TELEGRAPHY OF PHOTOGRAPHS BAKER. 



267 



Tl A! £ of dXPOSUfKL 



COM P £ VS/IT /ON 



Late in 1908 Prof. Korn introduced his telautograph, in which a 

 Caselli transmitter, such as already described for the telectrograph, is 

 used, and a line sketch or half-tone photograph is attached to the 

 drum. The receiver is similar to that used in the selenium machines, 

 a spot of light cast on a revolving sensitive film being shut off every 

 time current flows through 

 the wire of the galvanometer 

 and displaces it. When dis- 

 placed the shadow of the 

 wire falls over a fine slit 

 placed in front of the film, 

 and so prevents the light 

 from passing through to it. 

 A line sketch transmitted 

 from Paris to London in this 

 way is now shown (pi. 2, fig. 

 2). The methods of syn- 

 chronizing the sending and 

 receiving cylinders is the 

 same as that used in the telec- 

 trograph; but Prof. Korn"s 

 work was done prior to mine, 

 and his arrangements were 

 therefore copied by me. Sim- 

 ilar methods have been 

 adopted for many years, how- 

 ever, in certain systems of 

 ordinary telegraphy. 



There is a great deal of 

 interesting matter connected 

 with the efficiency of the gal- 

 vanometer-receiving appara- 

 tus, and the vast amount of 

 careful work done by Prof. 

 Korn to increase it, which 

 time quite forbids my men- 

 tioning, and I will therefore 

 pass on to the latest phase of 

 phototelegraphic work — the experiments now being carried out to 

 effect wireless transmissions. 



The wireless apparatus for transmitting sketches, writing, or 

 simple photographic images over distances up to about 50 miles may 

 perhaps be looked upon as rather rudimentary, but I shall be able to 

 show, from actual results, that it is at any rate practicable, and it is 

 certainly more simple than any method based on later wireless re- 

 searches. 



Fig. 4. 



