‘It is impossible not to admire the daring invention by which we have been able to realise with these simple expedients the complex problem of reproducing by electricity the tones and delicate articulations of voice and speech; and it was necessary, in order to obtain this result, to find out the means of varying the intensity of the current in the same proportion as the inflections of the sound emitted by the voice.’ If we are to believe Mr. Graham Bell, the invention of the telephone was not due to a spontaneous and fortunate conception: it was the result of his long and patient studies in acoustic science, and of the labours of the physicists who preceded him.[2] His father, Mr. Alexander Melville Bell, of Edinburgh, had studied this science deeply, and had even succeeded in representing with great ingenuity the adaptation of the vocal organs for the emission of sound. It was natural that he should instil a taste for his favourite studies into his son’s mind, and they made together numerous researches in order to discover the relations which exist between the different elements of speech in different languages, and the musical relations of vowels. It is true that several of these researches had been made by M. Helmholtz, and under more favourable conditions; but these studies were of great use to Mr. Bell when he was afterwards occupied with the telephone, and Helmholtz’s experiments, which he repeated with one of his friends, Mr. Hellis of London, concerning the artificial reproduction of vowels by means of electric tuning-forks, launched him into the study of the application of electricity to acoustic instruments. He first invented a system of an electric harmonica with a key-board, in which the different sounds of the scale were reproduced by electric diapasons of different forms, adapted to different notes, and which, when set in motion by the successive lowering of the keys, could reproduce sounds corresponding to the notes touched, just as in an ordinary piano. He next, as he tells us, turned his attention to telegraphy, and thought of making the Morse telegraphs audible by causing the electro-magnetic organ to react on sounding contacts. It is true that this result had already been obtained in the sounders used in telegraphy, but he thought that by applying this system to his electric harmonica, and by employing such an intensifying instrument as Helmholtz’s resonator at the receiving station, it would be possible to obtain through a single wire simultaneous transmissions which should be due to the action of the voice. We shall see presently that this idea was realised almost at the same time by several inventors, among others by M. Paul Lacour, of Copenhagen, Mr. Elisha Gray, of Chicago, and Messrs. Edison and Varley.