CONCERNING THUNDERSTORMS 



645 



brighter than others, namely, those where taneous, or that they appeared to quiver, 

 the waviness is in the hne of sight. In flicker, or vibrate, or that they appeared 

 this way, what was in the first instance a stationary or persisted for some seconds, 

 single streak of lightning appears a Such observations, made by various 

 fraction of a second later a string of observers living in different lands, evi- 

 luminous points. dently indicate that there was something 



The reader may question the statement peculiar about the discharges they saw, 

 as to the column of air 

 remaining luminous, but 

 this fact has been pro\'ed 

 over and over again, and 

 is very easy indeed to 

 show. All one has to do 

 is simply to point the 

 camera in the direction in 

 which it is considered a 

 flash will appear, and keep 

 on mo\-ing the camera to 

 the right and left, pendu- 

 lum fashion. As it is 

 known that a flash is 

 instantaneous the move- 

 ment of the camera will 

 have no effect on its image 

 on the photographic plate. 

 If, however, the air chan- 

 nel remains for a brief 

 moment luminous, then 

 it will not only leave a 

 trail but the different 

 portions of it will indi- 

 cate various degrees of 

 intensity. 



Such a method as has 

 been above described was 

 used to secure the photo- 

 graph shown in the illus- 

 tration on page 644, and 

 it will be noticed that, 

 not only is there a very 

 distinct trail left by the 

 incandescent air, but there 

 are considerable differ- 

 ences of brightness at the 

 more curvy parts of the flash 

 graph was taken by M. Emile Touchet, 

 at Paris, on April 12, 1904. 



The photographic plate used in this way 

 thus tells us that •• beaded " hghtning or, as has been stated by the best authori- 



Photoirraph by AUx. Lancn. 

 A MULTIPLE LIGHTNING FLASH. 



Photographed with a revolving camera, showing the numerous components 

 involved. Notice the parallelism of all the discharges. 



The photo- 



otherwise they would not have drawn 

 attention to them. 



It has been already mentioned that a 

 single flash of lightning is instantaneous, 



is only an ordinary flash of lightning 

 after all. 



The ne.xt and last point to which 

 attention may be called is an astonishing 

 fact that the camera has revealed to us. 



It has sometimes been remarked that 

 lightning discharges were not instan- 



82 



ties, it occupies at the most joTjWtt o^ ^ 

 second. Such a flash, if it did flicker, 

 could not be seen to do so, as the inter\-al 

 of time is too short for such an observation 

 to he made. Single flashes are therefore 

 incapable of explaining the peculiarity 

 noticed. What about double or triple 



