1913] AUSTIN— ENERGY IN RADIOTELEGRAPHY. 413 



cent, and 60 per cent, of the calculated values ; that is, the effective 

 length of the equivalent Hertzian oscillator is apparently too great. 

 This may be due either to the shape of the antennas or to the fact 

 that the earth beneath them is not properly conducting as is assumed 

 in the derivation of the formula. If the last supposition is true, a 

 better agreement between the theoretical and observed values ought 

 to be obtained in the case of ships' antennas where the ground con- 

 sists of sea water. Unfortunately, however, in the case of warships 

 at least, the problem is complicated by the steel masts and rigging 

 which it is generally supposed tend to absorb a portion of the ra- 

 diated energy. It is to be hoped that some time in the near future 

 experiments may be carried out on ships free from these disturbing 

 influences. It seems very possible that the shape of the antenna 

 and not the conductivity of the ground is the real cause of the diver- 

 gence from the theoretical values. In the case of a flat top or um- 

 brella antenna we have nearly the condition of two plates of a con- 

 denser in which the distance between the plates is not large compared 

 with the plate dimensions. Under these circumstances it is certain 

 that the electric field distribution will not be the same as that due 

 to one of the spheres of a Hertzian oscillator placed at the center 

 of capacity of the antenna system. However this may be, the ex- 

 periments show that the length of the oscillator equivalent to the 

 antenna of a land station is somewhat less instead of greater than 

 the height to the center of capacity. 



Observations at Greater Distances. 



In the Brant Rock experiments already mentioned it was found 

 that for distances of more than 100 miles over sea water a meas- 

 urable absorption of the radiated energy took place, so that to repre- 

 sent the received current the full form of equation (i) including 

 the absorption factor must be used. In the experiments mentioned, 

 observations were made on the scout cruisers up to about 1,200 

 miles. The figure (Fig. 2) shows that at a distance of 1,000 miles, 

 at a wave-length of 1,000 meters, the received current was only one 

 seventeenth of what would have been received if there had been no 

 absorption, and since the strength of signal in the telephone is pro- 



