It is quite intelligible that the effect obtained in this system might be reproduced, if, instead of contact-breakers or electric rheotomes, mechanical contact-breakers were used at the sending station, so arranged as to furnish the requisite number of breaks in the current which communicates the vibrations of the different notes of the scale. In this way also it would be possible to dispense with the induction coil, by causing the current which has been broken by the mechanical contact-breaker to react upon the receiver. Mr. Elisha Gray has moreover made a different arrangement of this telephonic system, which he has applied to telegraphy for simultaneous electric transmissions, of which we shall speak presently. If we may believe Mr. Elisha Gray, the vibrations transmitted by the secondary currents would be capable, by the intervention of the human body, of causing the sounds to be reproduced at a distance by conducting disks, which vibrate readily, and are placed on a sounding-box. In this way musical sounds may be evoked from copper cylinders placed upon a table, from a metallic disk fastened to a kind of violin, from a membrane stretched on a drum, or from any other resonant substance, by touching any of these objects with one hand, while holding the end of the line with the other. These sounds, of which the quality must vary with the substance touched, would reproduce the transmitted note with the precise number of vibrations which belong to it.[1] _Mr. Varley’s Telephone._--This is, strictly speaking, merely a musical telephone of the same kind as that of Mr. Gray, but the arrangement of the receiver is original and interesting. This part of the instrument essentially consists of a drum of large size (three or four feet in diameter), within which is a condenser formed of four sheets of tinfoil, divided by sheets of some insulating material, and with a surface of about half the size of the drum. The plates of the condenser are placed parallel to the membranes of the drum, and very little removed from its surface. If an electric charge is communicated to one of the series of conducting plates of the condenser, those which correspond to it are attracted, and if they were movable they might communicate to the intervening strata of air a movement which, on reaching the membranes of the drum, might, by a series of charges in rapid succession, cause the membranes to vibrate, and thus produce sounds: these sounds would correspond to the number of charges and discharges which had occurred. Since these charges and discharges are determined by the contact of the two plates of the condenser, at the extremities of the secondary circuit of an induction coil, of which the primary circuit has been duly broken, it becomes evident that, in order to cause the drum to emit any given sound, it will be enough to produce the number of vibrations in the contact-breaker of the induction coil which are required for this sound.