Prof. D. Kirkwood on the Nebular Hypothesis. 177 
former, and that infinitely.” 
Objections to the Nebular Hypothesis. 
1. The Satellites of Uranus.—It has been objected to the ne- 
bular hypothesis that it cannot be reconciled with the retrograde 
motion of the satellites of Uranus. We reply that in every in- 
stance, so far as we know, the motions of secondary planets are 
performed in planes nearly perpendicular to the axis of the pri- 
mary, but that in no case, with the single exception of Jupiter, 
is the axis of a primary planet nearly perpendicular to the plane 
of its own orbit. The earth’s axis is inclined more than twenty- 
atmos, heres of the sun and planets at their formation, they must 
scribed spirals, and consequently fallen on the bodies, 
Pa : Consequence of their fall, caused the planes of the orbits 
) 
m Bare order of the system, by some foreign law or occurrence.” 
oe While the hypothesis requires in general that the direction 
of thei ll as that of the orbital motions 
their satellites, should be the same as that of their revolution 
ok Meee of the World, Harte’s Translation, vol. ii, Pp 
First Riema Be Important Points Relating to th 
Ate oy cP 10 
, B64. 
e System of the World. 
‘SECOND SERIES, Vol. XXX, No. 88—SEPT., 1860. 
‘. 
