x THE STARRY HEAVENS 417 
rate, and observation shows that the lines 
given by the light of the two edges differ 
accordingly. So again as regards the Stars, 
we obtain a similar test derived from the 
EKarth’s movement. As we revolve in our 
orbit we approach or recede any given star, 
and our rate of motion being known we 
thus obtain a second test. The results thus 
examined have stood their ground satisfac- 
torily, and in Huggins’ opinion may be relied 
on within about an English mile a second. 
The effect of this movement is, moreover, 
independent of the distance. A lateral mo- 
tion, say of 20 miles a second, which in a 
nearer object would appear to be a stupendous 
velocity, becomes in the Stars quite imper- 
ceptible. A motion of the same rapidity, on 
the other hand, towards or away from us, dis- 
places the dark lines equally, whatever the 
distance of the object may be. We may then 
affirm that Sirius, for instance, is receding 
from us at the rate of about 20 miles a second. 
Betelgeux, Rigel, Castor, Regulus, and others 
are also moving away; while some — Vega, 
Arcturus, and Pollux, for example — are 
2E 
