Page:Popular Science Monthly Volume 23.djvu/561

Rh regulator, or loose-contact mechanism, consisting of the spring g bearing on the lever c d, actuated by the elastic membrane o.

The receiver in this figure consists of an electro-magnet, m, on a sounding-board, with an armature, regulated by an adjustable spring, g, pendulum-mounted, and "connected with a lever, i, which is as long as possible, but light and broad." This expansion of the armature is for the purpose of increasing its superficial contact with the air for the propagation of sound-waves. The Reis armature, so equipped, is the equivalent of the "diaphragm" in what is commonly called "the Bell receiver," a form, however, which appears to have originated with Elisha Gray. In the "Bell receiver" the diaphragm is an elastic, expanded, circular armature. The Reis electro-magnetic receiver is thus a complete and perfect anticipation of that of Yeates, of Dublin, in 1865, and of the later receiver of Gray or Bell. The function of all is to move an elastically supported armature backward and forward, and so throw it into vibrations corresponding to those imparted by the sound-waves to the transmitting apparatus.

Fig. 2 is copied from the "Prospectus" of Reis, dated August, 1863, containing instructions to accompany the telephones constructed for him, and sold by W. Albert, of Frankfort. The transmitter here shown has been usually called the "box-instrument." In this type, instead of a spring adjustment of the current-regulator or loose-contact mechanism, as in Fig. 1, we have the angle-shaped "Hammerchen," as Reis called it, or little hammer, poised on the supports a b,



and resting by gravity on the strip of platinum-foil at the center of the tympanum seen below. A little drop of mercury at b makes perfect electric communication between the little hammer and neighboring screw-cup. The elastic feature of this loose-contact arrangement is confined to the animal or other membrane of the tympanum itself.