Astronomy. 999 
so near the sun as to almost graze his surface in passing, would 
have a velocity of about 390 miles per second, which is within 
eighty-six miles of that required. ; 
t must be borne in mind, however, that the 476 miles per sec- 
ond is the velocity at the moment of collision. But more than 
one-half of this velocity, or 274 miles per second, would be derived 
om their mutual attraction as they approached each other. We 
have consequently to assume an original or projected velocity of 
only 202 miles per second. If the original velocity was 678 per 
second, this, with the 274 derived from gravity, would generate 
an amount of heat which would suffice for 200,000,000 years. 
ence? It is just as easy to conceive that they always existed in 
motion as that they always existed at rest. In fact, this is the 
only way in which energy could remain in a body without dissipa- 
tion into space. Under other forms a certain amount of it is 
ace. 
_ The theory that the sun’s heat was originally derived from mo- 
tion in space is, therefore, for this reason, also more In harmony 
n 
the sun could have derived his heat. e one is gravitation, the 
other motion in space. The former could have afforded only 
about 20,000,000 or 30,000,000 years’ heat, but there is in reality 
no absolute limit to the amount which may have been derived from 
velocity of motion. And when we take into consideration the 
magnitude of the stellar universe, the difference between a motion 
of 202 miles per second, and one of 1,700 miles to a great ex 
na a and the one velocity becomes about as probable as 
e other. 
It may be urged as an objection to the theory that we have no 
experience of bodies moving in space with such enormous — 
ties as the above. This objection, for the following reason, 18 © 
No body moving with a velocity exceeding 400 miles per secon 
i er of our solar system; and beyond our nia 
tem there is nothing visible but the stars and_ bule. se 
Stars, however, are suns like our own, 
