CONQUEST OF TIME AND SPACE 



At the other end of the circuit the picture is repro- 

 duced on a sensitized paper wrapped about a cylinder, 

 which is traversed spirally by a platinum point con- 

 nected with the electric circuit. When the current 

 is transmitted, it discolors the sensitized paper, 

 through exciting chemical action; when the current 

 is broken the paper remains unchanged. So the net 

 result is the tracing on the receiving drum of a series 

 of dots or short streaks which pass in a close spiral 

 about the cylinder and thus build up the picture. 



The fidelity of the reproduction will depend as be- 

 fore on the closeness of the spiral and the accuracy 

 with which the receiving drum corresponds in speed 

 of rotation to the. transmitting drum. 



In practice the drums are rotated at a speed of 

 about thirty revolutions per minute, and the appara- 

 tus operates with such speed as to record three 

 hundred sharply defined chemical marks per second. 

 Accordingly a picture of considerable size may be 

 built up by the endless spiral of graduated marks in 

 the course of a few minutes. Stated otherwise only 

 a few minutes are required to transmit a picture of 

 whatever degree of complexity from sending to re- 

 ceiving station, as for example, from Paris to London. 



Mr. Baker's telectograph system, which has been 

 in practical operation between Paris and London and 

 between Manchester and London, has additional in- 

 terest in that it can be operated in connection with 

 a wireless apparatus. As yet pictures have not been 

 sent to a very great distance by wireless, but Mr. 

 Baker predicts that wireless transmission of photo- 

 graphs may eventually prove of more utility than the 



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