilliant promise he displayed, as much as to the influence of his father, that at the age of twenty-two he found himself wearing the gown of a learned professor in one of the oldest Universities in the country, and lecturing to the cla.s.s of which he was a freshman but a few years before.

Thomson became a man of public note in connection with the laying of the first Atlantic cable. After Cooke and Wheatstone had introduced their working telegraph in 1839; the idea of a submarine line across the Atlantic Ocean began to dawn on the minds of men as a possible triumph of the future. Morse proclaimed his faith in it as early as the year 1840, and in 1842 he submerged a wire, insulated with tarred hemp and india-rubber, in the water of New York harbour, and telegraphed through it. The following autumn Wheatstone performed a similar experiment in the Bay of Swansea. A good insulator to cover the wire and prevent the electricity from leaking into the water was requisite for the success of a long submarine line. India-rubber had been tried by Jacobi, the Russian electrician, as far back as 1811. He laid a wire insulated with rubber across the Neva at St. Petersburg, and succeeded in firing a mine by an electric spark sent through it; but india-rubber, although it is now used to a considerable extent, was not easy to manipulate in those days. Luckily another gum which could be melted by heat, and readily applied to the wire, made its appearance. Gutta-percha, the adhesive juice of the ISONANDRA GUTTA tree, was introduced to Europe in 1842 by Dr. Montgomerie, a Scotch surveyor in the service of the East India Company. Twenty years before he had seen whips made of it in Singapore, and believed that it would be useful in the fabrication of surgical apparatus. Faraday and Wheatstone soon discovered its merits as an insulator, and in 1845 the latter suggested that it should be employed to cover the wire which it was proposed to lay from Dover to Calais. It was tried on a wire laid across the Rhine between Deutz and Cologne. In 1849 Mr. C. V. Walker, electrician to the South Eastern Railway Company, submerged a wire coated with it, or, as it is technically called, a gutta-percha core, along the coast off Dover.

The following year Mr. John Watkins Brett laid the first line across the Channel. It was simply a copper wire coated with gutta-percha, without any other protection. The core was payed out from a reel mounted behind the funnel of a steam tug, the Goliath, and sunk by means of lead weights attached to it every sixteenth of a mile. She left Dover about ten o'clock on the morning of August 28, 1850, with some thirty men on board and a day's provisions. The route she was to follow was marked by a line of buoys and flags. By eight o'clock in the evening she arrived at Cape Grisnez, and came to anchor near the sh.o.r.e. Mr. Brett watched the operations through a gla.s.s at Dover. 'The declining sun,' he says, 'enabled me to discern the moving shadow of the steamer's smoke on the white cliff; thus indicating her progress. At length the shadow ceased to move. The vessel had evidently come to an anchor. We gave them half an hour to convey the end of the wire to sh.o.r.e and attach the type-printing instrument, and then I sent the first electrical message across the Channel. This was reserved for Louis Napoleon.' According to Mr. F. C. Webb, however, the first of the signals were a mere jumble of letters, which were torn up. He saved a specimen of the slip on which they were printed, and it was afterwards presented to the Duke of Wellington.

Next morning this pioneer line was broken down at a point about 200 Yards from Cape Grisnez, and it turned out that a Boulogne fisherman had raised it on his trawl and cut a piece away, thinking he had found a rare species of tangle with gold in its heart. This misfortune suggested the propriety of arming the core against mechanical injury by sheathing it in a cable of hemp and iron wires. The experiment served to keep alive the concession, and the next year, on November 13, 1851, a protected core or true cable was laid from a Government hulk, the Blazer, which was towed across the Channel.

Next year Great Britain and Ireland were linked together. In May, 1853, England was joined to Holland by a cable across the North Sea, from Orfordness to the Hague. It was laid by the Monarch, a paddle steamer which had been fitted for the work. During the night she met with such heavy weather that the engineer was lashed near the brakes; and the electrician, Mr. Latimer Clark, sent the continuity signals by jerking a needle instrument with a string. These and other efforts in the Mediterranean and elsewhere were the harbingers of the memorable enterprise which bound the Old World and the New.

