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 Institute, 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 class. 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 classics, in music, and in general literature; but the real love, the central passion 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 homogeneous solid bodies, and its connection with the mathematical theory of electricity.' In this he demonstrated the identity 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 class 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 shore. Mr. Brett watched the operations through a glass 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 shore 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 passage 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 shells 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 assured 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 assistance 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 retarded in passing 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 glass, 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 retardation, 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 retardation 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. Glass, Elliot & Co., of Greenwich, and Messrs. R. S. Newall & Co., of Liverpool.

The British Government promised Mr. Field a subsidy of L1,400 a year, and the loan of ships to lay the cable. He solicited an equal help from Congress, but a large number of the senators, actuated by a national jealousy of England, and looking to the fact that both ends of the line were to lie in British territory, opposed the grant. It appeared to these far-sighted politicians that England, the hereditary foe, was 'literally crawling under the sea to get some advantage over the United States.' The Bill was only passed by a majority of a single vote. In the House of Representatives it encountered a similar hostility, but was ultimately signed by President Pierce.

The Agamemnon, a British man-of-war fitted out for the purpose, took in the section made at Greenwich, and the Niagara, an American warship, that made at Liverpool. The vessels and their consorts met in the bay of Valentia Island, on the south-west coast of Ireland, where on August 5, 1857, the shore end of the cable was landed from the Niagara. It was a memorable scene. The ships in the bay were dressed in bunting, and the Lord Lieutenant of Ireland stood on the beach, attended by his following, to receive the end from the American sailors. Visitors in holiday attire collected in groups to watch the operations, and eagerly joined with his excellency in helping to pull the wire ashore. When it was landed, the Reverend Mr. Day, of Kenmore, offered up a prayer, asking the Almighty to prosper the undertaking, Next day the expedition sailed; but ere the Niagara had proceeded five miles on her way the shore-end parted, and the repairing of it delayed the start for another day.

At first the Niagara went slowly ahead to avoid a mishap, but as the cable ran out easily she increased her speed. The night fell, but hardly a soul slept. The utmost vigilance was maintained throughout the vessel. Apart from the noise of the paying-out machinery, there was an awful stillness on board. Men walked about with a muffled step, or spoke in whispers, as if they were afraid the sound of their voices would break the slender line. It seemed as though a great and valued friend lay at the point of death.

The submarine hill, with its dangerous slope, was passed in safety, and the 'telegraph plateau,' nearly two miles deep, was reached, when suddenly the signals from Ireland, which told that the conductor was intact, stopped altogether. Professor Morse and De Sauty, the electricians, failed to restore the communication, and the engineers were preparing to cut the cable, when quite as suddenly the signals returned, and every face grew bright. A weather-beaten old sailor said, 'I have watched nearly every mile of it as it came over the side, and I would have given fifty dollars, poor man as I am, to have saved it, although I don't expect to make anything by it when it is laid down.'

But the joy was short-lived. The line was running out at the rate of six miles an hour, while the vessel was only making four. To check this waste of cable the engineer tightened the brakes; but as the stern of the ship rose on the swell, the cable parted under the heavy strain, and the end was lost in the sea.

The bad news ran like a flash of lightning through all the ships, and produced a feeling of sorrow and dismay.

No attempt was made to grapple the line in such deep water, and the expedition returned to England. It was too late to try again that year, but the following summer the Agamemnon and Niagara, after an experimental trip to the Bay of Biscay, sailed from Plymouth on June 10 with a full supply of cable, better gear than before, and a riper experience of the work. They were to meet in the middle of the Atlantic, where the two halves of the cable on board of each were to be spliced together, and while the Agamemnon payed out eastwards to Valentia Island the Niagara was to pay out westward to Newfoundland. On her way to the rendezvous the Agamemnon encountered a terrific gale, which lasted for a week, and nearly proved her destruction.

On Saturday, the 26th, the middle splice was effected and the bight dropped into the deep. The two ships got under weigh, but had not proceeded three miles when the cable broke in the paying-out machinery of the Niagara. Another splice, followed by a fresh start, was made during the same afternoon; but when some fifty miles were payed out of each vessel, the current which kept up communication between them suddenly failed owing to the cable having snapped in the sea. Once more the middle splice was made and lowered, and the ships parted company a third time. For a day or two all went well; over two hundred miles of cable ran smoothly out of each vessel, and the anxious chiefs began to indulge in hopes of ultimate success, when the cable broke about twenty feet behind the stern of the Agamemnon.

