Some Curiosities. 173 



ha> the power to produce sound or sympathetic 

 vibration in certain substances. 



Another curious application of the sele- 

 nium cell has been attempted, but has scarcely 

 gone beyond the domain of theory. This 

 apparatus, if perfected, might be called a 

 Tdephote. It is an apparatus by which an 

 illuminated picture at one end of a line of 

 many wires is reproduced upon a screen at 

 the other end. The light is not actually trans- 

 mitted, but only its effects. Suppose a picture 

 is laid off into small squares and there is a 

 selenium cell corresponding to each square 

 and for each selenium cell there is a wire that 

 runs to a distant station in which circuit there 

 is a battery. At the distant station there are 

 little shutters, one for each wire, that are con- 

 trolled by the electric current and so adjusted 

 that when the cell at the transmitting-end is 

 in the dark the shutter will be closed. Now if 

 ng light he thrown' upon the picture at 

 the transmit tinir-cnd, and each square of the 

 picture reflects the light upon its correspond- 

 ing selenium cell, the high lights of the 

 picture will reflect stronger light than the 

 shadows, and therefore the wires correspond- 

 to the high-light squares will have a 

 stronger current !' electricity flowing through 

 them, because the resistance of the circuit is 

 less than the ones connected with the darker 

 shadows. So that the degree of current- 



