y 
42 D. Trowbridge on the Nebular Hypothesis. 
the remaining rings alone equals the ;1,th of the mass of Sat 
urn. Even now the period of Saturn’s rotation exceeds that of — 
eculiarities. We have already shown that according to Prof. 
eirce’s deductions a planetary-ring might exist for a great 
length of time just within the orbit of Jupiter; the same influ’ 
Venus; and each of these latter bodies would lend their influ: | 
ence, and would thus influence the Mercurial-ring. These in- — 
terior rings (as we will call them, being interior to the Aster 
oids,) being thus sustained for a great length of time, would 
loose much of their heat, and thus become condensed consider: 
ably perhaps, as have the rings of Saturn, When such rin 
broke up and assumed the spheroidal form, they would be mu 
less likely to abandon satellite rings, than those planets whose 
rarity was greater. e have already shown that the meat 
density of those planets nearer the sun should be found to 
greater than that of the outer planets; we now refer to the il 
fluence above mentioned to account for the sudden increase of 
mean density within the orbit of Jupiter; for evidently the 
mean density of a planet formed from a ring considerably com 
densed, would be greater than one formed from a ring less 80 
r a crust would form around one approximately as soon ‘ 
around the other. The period of rotation of such planets w 
of Mars and Jupiter, seems to confirm the view which we ba¥ 
given of their formation, in a preceding part of this paper. 
we divide 360° by 80, we find an average of one Asteroid. 
* Cosmos, iv, 422, Bohn’s ed. | 
