Nebular Theory. — Mistoekles. 233 
east. Wo would expect that I Icrbcrt Spencer atul other phi- 
losophers should have understood this ! 
Here we may safely conclude that the rotation of a nebula 
cannot he caused in the manner that this theory claims; still it 
may be interesting^ to consider, in this connection, some of the 
other consequences resulting from that hypothesis. 
The ethereal matter, as we may most properly call it, 
through which the nebular stuflf, attracted towards the center, 
must pass, and the resistance developed by this motion, must 
necessarily be the same, no matter in what direction the motion 
takes place, since it is the motion itself which creates the re- 
sistance. A motion towards the side of the center must, there- 
fore, meet the same resistance as the one moving straight to- 
wards the center. Since the resistance, thus, will be the same, 
no matter in what direction the nebular stuflf is moving, we are 
forced to conclude, that its motion in any other direction than 
that determined by the law of gravity, is as impossible as^ for 
water to run up hill. 
We shall find, further. If we accept the hypothesis in ques- 
tion, that the resistance which was a consequence of the con- 
traction and sinking of the matter, was coexisting only with 
the medium which caused it. Xow, then, if we direct our at- 
tention to fully condensed and encrusted bodies, as for ex- 
ample the earth, we cannot escape the impression that here, at 
least, the above mentioned medium must long aso have ceased 
to exist as a means of resistance to the contracting matter ; for 
the contraction has practically stopped. In regard to the 
Earth, we can, consequently, not speak of any rotation of mat- 
ter around the center ; hence the Earth itself should not rotate, 
but it does rotate, nevertheless, and with a speed of about 17 
miles a minute. 
In the discussion of this theory, to which many of the 
astronomers still cling, it is also of great importance to call 
attention to the fact, that planets of about the same size ought 
to rotate with about the same velocity, with this dift'erence. that 
a younger one ought to rotate faster than an older one, and that 
the Sun, which, it is claimed, is still a glowing mass, should 
rotate faster than any of the planets. Venus, which, accor [- 
ing to the nebular hyi)othesis, is younger than the Earth, 
should, consequently, surpass this body in the rapiditv of its 
