(b.) The transmitter, A, is essentially a parallelepipedal body of wood. The upper part, u x, of it is cut out of one piece [of wood] with square cross-section, the side, x x, of which measures 9 centimetres, and its height, u x, 2·8 centimetres.

This part is moveable upon a hinge on the lower little box, A A. If the cover, x u, is laid back, one sees that a small circle of 3·9 centimetres diameter has been cut out in the same. Into this hole passes a brass collar with a flange 8 millimetres broad, which is furnished at one side with a groove like a pulley. Over the collar there is stretched the membrane, m m, by means of a silk thread lying in the shoulder of the same. This circular membrane is surrounded by a wider circular aperture, b b, = 8·5 centimetres. A shovel-shaped little strip of platinum, n s, lies (over it) leading to the brass binding-screw, d, with the circular part, s, falling upon the centre of the membrane.

By means of some sealing-wax this circular part is fastened to the membrane, and thereby compelled to take part in the vibrations of the same. The further transmission of the galvanic current from the centre takes place by means of a platinum or steel point resting in a cup of mercury, which is extended in a screw, which transmits the current farther. The point a serves as a support for the angular hook, a s b, which in general is supported like a tripod, in order that the point of contact, s, may remain as constant as possible. The hook, a s b, is simply struck with a hole at a upon a projecting point, and lies upon a broader under part. From b the galvanic circuit proceeds by means of an overspun wire to the brass key e (A, [Fig. 33]), and from there farther in the direction represented by the arrow.

The lower part A A of the transmitter is put together of thin wood and forms a parallelepiped, whose height = 6·8 cm., and whose width = 7·7 cm. An inclined mouthpiece of tin with funnel-shaped opening serves to receive the tones. The longer side of this mouthpiece measures 6·7 cm., the shorter 4·7 cm.; the longer diameter of the widening measures 7·15 cm., the shorter diameter 7·5 cm., and finally the diameter of the narrow tube 3·9 cm.

It is clear that, if necessary, the platinum strip can be replaced by a strip of thin sheet-brass, the platinum or steel points by iron. Only in this case the points of contact must be oftener cleaned to a metallic polish.

(c.) The receiver (Zeichengeber) C is in general a double resonant box, whose upper part, “the cover,” is moveable upon two hinges, and can be laid back. The length of this cover is 16·4 cm., its width 9·5 cm., and its height 3·2 cm. The length of the lower box measures 22·9 cm., its width 9·6 cm., and its height 2·5 cm. The under part of the resonant box bears two wooden bridges, which stand about 7·4 cm. from each other, and which serves as supports for the 21·5 cm. long, and 0·9 cm. thick iron needle destined for reproducing the tones. The length of spiral wound over the needle, and designed for making an electro-magnet of the same, is 15 cm. The wooden covers of both parts, scraped as thin as possible, and the greatest breadth of the circular holes shown in the figure, measures 13 mm.

(d.) For a battery one can successfully use a small Smee’s consisting of four elements, or two larger Bunsen’s cells.

The conductor must be at least sufficiently long that one cannot perceive the tones that are produced. For correspondence between the two stations the inventor has employed the electro-magnetic telegraph arrangement, e v g h, seen in the mechanism, and easily understood. An agreement in reference to corresponding signs can be easily arranged, and the simplest way is to accept the signals arranged by the inventor. (See ‘Prospectus.’)

The receiver C gives, when the key e is pressed, the corresponding telegraphic signals by means of tones in the rod E E, while at the transmitter, A, the electro-magnet v gives the signals by means of the springy armature z.