The expedition returned to Queenstown, and a consultation took place. Mr. Field, and Professor Thomson, who was on board the Agamemnon, were in favour of another trial, and it was decided to make one without delay. The vessels left the Cove of Cork on July 17; but on this occasion there was no public enthusiasm, and even those on board felt as if they were going on another wild goose chase. The Agamemnon was now almost becalmed on her way to the rendezvous; but the middle splice was finished by 12.30 p.m. on July 29, 1858, and immediately dropped into the sea. The ships thereupon started, and increased their distance, while the cable ran easily out of them. Some alarm was caused by the stoppage of the continuity signals, but after a time they reappeared. The Niagara deviated from the great arc of a circle on which the cable was to be laid, and the error was traced to the iron of the cable influencing her compass. Hence the Gorgon, one of her consorts, was ordered to go ahead and lead the way. The Niagara passed several icebergs, but none injured the cable, and on August 4 she arrived in Trinity Bay, Newfoundland. At 6. a.m. next morning the shore end was landed into the telegraph-house which had been built for its reception. Captain Hudson, of the Niagara, then read prayers, and at one p.m. H.M.S. Gorgon fired a salute of twenty-one guns.

The Agamemnon made an equally successful run. About six o'clock on the first evening a huge whale was seen approaching on the starboard bow, and as he sported in the waves, rolling and lashing them into foam, the onlookers began to fear that he might endanger the line. Their excitement became intense as the monster heaved astern, nearer and nearer to the cable, until his body grazed it where it sank into the water; but happily no harm was done. Damaged portions of the cable had to be removed in paying-out, and the stoppage of the continuity signals raised other alarms on board. Strong head winds kept the Agamemnon back, and two American ships which got into her course had to be warned off by firing guns. The signals from the Niagara became very weak, but on Professor Thomson asking the electricians on board of her to increase their battery power, they improved at once. At length, on Thursday, August, 5, the Agamemnon, with her consort, the Valorous, arrived at Valentia Island, and the shore end was landed into the cable-house at Knightstown by 3 p.m., and a royal salute announced the completion of the work.

The news was received at first with some incredulity, but on being confirmed it caused a universal joy. On August 16 Queen Victoria sent a telegram of congratulation to President Buchanan through the line, and expressed a hope that it would prove 'an additional link between the nations whose friendship is founded on their common interest and reciprocal esteem.' The President responded that, 'it is a triumph more glorious, because far more useful to mankind, than was ever won by conqueror on the field of battle. May the Atlantic telegraph, under the blessing of heaven, prove to be a bond of perpetual peace and friendship between the kindred nations, and an instrument destined by Divine Providence to diffuse religion, civilisation, liberty, and law throughout the world.'

These messages were the signal for a fresh outburst of enthusiasm. Next morning a grand salute of 100 guns resounded in New York, the streets were decorated with flags, the bells of the churches rung, and at night the city was illuminated.

The Atlantic cable was a theme of inspiration for innumerable sermons and a prodigious quantity of doggerel. Among the happier lines were these:—

The rejoicing reached a climax in September, when a public service was held in Trinity Church, and Mr. Field, the hero of the hour, as head and mainspring of the expedition, received an ovation in the Crystal Palace at New York. The mayor presented him with a golden casket as a souvenir of 'the grandest enterprise of our day and generation.' The band played 'God save the Queen,' and the whole audience rose to their feet. In the evening there was a magnificent torchlight procession of the city firemen.

That very day the cable breathed its last. Its insulation had been failing for some days, and the only signals which could be read were those given by the mirror galvanometer.[It is said to have broken down while Newfoundland was vainly attempting to inform Valentia that it was sending with THREE HUNDRED AND TWELVE CELLS!] The reaction at this news was tremendous. Some writers even hinted that the line was a mere hoax, and others pronounced it a stock exchange speculation. Sensible men doubted whether the cable had ever 'spoken;' but in addition to the royal despatch, items of daily news had passed through the wire; for instance, the announcement of a collision between two ships, the Arabia and the Europa, off Cape Race, Newfoundland, and an order from London, countermanding the departure of a regiment in Canada for the seat of the Indian Mutiny, which had come to an end.

Mr. Field was by no means daunted at the failure. He was even more eager to renew the work, since he had come so near to success. But the public had lost confidence in the scheme, and all his efforts to revive the company were futile. It was not until 1864 that with the assistance of Mr. Thomas (afterwards Lord) Brassey, and Mr. (now Sir) John Fender, that he succeeded in raising the necessary capital. The Glass, Elliot, and Gutta-Percha Companies were united to form the well-known Telegraph Construction and Maintenance Company, which undertook to manufacture and lay the new cable.

