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AUSTIN— ENERGY IN RADIOTELEGRAPHY. 



415 



about 2,100 nautical miles. The results of the measurements are 

 shown in Fig. 3. The wave-length used by Arlington was 3,900 

 meters, and the average sending current was no amperes. The 

 effective height of the Arlington antenna was 400 ft., while that of 

 the Salem was taken as 130 ft., this being the value which was used 

 in the calculation of the formula of the Brant Rock test. This is 

 probably somewhat too high but is retained in the present calculation 



Fig. 3. 



for purposes of comparison. The curve of the figure is calculated 

 from Tables XVL and XVIa. of the article already cited. ^"^ The 

 observed values of the received currents, as indicated by the crosses 

 in the figure, were calculated from the audibility measurements made 

 by the shunted telephone method on the electrolytic detector in 

 exactly the same way as in the Brant Rock experiments, except that 

 on account of the increased efficiency of the receiving set, the least 

 audible antenna current was taken as seven microamperes instead 

 of ten. The observer was Mr. Lee, who also took the most impor- 



"" Bulletin Bureau of Standards, 7, p. 315, 1911. 



PROC. AMER. PHIL. SOC, LII, 210 I. PRINTED JULY l8, I913. 



