In another arrangement M. Courtot’s mirror telephone has been employed, and a sort of spring pedal is inserted in the wood of the mouthpiece, which terminates in a bent silver wire, supporting an index adapted to make a contact with a square plate soldered to the diaphragm. The battery is placed in connection with the spring of the pedal, and one end of the telephone coil-wire communicates as before with the diaphragm. When a call is to be made, the pedal must be pressed, and the battery immediately communicates with the silver wire which, with the diaphragm, constitutes the vibrator, and an electric vibration is sent through the circuit, and produces the call. For receiving, the pedal is allowed to revert to its normal position, and the index of the pedal, touching the contact in connection with the diaphragm, establishes direct communication between the two telephones, while breaking the contact of the silver wire with the diaphragm, so that the battery cannot act. It appears that experiments made at the musketry school at Orleans for a distance of 370 miles have been very successful. _M. Varey’s Microphone Speaker._--M. Varey has recently arranged a successful microphonic speaker, in which the principle of the microphone represented in fig. 39 is maintained. The system of three vertical carbons is arranged inside a sort of snuff-box, of which the lid is made of a thin plate of mica, horn, or ebonite. The snuff-box is provided with two hinged arms, so that it may be placed in the most convenient position for speaking, and at the same time the sensitiveness of the instrument can be regulated. A small battery, consisting of two Gaiffe cells of chloride of silver, is placed in the pedestal on which the instrument stands, and sets the microphone at work without further trouble. In this way the speaker can be used like an ordinary telephone, and is not affected by vibrations of air. Only vibrations of sound react upon it. _Microphonic Speaker by Fitch._--Mr. Pope states that this speaker has produced excellent results in America. It is merely Edison’s carbon telephone reduced to its simplest form. It consists of a small cylindrical box, which has a mouthpiece like the one represented fig. 28. The box contains two carbon disks of the same diameter as itself, and is lined with a kind of felt. Metal wires, inlaid in a groove scooped on the circumference of the carbons, place them in communication with the circuit and battery, and transmission takes place by means of the vibrations of the upper carbon, which is directly influenced by the voice without the intervention of any diaphragm. These vibrations, which can be freely developed in consequence of the elasticity of the felt pad which supports the lower carbon, produce on the surface of contact of the two carbons the modifications of intensity of current necessary for the reproduction of speech, in the same way as other microphones.