Strictly speaking, the telephone is merely an instrument adapted for the transmission of sound to a distance, and this idea of transmitting sound is as old as the world itself. The Greeks made use of means which might effect it, and there is no doubt that these means were sometimes used for the pagan oracles. But such transmission of sound was within somewhat narrow limits, and certainly did not exceed those of a speaking-tube. Mr. Preece considers that the earliest document in which this transmission of sound to a distance is distinctly formulated, dates from 1667: he refers to a paper by one Robert Hooke, who writes to this effect: ‘It is not impossible to hear a whisper at a furlong’s distance, it having been already done; and perhaps the nature of the thing would not make it more impossible, though that furlong should be ten times multiply’d. And though some famous authors have affirm’d it impossible to hear through the thinnest plate of Muscovy glass; yet I know a way, by which ’tis easie enough to hear one speak through a wall a yard thick. It has not yet been thoroughly examin’d how far otacousticons may be improv’d, nor what other wayes there may be of quickning our hearing, or conveying sound through other bodies than the air; for that is not the only medium I can assure the reader, that I have, by the help of a distended wire, propagated the sound to a very considerable distance in an instant, or with as seemingly quick a motion as that of light, at least incomparably quicker than that which at the same time was propagated through the air; and this not only in a straight line or direct, but in one bended in many angles.’ This plan for the transmission of sound is the principle of the string telephones which have attracted attention for some years, and it remained in the stage of simple experiment until 1819, when Sir Charles Wheatstone applied it to his magic lyre. In this instrument, sounds were transmitted through a long strip of deal, with one end in connection with a sounding board: one step more led to the use of the membrane employed in string telephones. It would be difficult to say with whom this idea originated, since it is claimed, as if beyond dispute, by several telephone-makers. If we may believe some travellers, it has long been used in Spain for the correspondence of lovers. However this may be, it was not to be found among the scientific appliances of some years ago, and it was even supposed by many persons that the cord consisted of an acoustic tube of slender diameter. Although the instrument has become a child’s toy, it has great scientific importance, for it proves that vibrations capable of reproducing speech may be extremely minute, since they can be mechanically transmitted more than a hundred yards.