220 STUDIES IN ELECTRO-PHYSIOLOGY: 



apparatus. The transmitting wires terminated in two 

 vibrating metal plates, contained in another enclosed box 

 with a camera front, and these plates, by an ingenious 

 method of lighting, allowed a changing band of light, as 

 thin as a hair, to pass between them. This was broken 

 up in turn by two' other vibrating mirrors and projected 

 upon a ground-glass plate, upon which the transmitted 

 image appeared. 



The inventor solved the problem of the conveyance of 

 colour by passing the rays of light received by the lens in 

 the transmitter and from the vibrating metal plates of the 

 receiver through a prism, each ray being deflected more or 

 less and each having an individual deflection ; a violet ray 

 being deflected more than a yellow ray, and a red ray less 

 than a green one, and so on. 



With the technical details of the Telestroscope we need 

 have no further concern. Its interest, to me, lies not in 

 the mechanical details they were necessitated by the fact 

 of there being only one selenium disc in the transmitting 

 apparatus but in certain curious points of resemblance 

 to the human eye. 



If, instead of one transmitting disc and two connecting 

 wires, an infinite number of such discs and wires could have 

 been employed, there would have been no occasion for the 

 vibrating mirrors, for the reason that the " points " 

 projected separately from the object would be received 

 upon a large number of discs and conveyed to the brain 

 by a large number of wires or nerve-fibres. The number 

 of fibres in the optic nerve is said to be upwards of 500,000, 

 while the number of cones in the rod and cone layer of the 

 eye of man the nerve- epithelium of the retina has been 

 estimated at 3,000,000. 



It does not follow that these discs and wires are as 

 multitudinous as the points of light which in their entirety 

 form a % picture or an image. It is because they are not so, 