Bishop Mullock, head of the Roman Catholic Church in Newfoundland, was lying becalmed in his yacht one day in sight of Cape Breton Island, and began to dream of a plan for uniting his savage diocese to the mainland by a line of telegraph through the forest from St. John's to Cape Ray, and cables across the mouth of the St. Lawrence from Cape Ray to Nova Scotia. St. John's was an Atlantic port, and it seemed to him that the pa.s.sage of news between America and Europe could thus be shortened by forty-eight hours. On returning to St. John's he published his idea in the COURIER by a letter dated November 8, 1850.

About the same time a similar plan occurred to Mr. F. N. Gisborne, a telegraph engineer in Nova Scotia. In the spring of 1851 he procured a grant from the Legislature of Newfoundland, resigned his situation in Nova Scotia, and having formed a company, began the construction of the land line. But in 1853 his bills were dishonoured by the company, he was arrested for debt, and stripped of all his fortune. The following year, however, he was introduced to Mr. Cyrus Field, of New York, a wealthy merchant, who had just returned from a six months' tour in South America. Mr. Field invited Mr. Gisborne to his house in order to discuss the project. When his visitor was gone, Mr. Field began to turn over a terrestrial globe which stood in his library, and it flashed upon him that the telegraph to Newfoundland might be extended across the Atlantic Ocean. The idea fired him with enthusiasm. It seemed worthy of a man's ambition, and although he had retired from business to spend his days in peace, he resolved to dedicate his time, his energies, and fortune to the accomplishment of this grand enterprise.

A presentiment of success may have inspired him; but he was ignorant alike of submarine cables and the deep sea. Was it possible to submerge the cable in the Atlantic, and would it be safe at the bottom? Again, would the messages travel through the line fast enough to make it pay!

On the first question he consulted Lieutenant Maury, the great authority on mareography. Maury told him that according to recent soundings by Lieutenant Berryman, of the United States brig Dolphin, the bottom between Ireland and Newfoundland was a plateau covered with microscopic sh.e.l.ls at a depth not over 2000 fathoms, and seemed to have been made for the very purpose of receiving the cable. He left the question of finding a time calm enough, the sea smooth enough, a wire long enough, and a ship big enough,' to lay a line some sixteen hundred miles in length to other minds. As to the line itself, Mr. Field consulted Professor Morse, who a.s.sured him that it was quite possible to make and lay a cable of that length. He at once adopted the scheme of Gisborne as a preliminary step to the vaster undertaking, and promoted the New York, Newfoundland, and London Telegraph Company, to establish a line of telegraph between America and Europe. Professor Morse was appointed electrician to the company.

The first thing to be done was to finish the line between St. John's and Nova Scotia, and in 1855 an attempt was made to lay a cable across the Gulf of the St. Lawrence, It was payed out from a barque in tow of a steamer; but when half was laid a gale rose, and to keep the barque from sinking the line was cut away. Next summer a steamboat was fitted out for the purpose, and the cable was submerged. St. John's was now connected with New York by a thousand miles of land and submarine telegraph.

Mr. Field then directed his efforts to the completion of the trans-oceanic section. He induced the American Government to despatch Lieutenant Berryman, in the Arctic, and the British Admiralty to send Lieutenant: Dayman, in the Cyclops, to make a special survey along the proposed route of the cable. These soundings revealed the existence of a submarine hill dividing the 'telegraph plateau' from the shoal water on the coast of Ireland, but its slope was gradual and easy.

Till now the enterprise had been purely American, and the funds provided by American capitalists, with the exception of a few shares held by Mr.

J. W. Brett. But seeing that the cable was to land on British soil, it was fitting that the work should be international, and that the British people should be asked to contribute towards the manufacture and submersion of the cable. Mr. Field therefore proceeded to London, and with the a.s.sistance of Mr. Brett the Atlantic Telegraph Company was floated. Mr. Field himself supplied a quarter of the needed capital; and we may add that Lady Byron, and Mr. Thackeray, the novelist, were among the shareholders.

