|A devoted electrician, Varley studied telegraphy after leaving school
and then worked for 18 years for the Electric and International Co. until
the telegraphs were acquired by the Government in 1868. Retiring to a
private life, he focused his energies on making electrical inventions,
including a precursor of the telephone.
Of Varley's capacities as an electrical engineer Thomson was in no
doubt. In a letter to the Secretary of the Atlantic Telegraph Co. of 24
September 1858, when Varley had reported on the fault in the Atlantic
cable and Thomson was still hopeful that the cable could be saved, he
wrote that "Varley's report is, in my opinion, evidence of high scientific
and practical talent". Thomson nominated him for membership of the
Electrical Standards Committee of the British Association - others were
Clerk Maxwell and Joule - which in 1864 determined the standard of
resistance, the ‘B.A. unit’ or ‘ohmad’, since shortened to ‘ohm’.
To the work on the Atlantic cable Varley made a highly important
contribution, first in finding a method of localising faults in submarine
cables, and then in devising an ‘artificial cable’, making it possible to
study in the laboratory the way cables would react in working conditions.
He also invented the use of the signalling condenser to sharpen electric
pulses transmitted through a cable, so increasing the speed of working.
The Atlantic cable and other telegraphic work, including protracted
negotiations over fees and patent rights, form the basis of the
correspondence between Varley and Thomson in the Kelvin Papers, which
consists of some forty letters written between 1859 and 1869.