The earliest practical telephone transmitter consisted of a diaphragm attached to a wire. The end of the wire was dipped into a bowl containing an acid solution and an electrical contact fixed to the bowl. As the voice vibrated the diaphragm so the wire moved. This created a variable resistance in the solution which was registered through the contact. The device was used by Alexander Graham Bell to utter the immortal words ‘Mr Watson, come here I want you’ on 10 March 1876. Bell did not design this contrivance.
Its specification had been deposited in a caveat—‘a description of an invention not yet perfected’—in the Washington Patent Office nearly a month earlier on 14 February 1876 by Elisha Gray, the co-owner and chief scientist of a Chicago telegraphic equipment manufacturing company. That same day, some two hours earlier it would seem, although no record was kept, Bell patented an ‘Improvement in Telegraphy’ using electromagnets and a vibrating diaphragm of a kind he had been experimenting with for many months. For the previous couple of years he had been in competition with Gray, both of them in the footsteps of many others, to produce a device which could increase the capacity of telegraph wires by allowing a multiplicity of signals to be carried simultaneously. It is perhaps no wonder then that that evening at 5 Exeter Place, Boston, when it must have dawned on Bell that Gray’s design might well transmit sound better than his own, he spilt the acid on his clothing. Bell’s patent—US No. 174465—had been allowed but a week. It had been issued a mere three days before. Yet Gray’s machine was clearly superior (and more fully described) than the one Bell had sketched in his deposition. Watson’s was not the only help Bell would need. 1
The line of enquiry which gives rise to the word ‘telephone’ dates from the seventeenth century. Ear trumpets were developed as signalling systems. For example, Samuel Pepys tried a version of this new invention but noted that it ‘was only a great glass bottle broke at the bottom’; nevertheless he put the neck