The design of the cable was a subject of experiment by Professor Morse and others. It was known that the conductor should be of copper, possessing a high conductivity for the electric current, and that its insulating jacket of gutta-percha should offer a great resistance to the leakage of the current. Moreover, experience had shown that the protecting sheath or armour of the core should be light and flexible as well as strong, in order to resist external violence and allow it to be lifted for repair. There was another consideration, however, which at this time was rather a puzzle. As early as 1823 Mr. (afterwards Sir) Francis Ronalds had observed that electric signals were r.e.t.a.r.ded in pa.s.sing through an insulated wire or core laid under ground, and the same effect was noticeable on cores immersed in water, and particularly on the lengthy cable between England and the Hague. Faraday showed that it was caused by induction between the electricity in the wire and the earth or water surrounding it. A core, in fact, is an attenuated Leyden jar; the wire of the core, its insulating jacket, and the soil or water around it stand respectively for the inner tinfoil, the gla.s.s, and the outer tinfoil of the jar. When the wire is charged from a battery, the electricity induces an opposite charge in the water as it travels along, and as the two charges attract each other, the exciting charge is restrained. The speed of a signal through the conductor of a submarine cable is thus diminished by a drag of its own making. The nature of the phenomenon was clear, but the laws which governed it were still a mystery. It became a serious question whether, on a long cable such as that required for the Atlantic, the signals might not be so sluggish that the work would hardly pay. Faraday had said to Mr. Field that a signal would take 'about a second,' and the American was satisfied; but Professor Thomson enunciated the law of r.e.t.a.r.dation, and cleared up the whole matter. He showed that the velocity of a signal through a given core was inversely proportional to the square of the length of the core. That is to say, in any particular cable the speed of a signal is diminished to one-fourth if the length is doubled, to one-ninth if it is trebled, to one-sixteenth if it is quadrupled, and so on. It was now possible to calculate the time taken by a signal in traversing the proposed Atlantic line to a minute fraction of a second, and to design the proper core for a cable of any given length.

The accuracy of Thomson's law was disputed in 1856 by Dr. Edward O.

Wildman Whitehouse, the electrician of the Atlantic Telegraph Company, who had misinterpreted the results of his own experiments. Thomson disposed of his contention in a letter to the ATHENAEUM, and the directors of the company saw that he was a man to enlist in their adventure. It is not enough to say the young Glasgow professor threw himself heart and soul into their work. He descended in their midst like the very genius of electricity, and helped them out of all their difficulties. In 1857 he published in the ENGINEER the whole theory of the mechanical forces involved in the laying of a submarine cable, and showed that when the line is running out of the ship at a constant speed in a uniform depth of water, it sinks in a slant or straight incline from the point where it enters the water to that where it touches the bottom.

To these gifts of theory, electrical and mechanical, Thomson added a practical boon in the shape of the reflecting galvanometer, or mirror instrument. This measurer of the current was infinitely more sensitive than any which preceded it, and enables the electrician to detect the slightest flaw in the core of a cable during its manufacture and submersion. Moreover, it proved the best apparatus for receiving the messages through a long cable. The Morse and other instruments, however suitable for land lines and short cables, were all but useless on the Atlantic line, owing to the r.e.t.a.r.dation of the signals; but the mirror instrument sprang out of Thomson's study of this phenomenon, and was designed to match it. Hence this instrument, through being the fittest for the purpose, drove the others from the field, and allowed the first Atlantic cables to be worked on a profitable basis.

The cable consisted of a strand of seven copper wires, one weighing 107 pounds a nautical mile or knot, covered with three coats of gutta-percha, weighing 261 pounds a knot, and wound with tarred hemp, over which a sheath of eighteen strands, each of seven iron wires, was laid in a close spiral. It weighed nearly a ton to the mile, was flexible as a rope, and able to withstand a pull of several tons. It was made conjointly by Messrs. Gla.s.s, Elliot & Co., of Greenwich, and Messrs. R. S. Newall & Co., of Liverpool.