208 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1926 
mospherics undoubtedly come from thunderstorms, many appear to 
come from regions where no such storms are occurring. It is also 
believed that even in thunderstorms some of the heaviest disturb- 
ances do not come from the lightning itself, but the nature of these 
nonluminous sources of such great power is still a matter of 
conjecture. 
