This description is certainly not full enough to enable us to discern from it the arrangement which would lead to the solution of the problem, and if the vibrations of the disk at the receiving station were to follow from making and breaking the current at the sending-station, under the influence of vibrations caused by the voice, they would only produce musical, and not articulate sounds. Yet the idea was magnificent, as Mr. Preece said, even when he thought it impossible to realise it. Besides, it is easy to see that M. Bourseul himself was not deceived as to the difficulties of the problem, as far as articulate sounds are concerned, for he points out, as we have seen, the difference existing between the simple vibrations which produce musical sounds, and the complex vibrations which cause articulate sounds; but, as he justly said: ‘Reproduce at the one end of the line the vibrations of air caused at the other, and speech will be transmitted, however complex the mechanism may be by which it is effected.’ We shall presently see how the problem was solved, and it is probable that some attempts had already enabled M. Bourseul to anticipate the solution of the question; but there is nothing in his paper to show what were the means he proposed, so that the discovery of the electric transmission of speech cannot reasonably be ascribed to him, and we do not understand why we should be reproached for having at that time failed to appreciate the importance of a discovery which seemed to be then only within the range of fancy. It was not until 1876 that the problem of the electric transmission of speech was finally solved, and the discovery has lately given rise to an interesting controversy as to priority between Mr. Elisha Gray, of Chicago, and Mr. Graham Bell, on which we must say a few words.