Much experience had been gained in the meanwhile. Long cables had been submerged in the Mediterranean and the Red Sea. The Board of Trade in 1859 had appointed a committee of experts, including Professor Wheatstone, to investigate the whole subject, and the results were published in a Blue-book. Profiting by these aids, an improved type of cable was designed. The core consisted of a strand of seven very pure copper wires weighing 300 lbs. a knot, coated with Chatterton's compound, which is impervious to water, then covered with four layers of gutta-percha alternating with four thin layers of the compound cementing the whole, and bringing the weight of the insulator to 400 lbs. per knot. This core was served with hemp saturated in a preservative solution, and on the hemp as a padding were spirally wound eighteen single wires of soft steel, each covered with fine strands of Manilla yam steeped in the preservative. The weight of the new cable was 35.75 cwt. per knot, or nearly twice the weight of the old, and it was stronger in proportion.

Ten years before, Mr. Marc Isambard Brunel, the architect of the Great Eastern, had taken Mr. Field to Blackwall, where the leviathan was lying, and said to him, 'There is the ship to lay the Atlantic cable.' She was now purchased to fulfil the mission. Her immense hull was fitted with three iron tanks for the reception of 2,300 miles of cable, and her decks furnished with the paying-out gear. Captain (now Sir) James Anderson, of the Cunard steamer China, a thorough seaman, was appointed to the command, with Captain Moriarty, R.N., as chief navigating officer. Mr. (afterwards Sir) Samuel Canning was engineer for the contractors, the Telegraph Construction and Maintenance Company, and Mr. de Sauty their electrician; Professor Thomson and Mr. Cromwell Fleetwood Varley were the electricians for the Atlantic Telegraph Company. The Press was ably represented by Dr. W. H. Russell, correspondent of the TIMES. The Great Eastern took on board seven or eight thousand tons of coal to feed her fires, a prodigious quantity of stores, and a multitude of live stock which turned her decks into a farmyard. Her crew all told numbered 500 men.

At noon on Saturday, July 15, 1865, the Great Eastern left the Nore for Foilhommerum Bay, Valentia Island, where the shore end was laid by the Caroline.

At 5.30 p.m. on Sunday, July 23, amidst the firing of cannon and the cheers of the telegraph fleet, she started on her voyage at a speed of about four knots an hour. The weather was fine, and all went well until next morning early, when the boom of a gun signalled that a fault had broken out in the cable. It turned out that a splinter of iron wire had penetrated the core. More faults of the kind were discovered, and as they always happened in the same watch, there was a suspicion of foul play. In repairing one of these on July 31, after 1,062 miles had been payed out, the cable snapped near the stern of the ship, and the end was lost. 'All is over,' quietly observed Mr. Canning; and though spirited attempts were made to grapple the sunken line in two miles of water, they failed to recover it.

The Great Eastern steamed back to England, where the indomitable Mr. Field issued another prospectus, and formed the Anglo-American Telegraph Company, with a capital of L600,000, to lay a new cable and complete the broken one. On July 7, 1866, the William Cory laid the shore end at Valentia, and on Friday, July 13, about 3 p.m., the Great Eastern started paying-out once more. [Friday is regarded as an unlucky, and Sunday as a lucky day by sailors. The Great Eastern started on Sunday before and failed; she succeeded now. Columbus sailed on a Friday, and discovered America on a Friday.] A private service of prayer was held at Valentia by invitation of two directors of the company, but otherwise there was no celebration of the event. Professor Thomson was on board; but Dr. W. H. Russell had gone to the seat of the Austro-Prussian war, from which telegrams were received through the cable.

The 'big ship' was attended by three consorts, the Terrible, to act as a spy on the starboard how, and warn other vessels off the course, the Medway on the port, and the Albany on the starboard quarter, to drop or pick up buoys, and make themselves generally useful. Despite the fickleness of the weather, and a 'foul flake,' or clogging of the line as it ran out of the tank, there was no interruption of the work. The 'old coffee mill,' as the sailors dubbed the paying-out gear, kept grinding away. 'I believe we shall do it this time, Jack,' said one of the crew to his mate.

