REMARKABLE LIGHTNING PHOTOGRAPHS 



By C. G. abbot 



Secretary, Smithsonian Institution 



(With One Plate) 



About 30 years ago the Institution made grants from the Hodgkins 

 Fund to Alexander Larsen, of Chicago, to promote his studies of 

 lightning flashes, in which he made many photographs of lightning, 

 using a moving camera. Mr. Larsen contributed an illustrated paper 

 on this subject to the Appendix to the Smithsonian Report for 1905.* 

 He continued these experiments for several years after 1905, and in 

 the year 1908 sent to this Institution the two extraordinary photo- 

 graphs shown in plate i , with the following notes : 



The print marked no. 4 [pi. i, fig. i] is from a plate which was the fourth 

 one exposed on that occasion [May 29, 1908]. The camera at the time was moved 

 with a speed of i revolution in 5 seconds. The flash was a very bright one, 

 but it was so sudden and vivid that I did not notice anything peculiar about it. 

 The thunder accompanying it was very sharp and sudden, like the report from 

 a cannon. The interval between lightning and thunder cannot be given accurately ; 

 it was less than a second, and probably more than half a second. 



The picture of this flash is very remarkable; I have never seen any one 

 resembling it, and would prefer to call it a tubular flash on account of its 

 general shape and large diameter, measuring, as it does, over 3 mm at its widest 

 part, and about 2 mm at its narrowest ; this great width cannot be accounted 

 for, to be caused by the movement of the camera; the uniformity of the width, 

 both in the vertical and horizontal portion of it, disproves that idea. It seems 

 to be a practically instantaneous flash, coming from a NW. direction in an almost 

 straight line at an angle of 32°, then bending suddenly, moving upward again, 

 bending in a SW. direction, moving downward, again turning eastward making 

 another bend, moving south slightly upward, then turning downward again. 



If we assume that the nearest portion of this flash took place at a distance of 

 1,000 feet, which in my opinion would be a conservative estimate, we are con- 

 fronted by the remarkable fact that the diameter of this flash would be over 

 18 feet. (The angle of the lens is 43°.) 



I am absolutely at a loss to account for this remarkable flash ; it does not 

 appear to be a ribbon flash, which can be accounted for by the movement of the 

 lightning path, by air currents, so will have to defer my opinion until some 

 future time, and leave it to others who may be able to give a plausible explanation. 



^Ann. Rep. Smithsonian Inst. 1905, pp. 1 19-127, 6 pis., 1906. 



Smithsonian Miscellaneous Collections, Vol. 92, No. 12 



