WIRELESS TELEPHONY FESSENDEN. 



193 



It may be noted that the absorption is a maximum at a frequency 

 of about 200,000 per second, nine hundred and ninety-nine thou- 

 sandths (0.999) of the energy being absorbed at this frequency dur- 

 ing daylight, while for a frequenc}' of 50,000 the absorption does 

 not appear to be appreciable. Longer experiments, of course, might 

 show some absorption, but in any case it is of a different order from 

 the absorption for the shorter ware lengths. 



Experiments were then made between Brant Rock and the West 

 Indies, a distance of 1,700 miles, during the spring and summer of 

 1907, It was found that the results were of the same character, i. e., 

 that while there was greater absorption for frequencies of 200,000 

 there was comparatively little absorption for frequencies in the 

 neighborhood of 80,000, and messages were successfully transmitted 

 in daylight with this latter frequency. No messages were received in 

 daylight with the higher frequency, though messages transmitted 

 from the same station and with the same power and frequency were 



-100 :i 



200.000 100.000 



FREQUENCY 

 Fig. 8. — Absorption curve, tests between Brant Rock and Washington. 



officially reported as having been received at Alexandria, Egj^pt, a 

 distance of approximately 1,000 miles. 



The fact that these experiments were made during summer weather, 

 and the receiving station was in the Tropics, and the fact that the 

 distance, 1,700 miles, was practically the same as that between Ire- 

 land and Newfoundland, definitely settled the question as to whether 

 long-distance wireless telegraphy was a commercial possibility or 

 not, and the results were therefore published.'* 



Since the publication of the above results, transmission has been 

 accomplished by means of these long waves over still greater dis- 

 tances during daylight. Mr. Marconi, early in October, 1907, aban- 

 doned the short-wave lengths previously u.sed and adoj)ted one over 

 two units in length, and immediately succeeded in operating between 



"The Electrician (London), July 26, 1907. 



