812 



SCIENCE 



[N. S. Vol. XLII. No. 1093 



when he suddenly discovered that an oscil- 

 lator connected to the earth, as described in 

 Fig. 3, was much more efficient than any 

 other form of oscillator in propagating an 

 oscillatory motion of electricity from any 

 given point of the earth to any other point. 

 That discovery gave birth to wireless teleg- 

 raphy. But, nevertheless, this discovery 

 could have been made prior to the time of 

 Hertz by any one who understood the work 

 of Henry and of Kelvin and interested him- 

 self in the study of electrical oscillators of 

 various types. I think that Marconi dis- 

 covered wireless telegraphy; he did not in- 

 vent it. The inventing period in this new 

 art started after the discovery was made 

 and when various problems connected with 

 the development of this new art presented 

 themselves. 



The earliest attempts to advance the new 

 art were in the direction of increasing the 

 distance which could be bridged over by 

 this new method of electrical transmission. 

 As early as 1902 Marconi attempted the 

 bold experiment of sending wireless signals 

 across the Atlantic. These attempts re- 

 sulted at first in an enormous increase in 

 the height of the antennse and the power of 

 the generators which create the electrical 

 oscillations at the sending station. The wire- 

 less structures employed as sending antennse 

 were anything but wireless, and the gen- 

 erating stations which fed them were ver- 

 itable thunder and lightning factories. The 

 roar of the thundering sparks transmitting 

 signals between England and Newfound- 

 land would terrify the whole neighborhood 

 of the transmitting station, and yet at the 

 receiving station there would be only very 

 faint clicks in a very sensitive telephone 

 held over the anxious ear of a skilled oper- 

 ator. Physicists with artistic temperament, 

 that is, with a sense of right proportions, 

 always felt that these thunder and lightning 

 factories had no place in wireless trans- 



mission. Three years ago I suggested that 

 if a little more science were put into the 

 General Electric Company we would soon 

 have a noiseless generator which would re- 

 place those thundering spark-gaps. "Well, 

 the General Electric Company has put a 

 little more science into Schenectady and 

 we have today a generator which can supply 

 any reasonable amount of electrical power 

 in the form of electrical oscillations of very 

 high frequency, say, twenty thousand to 

 two hundred thousand vibrations per sec- 

 ond, and it supplies it smoothly and silently. 

 The horrible racket of thunder and light- 

 ning has disappeared for good from the 

 wireless transmitting stations. 



In the meantime another great and won- 

 derful advance has reached the wireless 

 transmitting station. This advance is so 

 far reaching in its purely scientific aspect 

 that I feel constrained to devote to it a few 

 brief moments. Consider a generator of 

 electrical oscillations sending out from a 

 wireless station at A (Fig. 5) a continuous 

 train of electrical waves ab of high fre- 

 quency or pitch, say fifty thousand periods 

 per second. A person with a telephone 

 receiver at the receiving station B would 

 hear nothing, because the pitch of the re- 



EA fkTH 



Fig. 5. 



V/////j////j//^^jj//////// ^j/jj/^jjjn^/ 



ceived waves is too high. Suppose now 

 that by some means the generator is made 

 to vary the amplitude of the outgoing 