On the evening of Friday, July 27, the expedition made the entrance of Trinity Bay, Newfoundland, in a thick fog, and next morning the Great Eastern cast her anchor at Heart's Content. Flags were flying from the little church and the telegraph station on shore. The Great Eastern was dressed, three cheers were given, and a salute was fired. At 9 a.m. a message from England cited these words from a leading article in the current TIMES: 'It is a great work, a glory to our age and nation, and the men who have achieved it deserve to be honoured among the benefactors of their race.' 'Treaty of peace signed between Prussia and Austria.' The shore end was landed during the day by the Medway; and Captain Anderson, with the officers of the telegraph fleet, went in a body to the church to return thanks for the success of the expedition. Congratulations poured in, and friendly telegrams were again exchanged between Her Majesty and the United States. The great work had been finally accomplished, and the two worlds were lastingly united.

On August 9 the Great Eastern put to sea again in order to grapple the lost cable of 1865, and complete it to Newfoundland. Arriving in mid-ocean she proceeded to fish for the submerged line in two thousand fathoms of water, and after repeated failures, involving thirty casts of the grapnel, she hooked and raised it to surface, then spliced it to the fresh cable in her hold, and payed out to Heart's Content, where she arrived on Saturday, September 7. There were now two fibres of intelligence between the two hemispheres.

On his return home, Professor Thomson was among those who received the honour of knighthood for their services in connection with the enterprise. He deserved it. By his theory and apparatus he probably did more than any other man, with the exception of Mr. Field, to further the Atlantic telegraph. We owe it to his admirable inventions, the mirror instrument of 1857 and the siphon recorder of 1869, that messages through long cables are so cheap and fast, and, as a consequence, that ocean telegraphy is now so common. Hence some account of these two instruments will not be out of place.

Sir William Thomson's siphon recorder, in all its present completeness, must take rank as a masterpiece of invention. As used in the recording or writing in permanent characters of the messages sent through long submarine cables, it is the acknowledged chief of 'receiving instruments,' as those apparatus are called which interpret the electrical condition of the telegraph wire into intelligible signals. Like other mechanical creations, no doubt its growth in idea and translation into material fact was a step-by-step process of evolution, culminating at last in its great fitness and beauty.

The marvellous development of telegraphy within the last generation has called into existence a great variety of receiving instruments, each admirable in its way. The Hughes, or the Stock Exchange instruments, for instance, print the message in Roman characters; the sounders strike it out on stops or bells of different tone; the needle instruments indicate it by oscillations of their needles; the Morse daubs it in ink on paper, or embosses it by a hard style; while Bain's electro-chemical receiver stains it on chemically prepared paper. The Meyer-Baudot and the Quadruple receive four messages at once and record them separately; while the harmonic telegraph of Elisha Gray can receive as many as eight simultaneously, by means of notes excited by the current in eight separate tuning forks.

But all these instruments have one great drawback for delicate work, and, however suitable they may be for land lines, they are next to useless for long cables. They require a certain definite strength of current to work them, whatever it may be, and in general it is very considerable. Most of the moving parts of the mechanism are comparatively heavy, and unless the current is of the proper strength to move them, the instrument is dumb, while in Bain's the solution requires a certain power of current to decompose it and leave the stain.

In overland lines the current traverses the wire suddenly, like a bullet, and at its full strength, so that if the current be sufficiently strong these instruments will be worked at once, and no time will be lost. But it is quite different on submarine cables. There the current is slow and varying. It travels along the copper wire in the form of a wave or undulation, and is received feebly at first, then gradually rising to its maximum strength, and finally dying away again as slowly as it rose. In the French Atlantic cable no current can be detected by the most delicate galvanoscope at America for the first tenth of a second after it has been put on at Brest; and it takes about half a second for the received current to reach its maximum value. This is owing to the phenomenon of induction, very important in submarine cables, but almost entirely absent in land lines. In submarine cables, as is well known, the copper wire which conveys the current is insulated from the sea-water by an envelope, usually of gutta-percha. Now the electricity sent into this wire INDUCES electricity of an opposite kind to itself in the sea-water outside, and the attraction set up between these two kinds 'holds back' the current in the wire, and retards its passage to the receiving station.

It follows, that with a receiving instrument set to indicate a particular strength of current, the rate of signalling would be very slow on long cables compared to land lines; and that a different form of instrument is required for cable work. This fact stood greatly in the way of early cable enterprise. Sir William (then Professor) Thomson first solved the difficulty by his invention of the 'mirror galvanometer,' and rendered at the same time the first Atlantic cable company a commercial success. The merit of this receiving instrument is, that it indicates with extreme sensibility all the variations of the current in the cable, so that, instead of having to wait until each signal wave sent into the cable has travelled to the receiving end before sending another, a series of waves may be sent after each other in rapid succession. These waves, encroaching upon each other, will coalesce at their bases; but if the crests remain separate, the delicate decipherer at the other end will take cognisance of them and make them known to the eye as the distinct signals of the message.

