518 



AUSTIN: ARC AND SPARK RADIO TRANSMISSION 



is especially efficient at the longer wave lengths, a slipping con- 

 tact ticker, and a Fessenden heterodyne. The regular antenna 

 of the Colon station, 180 feet high and of about 0.004 m.f. 

 capacity, was used for the work. The arc signals were sent out 

 from Arlington at wave lengths of 4000, 5000, 6000 and 7000 

 meters. Two wave lengths were used with the spark, 3500 meters 

 and 2500 meters. The latter, however, proved so unsatisfac- 

 tory at this distance that its use was abandoned after the first 

 few days. 



On account of the continuous atmospheric disturbances quan- 

 titative comparisons were of little value. The following table 

 gives the number of schedules sent at the various wave lengths, 

 and the corresponding number received: 



The table shows that the best results were obtained with the 

 arc at 7000 meters, every schedule being successfully received. 

 The same is true of the 5000 meter arc waves, but in this case all 

 the work was done at night which prevents its being properly 

 compared with the other schedules. The 4000 meter arc and 

 the 3500 meter spark waves, which may be fairly compared, were 

 received with the same degree of regularity and were of approxi- 

 mately the same strength as compared on the slipping contact 

 ticker. In this connection it must be remembered, as will be 

 explained later, that while 90 per cent of the spark schedules 

 were weakly audible on the heterodyne or ticker, practically 

 none of the messages were readable. It appears from the report 

 that 50 per cent of all the arc messages sent at the various wave 

 length, that is, 65 per cent of the arc schedules heard at all. 



