PHOTOGRAPHING LIGHTNING WITH A MOVING 



GAMER A.« 



By Alkx Labsen. C'liicajio. 111. 



Lic'htning, with its accompaniment of thunder, has always ex- 

 erted a fascinatino- influence on the thinking mind. It is not strange 

 that a people living in an age when the laws of nature were less per- 

 fectly understood should have associated this beautiful and awe- 

 iuspiring natural phenomenon with the powers and attributes of 

 their gods. 



The ancient Norsemen recognized in the rumbling of the thimder 

 the ajjproach of Thor, their most powerful god, in his heavenly 

 chariot, drawn by his two he goats; and in the lightning flash they 

 saw the path cleaved through the air by the never-failing hannner 

 '' JNIjolner," wielded by the mighty arm of Thor when battling with 

 the enemies of the gods, the hammer always returning to his hand. 

 The myth is l)eautiful, and it would seem as if its authors had noticed 

 the peculiar flickering of most lightning flashes and associated it 

 with the forward and return movement of the hannner. 



The princi])al object of this paper is to place before its readers 

 certain facts to account for this flickering of lightning flashes. 



In the latter part of the summer of 1001, while taking somqpordi- 

 nary jDictures of lightning, the idea occurred to the writer while 

 noticing this flickering that if the camera be moved in a circle at 

 right angle to the flash the picture ought to show a widening of the 

 flash, if it was composed of separate parts, and thereby also deter- 

 mine its duration. The attempt to do this was made that year, but 

 without success. It was repeated again in lOO'i, and ou July 17 

 several successful exposures were made which clearly showed that 

 most flashes are composed of several discharges following one another 

 at certain intervals in the path made by the first discharge, ilu' 

 writer was unaAvare at the time that others had experimented in the 

 same line and had published their results. 



aThe study of liuhtning flashes liorewitb presented was aided by a grant 

 from the Ilodgkius Fund of the Smithsonian Institution, 



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