Lightning 123 
us than the time necessary for the flash and report of the 
lightning stroke. 
LIGHTNING SNAPSHOTS 
By means of special revolving and wide-view cameras it is 
possible to photograph lightning strokes. It is discovered that 
what appears to be a single stroke is often a series of distinct 
strokes following one another so quickly that they give the 
appearance of a single stroke. One station for getting shots 
of lightning was situated near the Empire State Building. 
Whenever a promising thunderstorm was in the neighbor- 
hood the scientists were rushed out of bed, or away from 
their other tasks, to their skyscraper laboratory in hopes of 
getting a picture, no matter what the time of day or night. 
What price science! Lightning can be photographed, how- 
ever, with an ordinary box camera; special cameras are neces- 
sary only for scientific purposes. 
DANGER! HIGH VOLTAGE 
The voltages developed in lightning strokes are very great 
when compared to those which we use in ordinary electrical 
appliances. It requires about 50,000 volts to produce a spark 
one inch in length. Imagine, then, what a voltage is required 
for a bolt about a half mile long! In color lightning is either a 
brilliant white or a rose pink. Both of these varieties have dis- 
tinct spectra which have been studied with the spectroscope. 
The cause of the light of lightning is not fully understood. Air 
has been heated to very high temperatures in the laboratory, 
but it has never been made so hot that it gives off light of its 
own as in an electrical discharge. It is generally supposed 
that the light is a result of disturbances within the atoms 
themselves caused by the passing electrons of the discharge. 
