Madras Native Infantry, he returned home on furlough, owing to ill-health, and afterwards relinquished this connection. In 1833-4 he studied anatomy and physiology in Paris, acquiring great skill at modelling dissections in coloured wax.
In the summer of 1835, while touring in Switzerland with his parents, he visited Heidelberg, and was induced by Professor Tiedeman, director of the Anatomical Institute, to return there and continue his wax modelling. He lodged at 97, Stöckstrasse, in the house of a brewer, and modelled in a room nearly opposite. Some of his models have been preserved in the Anatomical Museum at Heidelberg. In March 1836, hearing accidentally from Mr. J. W. R. Hoppner, a son of Lord Byron's friend, that the Professor of Natural Philosophy in the University, Geheime Hofrath Möncke had a model of Baron Schilling's telegraph, Cooke went to see it on March 6, in the Professor's lecture room, an upper storey of an old convent of Dominicans, where he also lived. Struck by what he witnessed, he abandoned his medical studies, and resolved to apply all his energies to the introduction of the telegraph. Within three weeks he had made, partly at Heidelberg, and partly at Frankfort, his first galvanometer, or needle telegraph. It consisted of three magnetic needles surrounded by multiplying coils, and actuated by three separate circuits of six wires. The movements of the needles under the action of the currents produced twenty-six different signals corresponding to the letters of the alphabet.
'Whilst completing the model of my original plan,' he wrote to his mother on April 5, 'others on entirely fresh systems suggested themselves, and I have at length succeeded in combining the utile of each, but the mechanism requires a more delicate hand than mine to execute, or rather instruments which I do not possess. These I can readily have made for me in London, and by the aid of a lathe I shall be able to adapt the several parts, which I shall have made by different mechanicians for secrecy's sake. Should I succeed, it may be the means of putting some hundreds of pounds in my pocket. As it is a subject on which I was profoundly ignorant, until my attention was casually attracted to it the other day, I do not know what others may have done in the same way; this can best be learned in London.'
The 'fresh systems' referred to was his 'mechanical' telegraph, consisting of two letter dials, working synchronously,
