"The telectroscope"
The Times, 27 January 1879
Cet article est le second article connu paraissant en anglais - mais le premier en Grande-Bretagne - sur le projet de télectroscope de Senlecq. Il constitue une traduction de l'article paru dans Les Mondes, édité par l'Abbé Moigno, du 16 janvier 1879. Il est donc beaucoup plus détaillé que le simple entrefilet, paru dans Nature, le 23 janvier de la même année. Il atteste du retentissement international immédiat de la proposition du notaire d'Ardres.
M. Senlecq, of Ardres, has recently submitted to the examination of MM. du Moncel and Hallez d'Arros, a plan of an apparatus intended to reproduce telegraphically at a distance the image obtained in the camera oscura. This apparatus will be based on the property posseded by selenium of offering a variable and very sensitive electrical resistance according to the different graduations of light. The apparatus will consist of an ordinary camera oscura containing at the focus an unpolished glass and any system of autographic telegraphic transmission ; the tracing point of the transmitter intended to traverse the surface of the unpolished glass will be formed of a small piece of selenium held by two springs acting as pincers, insulated and connected, one with a pile, the other with the line. The point of selenium will form the circuit. In gliding over the surface, more or less lightened up, of the unpolished glass, this point will communicate, in different degree and with great sensitiveness the vibrations of the light. The receiver will also be a tracing point of blackhead or pencil for drawing very fixely, connected with a very thin plate of soft iron, held almost as in the Bell telephone, and vibrating before an electro-magnet, governed by the irregular current emitted in the line. This pencil, supporting a sheet of paper arranged so as to receive the impression of the image produced in the camera oscura, will translate the vibration of the metallic plate by a more or less pronounced pressure on that sheet of paper. Should the selenium tracing point run over a light surface the current will increase is intensity, the electro-magnet of the receiver will attract to it with greater force the vibrating plate, and the pencil will exert less pressure on the paper. The line thus formed will be scarcely, if at all, visible ; the contrary will be the case if the surface be obscure, for the resistance of the current increasing, the attraction of the magnet will diminish, and the pencil, pressing more on the paper, will have upon it a darker line. M. Senlecq thinks he will succeed in amplifying this apparatus by suppressing the electro-magnet and collecting directly on the paper by means of a particular composition the different graduations of tints proportional to the intensity of the electric current.