The mirror galvanometer is at once beautifully simple and exquisitely scientific. It consists of a very long fine coil of silk-covered copper wire, and in the heart of the coil, within a little air-chamber, a small round mirror, having four tiny magnets cemented to its back, is hung, by a single fibre of floss silk no thicker than a spider's line. The mirror is of film glass silvered, the magnets of hair-spring, and both together sometimes weigh only one-tenth of a grain. A beam of light is thrown from a lamp upon the mirror, and reflected by it upon a white screen or scale a few feet distant, where it forms a bright spot of light.

When there is no current on the instrument, the spot of light remains stationary at the zero position on the screen; but the instant a current traverses the long wire of the coil, the suspended magnets twist themselves horizontally out of their former position, the mirror is of course inclined with them, and the beam of light is deflected along the screen to one side or the other, according to the nature of the current. If a POSITIVE current—that is to say, a current from the copper pole of the battery—gives a deflection to the RIGHT of zero, a NEGATIVE current, or a current from the zinc pole of the battery, will give a deflection to the left of zero, and VICE VERSA.

The air in the little chamber surrounding the mirror is compressed at will, so as to act like a cushion, and 'deaden' the movements of the mirror. The needle is thus prevented from idly swinging about at each deflection, and the separate signals are rendered abrupt and 'dead beat,' as it is called.

At a receiving station the current coming in from the cable has simply to be passed through the coil of the 'speaker' before it is sent into the ground, and the wandering light spot on the screen faithfully represents all its variations to the clerk, who, looking on, interprets these, and cries out the message word by word.

The small weight of the mirror and magnets which form the moving part of this instrument, and the range to which the minute motions of the mirror can be magnified on the screen by the reflected beam of light, which acts as a long impalpable hand or pointer, render the mirror galvanometer marvellously sensitive to the current, especially when compared with other forms of receiving instruments. Messages have been sent from England to America through one Atlantic cable and back again to England through another, and there received on the mirror galvanometer, the electric current used being that from a toy battery made out of a lady's silver thimble, a grain of zinc, and a drop of acidulated water.

The practical advantage of this extreme delicacy is, that the signal waves of the current may follow each other so closely as almost entirely to coalesce, leaving only a very slight rise and fall of their crests, like ripples on the surface of a flowing stream, and yet the light spot will respond to each. The main flow of the current will of course shift the zero of the spot, but over and above this change of place the spot will follow the momentary fluctuations of the current which form the individual signals of the message. What with this shifting of the zero and the very slight rise and fall in the current produced by rapid signalling, the ordinary land line instruments are quite unserviceable for work upon long cables.

The mirror instrument has this drawback, however—it does not 'record' the message. There is a great practical advantage in a receiving instrument which records its messages; errors are avoided and time saved. It was to supply such a desideratum for cable work that Sir William Thomson invented the siphon recorder, his second important contribution to the province of practical telegraphy. He aimed at giving a GRAPHIC representation of the varying strength of the current, just as the mirror galvanometer gives a visual one. The difficulty of producing such a recorder was, as he himself says, due to a difficulty in obtaining marks from a very light body in rapid motion, without impeding that motion. The moving body must be quite free to follow the undulations of the current, and at the same time must record its motions by some indelible mark. As early as 1859, Sir William sent out to the Red Sea cable a piece of apparatus with this intent. The marker consisted of a light platinum wire, constantly emitting sparks from a Rhumkorff coil, so as to perforate a line on a strip of moving paper; and it was so connected to the movable needle of a species of galvanometer as to imitate the motions of the needle. But before it reached the Red Sea the cable had broken down, and the instrument was returned dismantled, to be superseded at length by the siphon recorder, in which the marking point is a fine glass siphon emitting ink, and the moving body a light coil of wire hung between the poles of a magnet.

The principle of the siphon recorder is exactly the inverse of the mirror galvanometer. In the latter we have a small magnet suspended in the centre of a large coil of wire—the wire enclosing the magnet, which is free to rotate round its own axis. In the former we have a small coil suspended between the poles of a large magnet—the magnet enclosing the coil, which is also free to rotate round its own axis. When a current passes through this coil, so suspended in the highly magnetic space between the poles of the magnet, the coil itself experiences a mechanical force, causing it to take up a particular position, which varies with the nature of the current, and the siphon which is attached to it faithfully figures its motion on the running paper.

