s is four times the inclination of
Mars' orbit and six times the inclination of Jupiter's orbit; and among
the planetoid-orbits themselves the inclinations of some are fifty times
those of others. How are all these differences to be accounted for on
the hypothesis of genesis from a nebulous ring? (5.) Much greater
becomes the difficulty on inquiring how these extremely unlike
eccentricities and inclinations came to co-exist before the parts of the
nebulous ring separated, and how they survived after the separation.
Were all the great eccentricities displayed by the outermost members of
the group, and the small by the innermost members, and were the
inclinations so distributed that the orbits having much belonged to one
part of the group, and those having little to another part of the group;
the difficulty of explanation might not be insuperable. But the
arrangement is by no means this. The orbits are, to use an expressive
word, miscellaneously jumbled. Hence, if we go back to the nebulous
ring, there presents itself the question,--How came each
planetoid-forming portion of nebulous matter, when it gathered itself
together and separated, to have a motion round the Sun differing so much
from the motions of its neighbours in eccentricity and inclination? And
there presents itself the further question,--How, during the time when
it was concentrating into a planetoid, did it manage to jostle its way
through all the differently-moving like masses of nebulous matter, and
yet to preserve its individuality? Answers to these questions are, it
seems to me, not even imaginable.

* * * * *

Turn we now to the alternative hypothesis. During revision of the
foregoing essay, in preparation for that edition of the volume
containing it which was published in 1883, there occurred the thought
that some light on the origin of the planetoids ought to be obtained by
study of their distributions and movements. If, as Olbers supposed,
they resulted from the bursting of a planet once revolving in the region
they occupy, the implications are:--first, that the fragments must be
most abundant in the space immediately about the original orbit, and
less abundant far away from it; second, that the large fragments must be
relatively few, while of smaller fragments the numbers will increase as
the sizes decrease; third, that as some among the smaller fragments will
be propelled further than any of the larger, the widest d