136 



RECENT ADVANCES IN WIEELESS TELEGRAPHY. 



It was possible nearly five j^ears ago to send different messages 

 simultaneously v ithout interference, the messages being received on 

 differently tuned receivers connected to the same vertical conductor. 



This result was described in the Times of October 4, 1900, by Pro- 

 fessor Fleming, who, in company with others, witnessed the test. 



A recent imj)rovement introduced in the method of tuning the 

 receiver is that shown in fisr. 11. 



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Fig. 9. 



Fig. 10. 



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There exists at present among the large section of the public con- 

 siderable misconception as to the feasibility of tuning or syntonizing 

 wireless telegraphic installations, and also as to what is generally 

 termed " the interception of messages." According to the accepted 

 understanding, " intercepting "' a message means or implies securing 

 by force, or by other means, a communication which is intended for 

 somebody else, thereby preventing the intended recipient from re- 

 ceiving it. X o w , 

 this is just what 

 has never happened 

 in the case of wire- 

 less telegraph}^ It 

 is quite true that 

 messages are, and 

 have been, tapped 

 or overheard at sta- 

 tions for w h i c h 

 they are not in- 

 tended, but this 

 does not by any 

 means prevent the messages from reaching their proper destination. 

 Of course, if a powerful transmitter giving off strong waves of differ- 

 ent frequencies is actuated near one of the receiving stations, it may 

 prevent the reception of messages, but the party working the so- 

 called interfering station is at the same time unable to read the mes- 

 sage he is trying to destroy, and therefore the message is not, in the 

 popular sense of the word, " intercepted." It should be remembered 



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Fig. 11. 