The point of the siphon does not touch the paper, although it is very close. It would impede the motion of the coil if it did. But the 'capillary attraction' of so fine a tube will not permit the ink to flow freely of itself, so the inventor, true to his instincts, again called in the aid of electricity, and electrified the ink. The siphon and reservoir are together supported by an EBONITE bracket, separate from the rest of the instrument, and INSULATED from it; that is to say, electricity cannot escape from them to the instrument. The ink may, therefore, be electrified to an exalted state, or high POTENTIAL as it is called, while the body of the instrument, including the paper and metal writing-tablet, are in connection with the earth, and at low potential, or none at all, for the potential of the earth is in general taken as zero.

The ink, for example, is like a highly-charged thunder-cloud supported over the earth's surface. Now the tendency of a charged body is to move from a place of higher to a place of lower potential, and consequently the ink tends to flow downwards to the writing-tablet. The only avenue of escape for it is by the fine glass siphon, and through this it rushes accordingly and discharges itself in a rain upon the paper. The natural repulsion between its like electrified particles causes the shower to issue in spray. As the paper moves over the pulleys a delicate hair line is marked, straight when the siphon is stationary, but curved when the siphon is pulled from side to side by the oscillations of the signal coil.

It is to the mouse-mill that me must look both for the electricity which is used to electrify the ink and for the motive power which drives the paper. This unique and interesting little motor owes its somewhat epigrammatic title to the resemblance of the drum to one of those sparred wheels turned by white mice, and to the amusing fact of its capacity for performing work having been originally computed in terms of a 'mouse-power.' The mill is turned by a stream of electricity flowing from the battery above described, and is, in fact, an electro-magnetic engine worked by the current.

The alphabet of signals employed is the 'Morse code,' so generally in vogue throughout the world. In the Morse code the letters of the alphabet are represented by combinations of two distinct elementary signals, technically called 'dots' and 'dashes,' from the fact that the Morse recorder actually marks the message in long and short lines, or dots and dashes. In the siphon recorder script dots and dashes are represented by curves of opposite flexure. The condensers are merely used to sharpen the action of the current, and render the signals more concise and distinct on long cables. On short cables, say under three hundred miles long, they are rarely, if ever, used.

The speed of signalling by the siphon recorder is of course regulated by the length of cable through which it is worked. The instrument itself is capable of a wide range of speed. The best operators cannot send over thirty-five words per minute by hand, but a hundred and twenty words or more per minute can be transmitted by an automatic sender, and the recorder has been found on land lines and short cables to write off the message at this incredible speed. When we consider that every word is, on the average, composed of fifteen separate waves, we may better appreciate the rapidity with which the siphon can move. On an ordinary cable of about a thousand miles long, the working speed is about twenty words per minute. On the French Atlantic it is usually about thirteen, although as many as seventeen have sometimes been sent.

The 'duplex' system, or method of telegraphing in opposite directions at once through the same wire, has of late years been applied, in connection with the recorder, to all the long cables of that most enterprising of telegraph companies—the Eastern—so that both stations may 'speak' to each other simultaneously. Thus the carrying capacity of the wire is in practice nearly doubled, and recorders are busy writing at both ends of the cable at once, as if the messages came up out of the sea itself.

We have thus far followed out the recorder in its practical application to submarine telegraphy. Let us now regard it for a moment in its more philosophic aspect. We are at once struck with its self-dependence as a machine, and even its resemblance in some respects to a living creature. All its activity depends on the galvanic current. From three separate sources invisible currents are led to its principal parts, and are at once physically changed. That entering the mouse-mill becomes transmuted in part into the mechanical motion of the revolving drum, and part into electricity of a more intense nature—into mimic lightning, in fact, with its accompaniments of heat and sound. That entering the signal magnet expends part of its force in the magnetism of the core. That entering the signal coil, which may be taken as the brain of the instrument, appears to us as INTELLIGENCE.

The recorder is now in use in all four quarters of the globe, from Northern Europe to Southern Brazil, from China to New England. Many and complete are the adjustments for rendering it serviceable under a wide range of electrical conditions and climatic changes. The siphon is, of course, in a mechanical sense, the most delicate part, but, in an electrical sense, the mouse-mill proves the most susceptible. It is essential for the fine marking of the siphon that the ink should neither be too strongly nor too feebly electrified. When the atmosphere is moderately humid, a proper supply of electricity is generated by the mouse-mill, the paper is sufficiently moist, and the ink flows freely. But an excess of moisture in the air diminishes the available supply of EXALTED electricity. In fact, the damp depositing on the parts leads the electricity away, and the ink tends to clog in the siphon. On the other hand, drought not only supercharges the ink, but dries the paper so much that it INSULATES the siphon point from the metal tablet and the earth. There is then an insufficient escape for the electricity of the ink to earth; the ink ceases to flow down the siphon; the siphon itself becomes highly electrified and agitated with vibrations of its own; the line becomes spluttered and uncertain.

