_System of M. Puluj._--There is yet another call system, devised by M. Puluj. It consists of two telephones without mouthpieces, connected together, and with coils placed opposite the branches of two tuning-forks, tuned as nearly as possible to the same tone. A small metal bell is fixed between the opposite faces of the tuning-forks, and a wire stretched near them is provided with a small ball in contact with their branches. When the tuning-fork at the sending station is put in vibration by striking it with an iron hammer covered with skin, the tuning fork at the other station vibrates also, and its ball strikes upon the bell. As soon as the signal is returned by the second station, mouthpieces with iron diaphragms are fastened to the telephones, and the correspondence begins. It seems that, by the use of a resonator, the sound which reaches the receiving station may be so intensified as to become audible in a large hall, and the bell signal may be heard in an adjoining room, even through a closed door. _Mr. Alfred Chiddey’s System._--This arrangement consists of a slender copper tube, eight inches long, and with an orifice of 1/30 of an inch, of which the lower end is soldered to the diaphragm of a telephone. A branch joint, to which an india-rubber tube is fitted, connects it with a gas jet, which is lighted and surrounded with a lamp shade, in such a way as to make it produce, under given conditions, sounds resembling those of the singing flames. A perfectly similar system is arranged at the other end of the line, in such a way that the sounds emitted in each case shall be precisely in unison. If the two systems are so regulated as not to emit sounds in their normal condition, they can be made to sing by causing a tuning-fork in the vicinity of one or the other to vibrate the same note, and then the corresponding flame will begin to sing, producing a vibration in the diaphragm of the telephone with which it is in correspondence, and hence will follow the vibration of the diaphragm of the other telephone, and consequently the vibration of the flame of the calling instrument. In this way the call signal may be made without the intervention of any battery. APPLICATIONS OF THE TELEPHONE.