368 The American Geologist. December, i904- 
if we divide Rhea's velocity, 323.5 miles a minute, by 9, we 
find that 35.8 miles a minute would be the velocity by which a 
moon would move around Saturn at a distance of about 26 
million miles. Now since this is still nearlv the velocit} of the 
Moon around the Earth, it seems that a moon would revolve 
around Saturn at a considerable greater distance than 26 mil- 
lion miles. It appears, thus, that the mathematical computa- 
tion mentioned above has come very close to the truth. We 
need not go to any extreme, however ; it is satisfactory to 
know, that we have assured ourselves of the fact, that Saturn 
can overpower and attract small planets within a radius of at 
least 26 million miles. 
The discovery of Saturn's ninth moon by professor Pick- 
ering in 1899 and the fact that this moon still has a distance of 
8 million miles most strongly indicates that Saturn may have 
received its moons in the manner which we have now de- 
scribed. This appears still clearer when we remember that 
the small planets, which have an average distance from the 
Sun of 600 to 700 million miles, intersect the orbit of Saturn 
It their aphelia, and those which have an average distance of 
1,000 to 1,200 million miles will intersect it at their perihelia; 
besides that, Saturn himself varies his distance about 100 mil- 
lion miles, and sweeps along in his orbit with a gravitative 
sphere so great that it measures about 56 million miles in di- 
ameter within which no small planet can come without being 
captured. 
Having now come to an understanding of this matter, we 
understand also, that the twO' most distant moons, especially^ 
are continually being drawn closer to the planet, and that 
the one farthest away is attracted most rapidly. The last one 
may, for all we know, just have been captured when it was 
discovered. But it is also possible, that it began its revolu- 
tion aroimd Saturn at a distance of about 20 million miles or 
more. Moreover, it is good reason to believe that small plan- 
ets which yet have their orbits around the Sun, will in the fut- 
ure be discovered as moons of Saturn ; and we may also con- 
clude that what is true about Saturn in this respect is true 
about the more distant planets also. 
Finally it may be of some importance to call attention to 
the fact, that the attraction which Saturn exerts on its distant 
