By MONS. SENLECQ, of Ardres.

This apparatus, which is intended to transmit to a distance through a telegraphic wire pictures taken on the plate of a camera, was invented in the early part of 1877 by M. Senlecq, of Ardres. A description of the first specification submitted by M. Senlecq to M. du Moncel, member of the Paris Academy of Sciences, appeared in all the continental and American scientific journals. Since then the apparatus has everywhere occupied the attention of prominent electricians, who have striven to improve on it. Among these we may mention MM. Ayrton, Perry, Sawyer (of New York), Sargent (of Philadelphia), Brown (of London), Carey (of Boston), Tighe (of Pittsburg), and Graham Bell himself. Some experimenters have used many wires, bound together cable-wise, others one wire only. The result has been, on the one hand, confusion of conductors beyond a certain distance, with the absolute impossibility of obtaining perfect insulation; and, on the other hand, an utter want of synchronism. The unequal and slow sensitiveness of the selenium likewise obstructed the proper working of the apparatus. Now, without a relative simplicity in the arrangement of the conducting wires intended to convey to a distance the electric current with its variations of intensity, without a perfect and rapid synchronism acting concurrently with the luminous impressions, so as to insure the simultaneous action of transmitter and receiver, without, in fine, an increased sensitiveness in the selenium, the idea of the telectroscope could not be realized. M. Senlecq has fortunately surmounted most of these main obstacles, and we give to-day a description of the latest apparatus he has contrived.

Transmitter

A brass plate, A, whereon the rays of light impinge inside a camera, in their various forms and colors, from the external objects placed before the lens, the said plate being coated with selenium on the side intended to face the dark portion of the camera This brass plate has its entire surface perforated with small holes as near to one another as practicable. These holes are filled with selenium, heated, and then cooled very slowly, so as to obtain the maximum sensitiveness. A small brass wire passes through the selenium in each hole, without, however, touching the plate, on to the rectangular and vertical ebonite plate, B, Fig. 1, from under this plate at point, C. Thus, every wire passing through plate, A, has its point of contact above the plate, B, lengthwise. With this view the wires are clustered together when leaving the camera, and thence stretch to their corresponding points of contact on plate, B, along line, C C. The surface of brass, A, is in permanent contact with the positive pole of the battery (selenium). On each side of plate, B, are let in two brass rails, D and E, whereon the slide hereinafter described works.

Transmitter 275 8a

Fig. 1

Rail, E, communicates with the line wire intended to conduct the various light and shade vibrations. Rail, D, is connected with the battery wire. Along F are a number of points of contact corresponding with those along C C. These contacts help to work the apparatus, and to insure the perfect isochronism of the transmitter and receiver. These points of contact, though insulated one from the other on the surface of the plate, are all connected underneath with a wire coming from the positive pole of a special battery. This apparatus requires two batteries, as, in fact, do all autographic telegraphs--one for sending the current through the selenium, and one for working the receiver, etc. The different features of this important plate may, therefore, be summed up thus:

FIGURE 1.

D. Brass rail, grooved and connected with the line wire working the receiver.

F. Contacts connected underneath with a wire permanently connected with battery.

C. Contacts connected to insulated wires from selenium.

E. Brass rail, grooved, etc., like D.