840 The Outline of Science 



Fleming valve, to rectify the oscillation to check all the 

 negative pulses and utilise all the positive to let only one 

 sign through. Thus they got the vacuum valve. But soon 

 this was improved by Lee Forest into a magnifier ; so that an 

 original impulse, exceedingly weak, could be strengthened a 

 hundred or even a thousand times by using the electrons as 

 relays and putting a number of relays in series. 



So also for transmitting the magnifying device was 

 available. The electric impulses from the first valve, the one 

 directly actuated by the microphone, need not be given to the 

 ether ; they could be used to stimulate another valve, so as to 

 increase their intensity until the waves generated were power- 

 ful enough to be allowed to rush across the Atlantic. That 

 they were able to do in the fraction of a second. And there, 

 though what arrived was only a feeble residue, since they had 

 spread far and wide by that time, yet they preserved all their 

 peculiarities intact; every pulse of the speech was retained 

 and could be reproduced, and by adequate magnification 

 could be made easily audible. 



BIBLIOGRAPHY 



BANOAV, The Elementary Principles of Wireless Telegraphy. 

 BUCHER, Practical Wireless Telegraphy. 



FLEMING, The Wonders of Wireless Telegraphy and Waves and Ripples in 

 Water, Air, and flLiher. 



