Page:Heroes of the telegraph (IA cu31924031222494).djvu/90



Till now the enterprise had been purely American, and the funds provided by American capitalists, with the exception of a few shares held by Mr. J. W. Brett. But seeing that the cable was to land on British soil, it was fitting that the work should be international, and that the British people should be asked to contribute towards the manufacture and submersion of the cable. Mr. Field therefore proceeded to London, and with the assistance of Mr. Brett the Atlantic Telegraph Company was floated. Mr. Field himself supplied a quarter of the needed capital; and we may add that Lady Byron, and Mr. Thackeray, the novelist, were among the shareholders.

The design of the cable was a subject of experiment by Professor Morse and others. It was known that the conductor should be of copper, possessing a high conductivity for the electric current, and that its insulating jacket of gutta-percha should offer a great resistance to the leakage of the current. Moreover, experience had shown that the protecting sheath or armour of the core should be light and flexible as well as strong, in order to resist external violence and allow it to be lifted for repair. There was another consideration, however, which at this time was rather a puzzle. As early as 1823 Mr. (afterwards Sir) Francis Ronalds had observed that electric signals were retarded in passing through an insulated wire or core laid under ground, and the same effect was noticeable on cores immersed in water, and particularly on the lengthy cable between England and the Hague. Faraday showed that it was caused by induction between the electricity in the wire and the earth or water surrounding it. A core, in fact, is an attenuated Leyden jar; the wire of the core, its insulating jacket, and the soil or water around it stand respectively for the inner tinfoil, the glass, and the outer tinfoil of the jar.