MIRACLES OF SCIENCE 



might be so arranged in time of war that the search 

 light of a hostile ship would discharge the weapon 

 just at the moment when it was so directed as to 

 send its missile to the ship furnishing the source of 

 light. He suggested also that selenium cells might 

 be arranged in such a way as to make possible direct 

 vision over a telephone wire; not the mere sending 

 of pictures, but actual vision of objects, as, for ex- 

 ample, the face of the talker at the other end of the 

 wire. But whatever the possibilities in this direction, 

 no such instrument has yet reached the commercial 

 stage. 



PHOTOGRAPHS BY WIRE AND BY WIRELESS 



Meantime the curious property of selenium has been 

 utilized in a very ingenious manner in the develop- 

 ment of a system of sending pictures by electric wire, 

 the originator of the method being Professor Korn, 

 now of Berlin. The apparatus that he devised was 

 put into practical use as long ago as November, 1907, 

 for the telegraphic transmission of pictures from 

 Paris to a London newspaper; and Professor Korn 

 is now perfecting apparatus with a view of transmit- 

 ting photographs from New York to London. 



The essentials of the process consist of wrapping 

 a photograph made on celluloid about a glass cylinder, 

 and revolving the cylinder in such a way that the 

 focussed beam of a Nernst electric lamp penetrates 

 the successive portions of the photograph, in a spiral 

 path that finally takes in the entire cylinder, just as 

 the needle of an Edison phonograph traverses the 

 close spiral constituting the phonograph record. 



