418 AUSTIN— ENERGY IN RADIOTELEGRAPHY. [April 19, 



face of the earth with a smaller degree of absorption than the dis- 

 continuous wave trains produced by spark apparatus. In order to 

 test this point, as well as some others connected with arc transmis- 

 sion, a 30-K.W. arc operated with 500-volt d.c. current was obtained. 

 At a wave-length of 4,100 meters this arc produced from 48 to 53 

 amperes in the Arlington antenna. Comparisons were made of the 

 received currents from this arc and from the spark set giving 100 

 to 120 amperes in the antenna. A very careful set of observations 

 on the two types of radiation was made at St. Augustine, the received 

 current being measured by the calibrated detector and galvanometer 

 method. At this distance. 530 nautical miles, no difference in the 

 absorption could be observed, the received currents being simply 

 proportional to the radiation currents in the Arlington antenna. 

 These results were verified by the shunted telephone method, using 

 the slipping contact detector/- at New Orleans and Key West, the 

 latter place being approximately 900 miles from Washington. The 

 receiving apparatus was then placed on the U. S. S. Arkansas and 

 taken to Colon, 1,800 nautical miles from Washington. On the 

 voyage, although the conditions were not favorable for accurate 

 observations, it appeared that during the daytime the arc signals 

 gradually approached those of the spark in intensity. During the 

 two days available for observation at Colon, the arc signals only 

 were heard in the daytime. These observations indicated that at 

 distances above 1,000 miles the continuous waves show a smaller 

 degree of absorption than the waves from the spark. It w^as not 

 possible, however, to draw this conclusion with certainty, since at 

 the season of the year in which the observations were taken, excep- 

 tional days occur wdiich might very conceivably affect the continu- 

 ous oscillations in a dift'erent manner from those of the spark. ^^ 



Further observations were made during the recent voyage of the 

 Salem already mentioned. Here it was found, in verification of 

 our former conclusions, that for distances over 1,400 miles the arc 

 as received in the day time on a special receiver .was equal to or 



" Journ. Wash. Acad., i, p. 5, 191 1. 



"It is frequently observed that at night one type of wave is strengthened 

 more than the other. 



