Obituary of Latimer Clark

MR. LATIMER CLARK, F.R.S.

ON Sunday, October 30, Mr. Latimer Clark, F.R.S., died very suddenly at his residence at Kensington, in his seventy-sixth year. His loss will be keenly felt by the various learned societies of which he was a member ; especially by the Institution of Electrical Engineers, who claimed him as a founder and past-president. The name of Latimer Clark is familiar to all who during the past half-century have watched the various phases of progress in the science and practice of electrical engineering. Submarine cable engineers associate it with inventions that relate to every branch of their profession, from the process of sheathing the "core," to the last refinements of testing; and the constructors of land-lines still recognise the "Latimer Clark" double-bell insulator as a type universally accepted. His book, written in conjunction with the late Robert Sabine, on "Electrical Tables and Formulae," is to be found in every electrician's library, and in every cable-factory and telegraph testing-station in the world ; his "approximate method" of fault-testing on submarine cables, by applying two successive potential differences, was an important step in the development of the modern empirical but nevertheless remarkably exact system of testing by two applications of different battery power ; and his test of the electrical condition of "joints" in cable core is, under the name of "the accumulation method," still in daily use at cable works and on board ship. Another of his valuable contributions to telegraph progress is his study of the errors due to the inductive action of a galvanometer-needle upon its own coil when using shunts of different values, in a series of comparative "discharges." To this must be added his important modification of Poggendorff's method of comparing electro-motive forces, and the introduction, with this test, of the well-known potentiometer that bears his name. This instrument is perhaps associated in our minds rather with the laboratory than with the cable-testing room; and, moreover, it is here in the physical laboratory that we discover what is undoubtedly the best-known of Mr. Latimer Clark's inventions: the zinc-mercury standard cell. The vast amount of work that has been clone, the modifications suggested, and the pages written in regard to this small apparatus, might well lead the uninitiated to suppose that it contains some potent talia azman to which electricians are for ever looking for revelation and mysteries. It happens to be merely the electricians' practical standard of potential-difference: but to those who care to study such things, it is still full of the mystery of the origin and meaning of contact electro-motive force.

The written and legendary history of the early days of electric telegraphs, over land and under sea, shows how closely Mr. Latimer Clark was associated with this work, both at home and abroad. Success did not always reward the efforts of the telegraph engineer, even in those times ; for although commercial competition did not then exist to its present extent, there were all the difficulties of inexperience to be fought against. Success as regards the technical details of construction and working, came sooner than financial success. Estimating the cost of land-lines was beset with the almost insurmountable difficulties of transport and commissariat in countries savage and unexplored. Mr. Latimer Clark, in those pioneer days, was one upon whom the brunt of these reverses at first fell somewhat heavily. All honour to him and to his comrades; they fought for the greatest achievement in the world's history.