'In 1861, he showed that the electrical resistance of molten alloys is equal to the sum of the resistances of the separate metals, and that latent heat increases the specific resistance of metals in a greater degree than free heat.' In 1864 he made researches on the heating of the sides of a Leyden jar by the electrical discharge. In 1866 he published the general theory of dynamo-electric machines, and the principle of accumulating the magnetic effect, a principle which, however, had been contemporaneously discovered by Mr. S. A. Varley, and described in a patent some years before by Mr. Soren Hjorth, a Danish inventor. Hjorth's patent is to be found in the British Patent Office Library, and until lately it was thought that he was the first and true inventor of the 'dynamo' proper, but we understand there is a prior inventor still, though we have not seen the evidence in support of the statement.

The reversibility of the dynamo was enunciated by Werner Siemens in 1867; but it was not experimentally demonstrated on any practical scale until 1870, when M. Hippolite Fontaine succeeded in pumping water at the Vienna international exhibition by the aid of two dynamos connected in circuit; one, the generator, deriving motion from a hydraulic engine, and in turn setting in motion the receiving dynamo which worked the pump. Professor Clerk Maxwell thought this discovery the greatest of the century; and the remark has been repeated more than once. But it is a remark which derives its chief importance from the man who made it, and its credentials from the paradoxical surprise it causes. The discovery in question is certainly fraught with very great consequences to the mechanical world; but in itself it is no discovery of importance, and naturally follows from Faraday's far greater and more original discovery of magneto-electric generation.

In 1874, Dr. Siemens published a treatise on the laying and testing of submarine cables. In 1875, 1876 and 1877, he investigated the action of light on crystalline selenium, and in 1878 he studied the action of the telephone.

The recent work of Dr. Siemens has been to improve the pneumatic railway, railway signalling, electric lamps, dynamos, electro-plating and electric railways. The electric railway at Berlin in 1880, and Paris in 1881, was the beginning of electric locomotion, a subject of great importance and destined in all probability, to very wide extension in the immediate future. Dr. Siemens has received many honours from learned societies at home and abroad; and a title equivalent to knighthood from the German Government.



VI. LATIMER CLARK.

MR. Clark was born at Great Marlow in 1822, and probably acquired his scientific bent while engaged at a manufacturing chemist's business in Dublin. On the outbreak of the railway mania in 1845 he took to surveying, and through his brother, Mr. Edwin Clark, became assistant engineer to the late Robert Stephenson on the Britannia Bridge. While thus employed, he made the acquaintance of Mr. Ricardo, founder of the Electric Telegraph Company, and joined that Company as an engineer in 1850. He rose to be chief engineer in 1854, and held the post till 1861, when he entered into a partnership with Mr. Charles T. Bright. Prior to this, he had made several original researches; in 1853, he found that the retardation of current on insulated wires was independent of the strength of current, and his experiments formed the subject of a Friday evening lecture by Faraday at the Royal Institution—a sufficient mark of their importance.

In 1854 he introduced the pneumatic dispatch into London, and, in 1856, he patented his well-known double-cup insulator. In 1858, he and Mr. Bright produced the material known as 'Clark's Compound,' which is so valuable for protecting submarine cables from rusting in the sea-water. In 1859, Mr. Clark was appointed engineer to the Atlantic Telegraph Company which tried to lay an Anglo-American cable in 1865. in partnership with Sir C. T. Bright, who had taken part in the first Atlantic cable expedition, Mr. Clark laid a cable for the Indian Government in the Red Sea, in order to establish a telegraph to India. In 1886, the partnership ceased; but, in 1869, Mr Clark went out to the Persian Gulf to lay a second cable there. Here he was nearly lost in the shipwreck of the Carnatic on the Island of Shadwan in the Red Sea.

Subsequently Mr. Clark became the head of a firm of consulting electricians, well known under the title of Clark, Forde and Company, and latterly including the late Mr. C. Hockin and Mr. Herbert Taylor.

The Mediterranean cable to India, the East Indian Archipelago cable to Australia, the Brazilian Atlantic cables were all laid under the supervision of this firm. Mr. Clark is now in partnership with Mr. Stanfield, and is the joint-inventor of Clark and Stanfield's circular floating dock. He is also head of the well-known firm of electrical manufacturers, Messrs. Latimer Clark, Muirhead and Co., of Regency Street, Westminster.

