204 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1926 
comes in some way from above has also been held by Weagant.’ 
Mosler,® while ascribing the disturbances to thunderstorms, concluded 
in contradiction to the ideas of Eccles, that thunderstorms could give 
rise to atmospherics only over a radius of about 60 miles. This 
limitation in distance was very probably due to insensitive appara- 
tus. A very systematic study of thunderstorms and atmospherics, 
undertaken by the British Meteorological Office and the Admiralty, 
has apparently settled the fact that thunderstorms can be located 
with modern apparatus up to about 1,500 miles.® 
There is still much difference of opinion as to the proportion of 
atmospherics which is due to thunderstorms. Professor Appleton, 
at a symposium *° on atmospheric ionization and radiotelegraphy, 
November 28, 1924, expressed the opinion that practically all atmos- 
pheric disturbances might be produced by thunderstorms somewhere 
in the world. 
It is undoubtedly true that thunderstorms produce many atmos- 
pherics, but it is not by any means certain that the lightning flashes 
themselves are always the actual sources. There is a widely pre- 
vailing idea among radio operators that the lightning fiash often 
produces only a harmless click in the telephone receivers. I have 
made some observations during thunderstorms, using a coupled cir- 
cuit with rectifying vacuum tube and galvanometer, which indi- 
cated that lightning flashes, even within 3 or 4 miles, were not as 
powerful in their effects on the receiving apparatus as many of the 
disturbances which occurred when no flashes were apparent. This 
comparatively feeble effect of the flashes is difficult to understand 
if the current rise at the beginning of the flash is as steep as is often 
assumed. but would be understandable if the lightning discharge 
curves were of the form and duration of the atmospheric disturbance 
curves observed by Appleton and Watt (figs. 1-5). On the other 
hand, it is quite possible that the small deflections from the light- 
ning flashes were due to a paralysis of the detector tube, a phenom- 
enon which often occurs when the tube is exposed to very high elec- 
tromotive forces. It must, therefore, be concluded that the connec- 
tion between lightning and atmospherics is still not clear, and val- 
uable work can be done by anyone who will watch the lightning and 
listen to the atmospheric crashes from thunderstorms in the neighbor- 
hood.*? 
At the London Physical Society symposium already mentioned, 
Prof. C. 'T. R. Wilson discussed the probability of there being dis- 
METOC. Te othe Wea pes DO ts LOL: 
8 Wlektrot. Zeits., 1134. 1912. 
® World Power, 3: 20. 1925. 
10 Proc. Phys. Soc., London, 37: 2D-50D (appendix). 1925. 
Jt appears that for wave lengths below 1,000 meters, when thunderstorms are within 
a few miles, the visible discharges produce most of the strong disturbance crashes, 
