during May. Bain further accused Wheatstone of
stealing his idea of the electro-magnetic printing telegraph; but
Wheatstone showed that the instrument was only a modification of his own
electro-magnetic telegraph.

In 1843 Wheatstone communicated an important paper to the Royal Society,
entitled 'An Account of Several New Processes for Determining the
Constants of a Voltaic Circuit.' It contained an exposition of the
well-known balance for measuring the electrical resistance of a
conductor, which still goes by the name of Wheatstone's Bridge or
balance, although it was first devised by Mr. S. W. Christie, of the
Royal Military Academy, Woolwich, who published it in the PHILOSOPHICAL
TRANSACTIONS for 1833. The method was neglected until Wheatstone brought
it into notice. His paper abounds with simple and practical formula:
for the calculation of currents and resistances by the law of Ohm. He
introduced a unit of resistance, namely, a foot of copper wire weighing
one hundred grains, and showed how it might be applied to measure the
length of wire by its resistance. He was awarded a medal for his paper
by the Society. The same year he invented an apparatus which enabled the
reading of a thermometer or a barometer to be registered at a distance
by means of an electric contact made by the mercury. A sound telegraph,
in which the signals were given by the strokes of a bell, was also
patented by Cooke and Wheatstone in May of that year.

The introduction of the telegraph had so far advanced that, on September
2, 1845, the Electric Telegraph Company was registered, and Wheatstone,
by his deed of partnership with Cooke, received a sum of L33,000 for the
use of their joint inventions.

From 1836-7 Wheatstone had thought a good deal about submarine
telegraphs, and in 1840 he gave evidence before the Railway Committee of
the House of Commons on the feasibility of the proposed line from Dover
to Calais. He had even designed the machinery for making and laying
the cable. In the autumn of 1844, with the assistance of Mr. J. D.
Llewellyn, he submerged a length of insulated wire in Swansea Bay, and
signalled through it from a boat to the Mumbles Lighthouse. Next year he
suggested the use of gutta-percha for the coating of the intended wire
across the Channel.

Though silent and reserved in public, Wheatstone was a clear and voluble
talker in private, if taken on his favourite studies, and his small
but active person, his plain but