ANIMAL AND VEGETABLE 219 



inventions of scientific interest but no great commercial 

 value have resulted. 



One of the most successful attempts the in- 

 vention of a Pole named Szczepanik to transmit pictures 

 to a distance by the agency of selenium was described in 

 Pearson's Magazine of October, 1899, by Mr. Cleveland 

 Moffett. It was called the " T electroscope," and was 

 founded upon the fact that any vision or image produced 

 upon the retina is only the blending together of an infinite 

 number of points projected separately from the object and 

 seen by separate rays of light. Some of these come a 

 fraction of a second later than others, but if the intervals 

 between them be short enough persistence of vision will 

 have the effect of bringing them together and forming a 

 complete picture. 



From the article in question I gather that Szczepanik 

 devised a way of separating any image formed by an 

 ordinary photographic lens into its component luminous 

 points, of transmitting these points separately, but with 

 enormous rapidity, over wires, and letting the eye recon- 

 stitute them at the other end into the original picture. 



Selenium, it may be said, possesses the peculiar property 

 of transforming waves of light into waves of electricity, 

 so that if rays of light are thrown upon a selenium disc 

 to which insulated wires are connected, it will be found that 

 currents are set up in the wires, and moreover that rays of 

 light differing in colour and intensity give rise to currents 

 which also differ in intensity ; each particular ray having 

 its corresponding current, and no two of them being exactly 

 alike. 



Szczepanik's transmitting apparatus consisted of a box 

 with a camera front and a photographic lens for focussing 

 an image outside the box upon two vibrating mirrors, 

 designed to resolve the image into points and project these 

 upon a selenium disc connected by wires with the receiving 



