I9I3-] AUSTIN— ENERGY IN RADIOTELEGRAPHY. 419 



somewhat better than the spark, notwithstanding the fact that the 

 spark radiation current at ArHngton was considerably more than 

 twice as great as the corresponding arc current. This normally, if 

 the absorption had been equal for the two types of radiation, would 

 have made the spark signals more than four times stronger than the 

 arc, the amplitude of signal being proportional to the square of the 

 high frequency current. Regular communication with both arc and 

 spark was continued up to 2,100 miles in the day time. Several times 

 day signals were heard at greater distances, and in these cases the 

 arc was uniformly louder. The night signals were heard all the way 

 to Gibraltar. 



U. S. Naval Radiotelegraphic Laboratory, 

 April, 1913. 



