MEAP URAT ER FES mney aay ee 
3 THE STARRY HEAVENS 411 
no light which falls on the plate, however 
faint, is lost; it is taken in and stored up. 
In an hour the effect is 3600 times as great 
as in asecond. By exposing the photographic 
plate, therefore, for some hours, and even on 
successive nights, the effect of the light is as 
it were accumulated, and stars are rendered | 
visible, the light of which is too feeble to be 
shown by any telescope. 
The distances and magnitudes of the 
Stars are as astonishing as their numbers, 
Sirius, for instance, being about twenty times 
as heavy as the Sun itself, 50 times as 
bright, and no less than 1,000,000 times as 
far away; while, though like other stars it 
seems to us stationary, it is in reality sweep- 
ing through the heavens at the rate of 1000 
miles a minute; Maia, Electra, and Alcyone, 
three of the Pleiades, are considered to be 
respectively 400, 480, and 1000 times as _ bril- 
liant as the Sun, Canopus 2500 times, and 
Arcturus, incredible as it may seem, even 
8000 times, so that, in fact, the Sun is by 
no means one of the largest Stars. Even 
the minute Stars not separately visible to the 
