Fig. 43 B.
Fig. 44.
§ 51. In the "Electric Trumpet," introduced by Messrs. Binswanger, of the General Electric Company, we have a very novel and effective arrangement of
the parts of an electric bell and telephone together. This instrument, along with its battery, line and push, is illustrated at [Fig. 44], where A is a hollow brass cylinder, in which is placed an ordinary electro-magnet similar to [Figs. 20] or [20 A]. At the front end, near B, is affixed by its edges a thin disc of sheet iron, precisely as in the Bell telephone,[14] and over against it, at B, is an insulated contact screw, as in the ordinary trembling bell. On the disc of sheet iron, at the spot where the screw touches, is soldered a speck of platinum. The wires from the electro-magnet are connected, one to the upper binding screw, the other to the brass case of the instrument itself, which is in metallic communication
with the sheet iron disc. The return wire from the contact screw is shown attached to the insulated piece, and is fastened to another binding screw (not visible) on the base board. When contact is made with the battery, through the press or push, the magnet becomes energised, and pulls the iron disc or diaphragm towards it, causing it to buckle inwards. In doing this, contact is broken with the screw B; consequently the diaphragm again straightens out, as the magnet no longer pulls it. Again contact is made; when of course the same round of performances is continuously repeated. As the plate or diaphragm vibrates many hundreds of times per second, it sets up a distinctly musical and loud sound wave, not unlike the note of a cornet-a-piston, or a loud harmonium reed. With a number of these "trumpets," each diaphragm being duly tuned to its proper pitch, it would be possible to construct a novel musical instrument, working solely by electricity. The "pushes" need only take the form of pianoforte keys to render the instrument within the grasp of any pianoforte or organ player.