I-jO 



THE GUIDE TO NATURE 



rapid succession through the path 

 opened by the first discharge. In order 

 to separate these so that they may be 

 seen and studied, it is necessary that 

 the camera be made to move during" the 



the angle of most of the lenses used in 

 ordinary cameras. 



Where exactness is essential, a re- 

 volving table operated by a motor must 

 be used. The plates are developed as 



NO. 3 OF THE PREVIOUS ILLUSTRATION AS TAKEN WITH A STATIONARY CAMERA. 



exposure. By so doing, we change the 

 position of the flashes on the plate, in 

 the same manner in which the image of 

 a landscape is shifted on the ground 

 glass when the camera is turned. So 

 that instead of a single streak on the 

 plate after develooing it, the flash may 

 reveal a number of streaks running par- 

 allel with one another, and sometimes 

 covering the entire width of the plate. 

 The distance between these streaks 

 varies, depending on the time intervals 

 between the flashes, and also on the 

 speed with which the camera is moved. 

 By knowing the speed of the camera 

 and its angle, we can estimate the time 

 between the discharges that form the 

 flash, and also the total duration of the 

 flash. 



Perhaps the reader would like to 

 know how to proceed with the moving 

 camera. The simplest and perhaDS the 

 best way, where exactness is not re- 

 quired, is to move it by hand, holding 

 it slightly elevated in front of the body, 

 swinging it from one side to the other 

 when the flashes are vertical, and up 

 and down when they are horizontal. 

 By practice, we can acquire a fairly 

 uniform speed, and can make one swing 

 a second, moving the lens through an 

 arc of about sixty degrees, that being 



they are in ordinary work, contrast and 

 details being looked for. 



Lightning photography offers an un- 

 ending variety, no two flashes being 

 alike, and if the thousands of amateurs 

 that are scattered far and wide would 

 take up the subject, and spend a few 

 hours when opportunity offers in gath- 

 ering these mysterious messages from 

 above, they would not only add to their 

 collection of curios, but they might be 

 instrumental in aiding science to solve 

 some of the questions connected with 

 atmospheric electricity. 



A Yellow Columbine. 



Baltimore, Maryland. 

 To the Editor: 



You mention in your June issue co- 

 lumbine as being red, blue and white. 

 I have two plants in my yard that pro- 

 duced a beautiful yellow blossom. 

 Everv one who saw them acknow- 

 ledged that they never had seen a yel- 

 low. Have you? 



Yours truly, 



Tohn A. Davis. 



I love you because you love the 



things I love. 



-Alice Hubbard. 