Various devices are employed at different stations to cure these local complaints. The electrician soon learns to diagnose and prescribe for this, his most valuable charge. At Aden, where they suffer much from humidity, the mouse-mill is or has been surrounded with burning carbon. At Malta a gas flame was used for the same purpose. At Suez, where they suffer from drought, a cloud of steam was kept rising round the instrument, saturating the air and paper. At more temperate places the ordinary means of drying the air by taking advantage of the absorbing power of sulphuric acid for moisture prevailed. At Marseilles the recorder acted in some respects like a barometer. Marseilles is subject to sudden incursions of dry northerly winds, termed the MISTRAL. The recorder never failed to indicate the mistral when it blew, and sometimes even to predict it by many hours. Before the storm was itself felt, the delicate glass pen became agitated and disturbed, the frail blue line broken and irregular. The electrician knew that the mistral would blow before long, and, as it rarely blows for less than three days at a time, that rather rude wind, so dreaded by the Marseillaise, was doubly dreaded by him.

The recorder was first used experimentally at St. Pierre, on the French Atlantic cable, in 1869. This was numbered 0, as we were told by Mr. White of Glasgow, the maker, whose skill has contributed not a little to the success of the recorder. No. 1 was first used practically on the Falmouth and Gibraltar cable of the Eastern Telegraph Company in July, 1870. No. 1 was also exhibited at Mr. (now Sir John) Pender's telegraph soiree in 1870. On that occasion, memorable even beyond telegraphic circles, 'three hundred of the notabilities of rank and fashion gathered together at Mr. Pender's house in Arlington Street, Piccadilly, to celebrate the completion of submarine communication between London and Bombay by the successful laying of the Falmouth, Gibraltar and Malta and the British Indian cable lines.' Mr. Pender's house was literally turned outside in; the front door was removed, the courtyard temporarily covered with an iron roof and the whole decorated in the grandest style. Over the gateway was a gallery filled with the band of the Scots Fusilier Guards; and over the portico of the house door hung the grapnel which brought up the 1865 cable, made resplendent to the eye by a coating of gold leaf. A handsome staircase, newly erected, permitted the guests to pass from the reception-room to the drawing-room. In the grounds at the back of the house stood the royal tent, where the Prince of Wales and a select party, including the Duke of Cambridge and Lady Mayo, wife of the Viceroy of India at that time, were entertained at supper. Into this tent were brought wires from India, America, Egypt, and other places, and Lady Mayo sent off a message to India about half-past eleven, and had received a reply before twelve, telling her that her husband and sons were quite well at five o'clock the next morning. The recorder, which was shown in operation, naturally stood in the place of honour, and attracted great attention.

The minor features of the recorder have been simplified by other inventors of late; for example, magnets of steel have been substituted for the electro-magnets which influence the swinging coil; and the ink, instead of being electrified by the mouse-mill, is shed on the paper by a rapid vibration of the siphon point.

To introduce his apparatus for signalling on long submarine cables, Sir William Thomson entered into a partnership with Mr. C. F. Varley, who first applied condensers to sharpen the signals, and Professor Fleeming Jenkin, of Edinburgh University. In conjunction with the latter, he also devised an 'automatic curb sender,' or key, for sending messages on a cable, as the well-known Wheatstone transmitter sends them on a land line.

In both instruments the signals are sent by means of a perforated ribbon of paper; but the cable sender was the more complicated, because the cable signals are formed by both positive and negative currents, and not merely by a single current, whether positive or negative. Moreover, to curb the prolongation of the signals due to induction, each signal was made by two opposite currents in succession—a positive followed by a negative, or a negative followed by a positive, as the case might be. The after-current had the effect of curbing its precursor. This self-acting cable key was brought out in 1876, and tried on the lines of the Eastern Telegraph Company.

Sir William Thomson took part in the laying of the French Atlantic cable of 1869, and with Professor Jenkin was engineer of the Western and Brazilian and Platino-Brazilian cables. He was present at the laying of the Para to Pernambuco section of the Brazilian coast cables in 1873, and introduced his method of deep-sea sounding, in which a steel pianoforte wire replaces the ordinary land line. The wire glides so easily to the bottom that 'flying soundings' can be taken while the ship is going at full speed. A pressure-gauge to register the depth of the sinker has been added by Sir William.

