HE philosopher or the essayist, writing on hobbies of a high and inspiring nature, has two recent examples at hand to illustrate his theme, viz.: the example of Sir Francis Ronalds and that of J. Latimer Clark. These distinguished men were contemporaries and friends; both long-lived, moderately moneyed, and ardently fond of old electrical books. Ronalds died at the ripe age of eighty-five, on August 8, 1873, at which time Latimer Clark had entered on his fifty-first year, and had already been collecting material for his Library for nearly a quarter of a century. He was well aware at the outset that the Royal Society had a representative collection, and that Ronalds had even a larger number of old and rare volumes on electricity and telegraphy; yet he believed that there were still many treasures on the dust-covered shelves of private collections which awaited only an appraiser and purchaser. The Library, which for years was housed at

Initial, head piece and tail piece from Gilbert's De Magnete, 1600.

Westminster and known to the electrical world as the Latimer Clark Library, shows how well founded was this belief. During the last forty-eight years of his life, Mr. Clark kept a watchful eye on the lists and catalogues of famous booksellers at home and abroad, and many are the anecdotes told of the patience and shrewdness which he displayed in driving a bargain for a coveted volume.

With Mr. Clark, collecting was an occupation, serious no doubt, but one destined for spare moments and vacation months. It afforded him keen pleasure to buy, to index, and to annotate. His was a hobby fraught with pleasure for himself, and fraught for all time with interest and profit for the student of electrical history.

Josiah Latimer Clark was born at Great Marlow, on March 10, 1822. Having supplemented his elementary education by a course in his favorite subject of chemistry, he obtained employment in a technical capacity with a Dublin firm engaged in the chemical industry. In 1847, encouraged by the activity in railway construction then prevalent, he determined to exchange his chemical pursuits for an appointment as surveyor on one of the numerous lines which were projected at the time. With the knowledge and experience acquired in a twelvemonth, he joined his elder brother, Edwin, who was then resident engineer on the construction of the Britannia Tubular Bridge over the Menai Strait. It was during this period that Mr. Clark gave evidence of special aptitude for applying the energy of the electric current to the purposes of life by firing a time-gun at eight o'clock every evening. Such an achievement attracted

the notice of Mr. J. Lewis Ricardo, who offered the Clark brothers the positions of engineer and assistant-engineer, respectively, to the newly formed Electric Telegraph Company, of which he was chairman. This was in 1850; four years later, Mr. Edwin Clark resigned and his younger brother succeeded him as engineer-in-chief, a position which he held

until 1861, at which time he became consulting engineer to the Company. After 1870 his services were no longer required, as the whole telegraph business of the United Kingdom was taken over by the Government and assigned to the General Post Office Department. The twenty years between 1850 and 1870, during which Mr. Clark was connected with the Electric Telegraph Company, formed for that Company a period of continuous expansion and commercial success,

much of which must be attributed to Mr. Clark's personal influence, his inventive genius, and untiring industry.

While in the service of the Electric Telegraph Company, Mr. Clark was led to undertake a series of experiments on the flow of electricity through underground wires. As early as 1816 Ronalds, who is rightly considered the father of the electric telegraph in England, noticed and in 1823 clearly stated, on page 12 of his "Description of an Electric Telegraph," the retardation which an electric signal would undergo in passing through a long conductor; but his little pamphlet, important and suggestive as it was, attracted no attention at the time. In 1838 Faraday, commenting on Wheatstone's experiments on the "velocity of electricity," predicted that a retardation would occur on account of the electrostatic capacity of the circuit. Twelve years later, that is, in 1850, Dr. Werner Siemens, of Berlin, called attention again to this capacity-effect in a paper on testing for faults in telegraph lines, which was read before the Académie des Sciences, of Paris, on April 29 of that year. But it was not, however, until June 20, 1852, that the retardation was experimentally detected, being then observed by Mr. Clark himself on the London, Leeds, and Liverpool telegraph line. The result of the observation was withheld from the public for a time, as the Directors of the Electric Telegraph Company thought that its premature disclosure would affect their interests prejudicially. The first public demonstration was given by Mr. Clark at the Company's Gutta-Percha Works, at Lothbury, on October 4, 1853, in presence of Faraday, Airy, Edwin Clark, and other men

eminent in the scientific world. Some time later, Mr. Clark undertook, at the request of Professors Airy and Melloni, a series of researches on the electric current which showed that, contrary to the belief of the time, the rate of flow of currents through a conductor is independent of the electric pressure used; in other words, that high potential has no advantage over low potential with regard to the velocity of transmission on land lines, or even on submarine cables. Faraday tersely expressed this in a letter which he wrote to Mr. Clark, by saying "that the force of a weak battery passes with equal rapidity along the line as that of a strong battery."

All this seems to have been forgotten in 1858 when batteries of 380 and even 420 Daniell cells were used at Valentia to force signals through the Atlantic cable; and, on these proving unsatisfactory, recourse was had to the excessive penetrative energy of the induction coil, with the result that a cable costing millions did not long withstand the ill-advised treatment to which it was subjected.

In this connection an experimental test, made by Mr. Clark in 1866, is of special interest. Writing from Valentia, on September 12, he says: "With a single galvanic cell composed of a few drops of acid in a silver thimble and a fragment of zinc weighing a grain or two, conversation may easily, though slowly, be carried on through one of the cables (1865, 1866), or through the two joined together at Newfoundland to form a loop; and, although in the latter case the spark, twice traversing the breadth of the Atlantic, has to pass through 3700 miles of cable, its effects at the receiving end

1 Faraday's MS. letter, Latimer Clark Pamphlets, Vol. ii., p. 3.

* Signals were sent in 1866 from Newfoundland to Valentia by means of a cell consisting of a copper gun-cap with a strip of zinc excited by a drop of water.

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