10 D. Kirkwood on certain Harmonies of the Solar System. 
- 2. Granting the existence of an ethereal medium, it would 
seem unphilosophical to ascribe to it one of the properties of a 
material fluid—the power of resisting the motion of all bodies 
moving through it—and to deny it suc He bec in other re- 
spects. ts condensation, therefore, about the sun and other 
large bodies must be a necessary consequence 
3. This condensation existed in the primitive solar spheroid, 
before the formation of the planets: the rotation of the spheroid 
would be communicated to the ether co-existing with it: hence, 
during the entire history of the planetary system, the ether has re- 
. This condensed ether must participate in the progressive 
motion of the solar system 
5. Even if we reject the doctrine of the pains: oo of the 
lanetary system from a rotating nebula, we must still regard 
the density of the ether as increasing to the center of the system. 
e sun’s rotation, therefore, would communicate motion to the 
first and denser portions ; this motion would be transmitted out- 
ward through successive strata, with a constantly diminishing 
angular velocity. The motion of the planets themselves through 
the medium in nearly circular orbits would concur in imparting 
to it a revolution in it same direction. 
6. Whether, therefore, we receive or reject the nebular hy- 
pothesis, the Beaders "of the ethereal medium to bodies moving 
in orbits of small eccentricity and in the iret of the sun’s 
Totation, becomes an infinitesimal quantity. 
7. The doctrine of a resisting medium is not generally ac- 
cepted by astronomers as an established fact, “It is manifest,” 
says an eminent writer, “that more extensive indications of such 
a medium must be discovered before the problem of its existence 
can be considered as having received a definitive solution. It 
has not yet affected to a sensible extent any of the other celes- 
tial bodies, and, until such is found to take place, the question 
relative to it must remain in abeyance.” 
Il.—Tne Piayetary Distances. 
As long ago as the commencement of the seventeenth century, 
the celebrated Kepler observed that the respective distances of 
the planets from the sun formed nearly a regular poe 
e series, however, by which those i stances were expre 
ke uired the interpolation of a term between Mars and Ju Sather 
_ a fact which led the illustrious German to predict the detection 
of a planet in that interval. This conjecture attracted but little 
: on till after the discovery of Uran istance was 
found to harmonize in a remarkable manner with Kepler's 
t — ress ‘course regarded 
é 