About the same time he revived the Sumner method of finding a ship's place at sea, and calculated a set of tables for its ready application. His most important aid to the mariner is, however, the adjustable compass, which he brought out soon afterwards. It is a great improvement on the older instrument, being steadier, less hampered by friction, and the deviation due to the ship's own magnetism can be corrected by movable masses of iron at the binnacle.

Sir William is himself a skilful navigator, and delights to cruise in his fine yacht, the Lalla Rookh, among the Western Islands, or up the Mediterranean, or across the Atlantic to Madeira and America. His interest in all things relating to the sea perhaps arose, or at any rate was fostered, by his experiences on the Agamemnon and the Great Eastern. Babbage was among the first to suggest that a lighthouse might be made to signal a distinctive number by occultations of its light; but Sir William pointed out the merits of the Morse telegraphic code for the purpose, and urged that the signals should consist of short and long flashes of the light to represent the dots and dashes.

Sir William has done more than any other electrician to introduce accurate methods and apparatus for measuring electricity. As early as 1845 his mind was attracted to this subject. He pointed out that the experimental results of William Snow Harris were in accordance with the laws of Coulomb.

In the Memoirs of the Roman Academy of Sciences for 1857 he published a description of his new divided ring electrometer, which is based on the old electroscope of Bohnenberger and since then he has introduced a chain or series of beautiful and effective instruments, including the quadrant electrometer, which cover the entire field of electrostatic measurement. His delicate mirror galvanometer has also been the forerunner of a later circle of equally precise apparatus for the measurement of current or dynamic electricity.

To give even a brief account of all his physical researches would require a separate volume; and many of them are too abstruse or mathematical for the general reader. His varied services have been acknowledged by numerous distinctions, including the highest honour a British man of science can obtain—the Presidency of the Royal Society of London, to which he was elected at the end of last year.

Sir William Thomson has been all his life a firm believer in the truth of Christianity, and his great scientific attainments add weight to the following words, spoken by him when in the chair at the annual meeting of the Christian Evidence Society, May 23, 1889:—'I have long felt that there was a general impression in the non-scientific world, that the scientific world believes Science has discovered ways of explaining all the facts of Nature without adopting any definite belief in a Creator. I have never doubted that that impression was utterly groundless. It seems to me that when a scientific man says—as it has been said from time to time—that there is no God, he does not express his own ideas clearly. He is, perhaps, struggling with difficulties; but when he says he does not believe in a creative power, I am convinced he does not faithfully express what is in his own mind, He does not fully express his own ideas. He is out of his depth.

'We are all out of our depth when we approach the subject of life. The scientific man, in looking at a piece of dead matter, thinking over the results of certain combinations which he can impose upon it, is himself a living miracle, proving that there is something beyond that mass of dead matter of which he is thinking. His very thought is in itself a contradiction to the idea that there is nothing in existence but dead matter. Science can do little positively towards the objects of this society. But it can do something, and that something is vital and fundamental. It is to show that what we see in the world of dead matter and of life around us is not a result of the fortuitous concourse of atoms.

'I may refer to that old, but never uninteresting subject of the miracles of geology. Physical science does something for us here. St. Peter speaks of scoffers who said that "all things continue as they were from the beginning of the creation;" but the apostle affirms himself that "all these things shall be dissolved." It seems to me that even physical science absolutely demonstrates the scientific truth of these words. We feel that there is no possibility of things going on for ever as they have done for the last six thousand years. In science, as in morals and politics, there is absolutely no periodicity. One thing we may prophesy of the future for certain—it will be unlike the past. Everything is in a state of evolution and progress. The science of dead matter, which has been the principal subject of my thoughts during my life, is, I may say, strenuous on this point, that THE AGE OF THE EARTH IS DEFINITE. We do not say whether it is twenty million years or more, or less, but me say it is NOT INDEFINITE. And we can say very definitely that it is not an inconceivably great number of millions of years. Here, then, we are brought face to face with the most wonderful of all miracles, the commencement of life on this earth. This earth, certainly a moderate number of millions of years ago, was a red-hot globe; all scientific men of the present day agree that life came upon this earth somehow. If some form or some part of the life at present existing came to this earth, carried on some moss-grown stone perhaps broken away from mountains in other worlds; even if some part of the life had come in that way—for there is nothing too far-fetched in the idea, and probably some such action as that did take place, since meteors do come every day to the earth from other parts of the universe;—still, that does not in the slightest degree diminish the wonder, the tremendous miracle, we have in the commencement of life in this world.'