The experiments on the microphone made in London at the meeting of the Society of Telegraphic Engineers on May 25, 1878, were wonderfully successful, and they were the subject of an interesting article in the ‘Engineer’ of May 31, which asserts that the whole assembly heard the microphone speak, and that its voice was very like that of the phonograph. When the meeting was informed that these words had been uttered at some distance from the microphone, the Duke of Argyll, who was present, while admiring the important discovery, could not help exclaiming that this invention might have terrible consequences, since, for instance, if one of Professor Hughes’s instruments were placed in the room in Downing Street, in which Her Majesty’s ministers hold their cabinet council, their secrets might be heard in the room in which the present meeting took place. He added that if one of these little instruments were in the pocket of Count Schouvaloff, or of Lord Salisbury, we should at once be in possession of the secrets for which all Europe was anxiously waiting. If these instruments were able to repeat all the conversations held in the room in which they stood, they might be really dangerous, and the Duke thought that Professor Hughes, who had invented such a splendid yet perilous instrument, ought next to seek an antidote for his discovery. Dr. Lyon Playfair, again, thought that the microphone ought to be applied to the aërophone, so that by placing these instruments in the two Houses of Parliament, the speeches of great orators might be heard by the whole population within five or six square miles. The experiments lately made with the microphone at Halifax show that the Duke of Argyll’s predictions were fully justified. It seems that a microphone was placed on a pulpit-desk in a church in Halifax, and connected by a wire about two miles long with a telephone placed close to the bed of a sick person, who was able to hear the prayers, the chanting, and the sermon. This fact was communicated to me by Mr. Hughes, who heard it from a trustworthy source, and it is said that seven patients have subscribed for the expense of an arrangement by which they may hear the church services at Halifax without fatigue. The microphone has also lately been applied to the transmission of a whole opera, as we learn from the following account in the ‘Journal Télégraphique,’ Berne, July 25, 1878:--