CONCERNING THUNDERSTORMS 



643 



illustration. This beautiful photograph, 

 showing a great number ot brilliant flashes 

 literally pouring down i'ronr one portion 

 of a cloud, was taken at Vereeniging, in 

 the Transvaal, by Mr. T. N. Leshe. 



opposite direction. Many observers of 

 lightning have stated that they have seen 

 such flashes, and were certain that the 

 direction of the discharge \\'as upwartls ; 

 but their cases were generally looked upon 



Another fine example illustrating several as non proven, not only because no photo- 

 flashes scattered over a wider area is that graphs displayed this peculiarity, but 

 shown on page 642. This photograph was because it was considered impossible lor 

 taken durnig a storm which passed 

 over Sydney Harbour, in Austraha. 

 in August, 1892. It was taken by 

 the late Mr. H. C. Russell, and is 

 one of many which he succeeded in 

 securing. 



It may be mentioned here that 

 the branches in lightning flashes are. 

 so to speak, leaks in the main 

 stream ; all the electricity is not able 

 to pass quickly enough through the 

 main channel, and so has to find 

 other outlets along lines of least re- 

 sistance. An approximate simile 

 may be found in a leaky garden hose 

 pipe when the tap is turned full on. 

 The pressure is so great that the 

 wate^ cannot pass through the pipe 

 sufficiently quick, so squirts out at 

 those parts of the pipe where it can 

 escape easiest. In the case of light- 

 ning discharges, even the branches 

 divide and subdivide again, and the 

 current in these cases becomes so 

 dissipated that the earth is often 

 never reached by any of them. 



A good instance of this is seen 

 in the photograph here reproduced, 

 where the branches on both the right 

 and left hand sides split up into 

 several minor branches and vanish 

 in the air. This interesting photograph the eye to differentiate between an upward 

 was secured by Mr. Paul Georgi at 



A RAMIFIED FLASH 



Showing that some branches never reach the ground in conse- 

 quence of the dissipation of the electricity. 

 Radebeul, near Dresden, by Mr. Paul Georgi. 



Taken at 



Radebeul, near Dresden. 



In all these photographs of lightning 

 which show branches the flashes were 

 discharges from cloud to earth. This 

 direction of the electric current is estab- 

 lished by noting the direction in which the 

 branches leave the main stream. Thus, if 

 the reader looks at the above picture, it 

 will be seen that they point downwards, 

 and thus indicate a downward discharge, 

 or, in other words, a cl(nid-to-earth flash. 

 The majority of flashes which have been 

 photographed all indicate such downward 

 discharges, but a few cases ha\'e been met 

 with where the current flowed in the 



or downward discharge. 



Tennyson was e\-idently con\'ersant 

 with tlie notion that lightning discharges 

 sometimes were directed from the earth 

 to the sky, for in Becket he wrote : 



" Ah, Thomas, 

 That lightniiig.s that we think are only Heaven's 

 Flash sometimes out of earth against the sky." 



That earth-to-cloud flashes do occur is 

 now. in vay o])ini()n. beyoinl doubt, antl the 

 best exam])le which has been photographed 

 is that which \\'as secured by Monsieur 

 G. Mesmer, at Paris, on Jul\' 31. 1004. 

 This photograph is reproduced on jnige 

 644. Unfortunately the flash was not 



