CONQUEST OF TIME AND SPACE 



practical Corking service between Chicago and Mil- 

 waukee had been put into operation. Nevertheless 

 the wireless telephone has not made its way as a com- 

 mercial mechanism as rapidly as might have been 

 anticipated. 



AUDIBLE LIGHT 



The impulse that comes by wireless, like that 

 which flashes over the telegraph wire, is only a puls- 

 ing of energy that in itself conveys no definite mes- 

 sage except as it is broken into longer and shorter re- 

 lays, so to speak, in the familiar sequence of the 

 Morse alphabet, or is translated into sound-waves by 

 the telephone receiver. It is wonderful enough in 

 all reason, that these impulses can be translated into 

 words; but this is not quite the ultimate achievement 

 at which the inventor aims. Ever since the tele- 

 graph was devised, and in particular since the inven- 

 tion of the telephone, men have dreamed of the 

 possibility of doing for the eye what the electric 

 current does for the ear; in other words, they have 

 sought a means of transmitting visible as well as 

 audible messages. 



An inkling of the curious possibilities of inter- 

 changing sight and hearing is given by an apparatus 

 recently devised by an imaginative English physi- 

 cist, Dr. Fournier d'Albe: an apparatus that enables 

 a blind man to distinguish between light and dark- 

 ness, and even under certain circumstances to recog- 

 nize the presence of opaque objects at a distance. In 

 a recent public test of the apparatus, a blind man 

 standing in the center of a room was able to count the 



