WIRELESS TELEGRAPHY 



When Professor Lodge heard of the Branly ex- 

 periments he fixed up a little automatic tapper. 

 It worked on the same principle as an electric 

 door-bell. (I wonder how many people ever stop 

 to think how even that simple every-day affair 

 operates.) The effect of this tapping arrangement 

 was to give the slender tube of filings a smart jog 

 every time the electric- waves made them cohere. 

 It was a decoherer. 



The rest was simple. If the battery on the 

 floor could be made to operate the tapper, it could 

 also set a common Morse printing instrument go- 

 ing. According as the series of waves coming 

 down the receiving-wire is short or long, the ma- 

 chine prints a dot or a dash. These you read off 

 on the tape, just as you read the quotations on 

 a stock-ticker, only you have to know the Morse 

 alphabet to understand. 



Ordinarily, the waves are strong enough and 

 their effect clear enough, so that no telephone at- 

 tachment is needed. The clicks can be read off 

 by the ear just as in ordinary telegraphy. But 

 the waves seem to weaken with the distance, and 

 those which had travelled two thousand miles, 

 from Cornwall to Newfoundland, were faint indeed. 

 That was why Signer Marconi held an instrument 

 to his ear. 



The odd thing about it is that had Marconi 

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