THE CAMERA 



139 



NO. 1 NO. 2 



Xo. 1 is a vertical flash. The cut shows the top at the left side. No. 2 shows a flash composed of forty 

 separate discharges. The duration of this flash was about 6/10 second, and the intervals be- 

 tween some of the discharges as low as 1/500 second. The first discharge shows 

 black. The reason for this is not clearly understood at present, but it is 

 supposed to be caused by reversal of the image on the plate, but 

 there are many reasons which oppose this explanation. 



lightning' is seen, and immediately clos- 

 ing the shutter after a flash has passed 

 across the field of the lens. This must 

 be done at night, and when only clearly 

 outlined flashes are seen; when there 

 is much sheet lightning the result will 

 usually be only spoiled plates. 



Photographs obtained in this man- 

 ner do not give us much knowledge of 

 the details and nature of the flashes, be- 

 cause the pictures show only single dis- 

 charges, whereas in reality, most 

 flashes are multiple, consisting of many 

 discharges that follow one another in 



no. 1 x< 1. 2. NO. 3. 



No. 1 shows a horizontal flash broadened by moving the camera. No. 2 is a vertical flash, the dark part 



in the center being a cloud through which it passed. No. 3 is a horizontal flash with one 



branch terminating in the ground — taken with a camera moving up and down. 



