258 The Evolution of the Solar System. [May, 
endorse the statement. But I am constrained to conclude 
that my unknown critic is the exception which makes good 
the rule that “ No class of men, however highly instructed, 
is wholly free from faults of judgment and taste.” 
II. THE EVOLUTION OF THE SOLAR 
SYSTEM. 
By Charles Morris. 
f N the nebular hypothesis of the formation of the Solar 
System it is argued that, in an original vast expanse 
of nebulous matter, centripetal attraction set up rotation 
of the mass as a whole ; that speed of rotation and density 
of aggregation increased together ; that eventually ring after 
ring of condensed matter separated from the outer edges of 
the rotating disk ; and that, finally, these rings broke up, 
and their materials aggregated into the planetary masses. 
In my article on “ The Evolution of the Spheres,” in the 
“ Journal of Science ” (March, 1881), I have temporarily 
assented to this view ; but a fuller consideration of the sub- 
ject requires that a somewhat different view be taken. In 
such a mass of nebulous matter homogeneous diffusion 
would be simply impossible. Yet if there were heterogeneous 
diffusion the force of centripetal attraction could not be 
confined to the centre of the mass, but must also display 
itself in minor portions of the mass. There would un- 
doubtedly be a general centre of atraCtion, affecting the 
mass as a whole ; but there would also be minor centres of 
attraction, affeCting certain portions of the heterogeneous 
mass. Thus, while the nebula as a whole condensed and 
rotated around its centre, its constituents must also have 
set up an independent condensation and rotation of their 
own ; the tendency being for the vast mass to separate into 
many smaller masses, each of which, while yielding to the 
central attraction, pursued its own independent interior 
development. 
Nor would these minor masses display any similarity in 
size. In a huge heterogeneous mass of nebulous matter 