The foregoing sketch is but an imperfect outline of a very successful life. 'But enough has been given to show that we have here an engineer of various and even brilliant gifts. Mr. Clark has applied himself in divers directions, and never applied himself in vain. There is always some practical result to show which will be useful to others. In technical literature he published a description of the Conway and Britannia Tubular Bridges as long ago as 1849. There is a valuable communication of his in the Board of Trade Blue Rook on Submarine Cables. In 1868, he issued a useful work on ELECTRICAL MEASUREMENTS, and in 1871 joined with Mr. Robert Sabine in producing the well-known ELECTRICAL TABLES AND FORMULAE, a work which was for a long time the electrician's VADE-MECUM. In 1873, he communicated a lengthy paper on the NEW STANDARD OF ELECTROMOTIVE POWER now known as CLARK'S STANDARD CELL; and quite recently he published a treatise on the USE OF THE TRANSIT INSTRUMENT.

Mr. Clark is a Fellow of the Royal Society of London, as well as a member of the Institution of Civil Engineers, the Royal Astronomical Society, the Physical Society, etc., and was elected fourth President of the Society of Telegraph Engineers and of Electricians, now the Institution of Electrical Engineers.

He is a great lover of books and gardening—two antithetical hobbies—which are charming in themselves, and healthily counteractive. The rich and splendid library of electrical works which he is forming, has been munificently presented to the Institution of Electrical Engineers.



VII. COUNT DU MONCEL.

Theodose-Achille-Louis, Comte du Moncel, was born at Paris on March 6, 1821. His father was a peer of France, one of the old nobility, and a General of Engineers. He possessed a model farm near Cherbourg, and had set his heart on training his son to carry on this pet project; but young Du Moncel, under the combined influence of a desire for travel, a love of archaeology, and a rare talent for drawing, went off to Greece, and filled his portfolio with views of the Parthenon and many other pictures of that classic region. His father avenged himself by declining to send him any money; but the artist sold his sketches and relied solely on his pencil. On returning to Paris he supported himself by his art, but at the same time gratified his taste for science in a discursive manner. A beautiful and accomplished lady of the Court, Mademoiselle Camille Clementine Adelaide Bachasson de Montalivet, belonging to a noble and distinguished family, had plighted her troth with him, and, as we have been told, descended one day from her carriage, and wedded the man of her heart, in the humble room of a flat not far from the Grand Opera House. They were a devoted pair, and Madame du Moncel played the double part of a faithful help-meet, and inspiring genius. Heart and soul she encouraged her husband to distinguish himself by his talents and energy, and even assisted him in his labours.

About 1852 he began to occupy himself almost exclusively with electrical science. His most conspicuous discovery is that pressure diminishes the resistance of contact between two conductors, a fact which Clerac in 1866 utilised in the construction of a variable resistance from carbon, such as plumbage, by compressing it with an adjustable screw. It is also the foundation of the carbon transmitter of Edison, and the more delicate microphone of Professor Hughes. But Du Moncel is best known as an author and journalist. His 'Expose des applications de l'electricite' published in 1856 ET SEQ., and his 'Traite pratique de Telegraphie,' not to mention his later books on recent marvels, such as the telephone, microphone, phonograph, and electric light, are standard works of reference. In the compilation of these his admirable wife assisted him as a literary amanuensis, for she had acquired a considerable knowledge of electricity.

In 1866 he was created an officer of the Legion of Honour, and he became a member of numerous learned societies. For some time he was an adviser of the French telegraph administration, but resigned the post in 1873. The following year he was elected a Member of the Academy of Sciences, Paris. In 1879, he became editor of a new electrical journal established at Paris under the title of 'La Lumiere Electrique,' and held the position until his death, which happened at Paris after a few days' illness on February 16, 1884. His devoted wife was recovering from a long illness which had caused her affectionate husband much anxiety, and probably affected his health. She did not long survive him, but died on February 4, 1887, at Mentone in her fifty-fifth year. Count du Moncel was an indefatigable worker, who, instead of abandoning himself to idleness and pleasure like many of his order, believed it his duty to be active and useful in his own day, as his ancestors had been in the past.



VIII. ELISHA GRAY.

THIS distinguished American electrician was born at Barnesville in Belmont county, Ohio, on August 2, 1835. His family were Quakers, and in early life he was apprenticed to a carpenter, but showed a taste for chemistry, and at the age of twenty-one he went to Oberlin College, where he studied for five years. At the age of thirty he turned his attention to electricity, and invented a relay which adapted itself to the varying insulation of the telegraph line. He was then led to devise several forms of automatic repeaters, but they are not much employed. In 1870-2, he brought out a needle annunciator for hotels, and another for elevators, which had a large sale. His 'Private Telegraph Line Printer' was also a success. From 1873-5 he was engaged in perfecting his 'Electro-harmonic telegraph.' His speaking telegraph was likewise the outcome of these researches. The 'Telautograph,' or telegraph which writes the messages as a fac-simile of the sender's penmanship by an ingenious application of intermittent currents, is the latest of his more important works. Mr. Gray is a member of the firm of Messrs. Gray and Barton, and electrician to the Western Electric Manufacturing Company of Chicago. His home is at Highland Park near that city.

THE END