370 The American Geologist. 
December, 1904. 
which causes the large inclination of the orbits of the minor 
planets to the ecliptic between Mars and Jupiter, but which 
diminishes as the distance from the Sun increases. We may 
mention, also, as a fourth factor of somewhat minor im- 
portance, that the large comets, far from the Sun, may at 
times, draw the minor planets out of their orbits and thus 
put them in danger of being captured afterwards by the ma- 
jor planets. 
Let us remember, then, that the small planets that reach 
the orbit of Neptune at their aphelia, reach or approach near 
the orbit of Uranus at their perihelia ; and that the same class 
of bodies, which reach Uranus at their aphelia, reach in 
many cases, Saturn at their perihelia. This shows clearly 
that the small planets far out in the sea of ether, where the 
large planets rule, run a greater risk of being captured than 
those in the vicinity of Jupiter. Those large distant planets 
have for the same reason, greater opportunities to enrich 
themselves with moons than, for instance, Jupiter has. This 
opportunity becomes still greater by reason of the fact that 
the minor planets out there move in orbits analogous to the 
major ones and are, consequently, subjected to the attrac- 
tion of these for a greater distance of their orbits than is 
the case in the inner part of the solar system. 
The reader will then, finally, remember the fact, that a 
smaller planet which reaches or intersects the orbit of a 
larger one cannot escape being captured eventually by the 
larger one and being made its satellite; and that this has at 
some distant time happened to the Earth's Moon, and, in fact, 
to all the moons of all the planets. 
(To he continued.) 
