AUSTIN: ARC AND SPARK RADIO TRANSMISSION 517 



RADIOTELEGRAPHY. — Further comparison of arc and spark 

 radio transmission. L. W. Austin, U. S. Naval Radio Tele- 

 graphic Laboratory. 



In order to make a comparison of the relative desirability of 

 arc and spark transmission under summer conditions, a test was 

 carried on between the Arlington station and Colon during the 

 months of July and August of the present year. This time was 

 chosen for the test on account of the fact that the signals are 

 weakest at this period of the year, while at the same time the 

 atmospheric disturbances are the strongest^ so that the test may 

 be considered as carried on under the most trying conditions. 

 Hitherto all the long distance tests carried on by the Navy De- 

 partment in connection with Arlington have been made during 

 the winter months, when atmospheric disturbances are at a min- 

 imum and all conditions are favorable to long distance trans- 

 mission. It was especially wished to make a comparison of the 

 relative desirability of arc and spark transmission under summer 

 conditions in order to determine whether the conclusions favor- 

 able to the arc, which had been drawn from the Arlington-Salem 

 tests, would be supported. 



For this work a 100 k.w. Poulsen arc belonging to the Uni- 

 versal Radio Syndicate was available for comparison with the 

 regular rotary gap set of the Arhngton station. The regular 

 experiments began on July 25. The distance from Arlington to 

 Colon is 1780 nautical miles. From the formula deduced from 

 the Brant Rock experiments, the Arhngton signals, at a wave 

 length of 4000 meters, should be faintly audible at this distance, 

 using a sensitive crystal detector and an antenna 200 feet high. 

 As a matter of fact, the signals are just below audibility with 

 ordinary detectors, as is shown from their strength on the more 

 sensitive ticker. This fact may be due to the passage of the 

 waves over Cuba, or to other conditions of transmission in this 

 portion of the world. 



The recei\'ing work at Colon was done by Chief Electrician 

 Meneratti, assistant at the Naval Radio Laboratory. The re- 

 ceiving apparatus used consisted of a Federal receiving set, which 



