48 A. Hinrichs on the Density, Rotation, and Age of the Planets. 
Il. The Laws of Density and Rotation.” 
the entire planetary | 
to the mode of this development. be 
Helmholtz,” and others. Yet the minimum in density exhibited 
by Saturn, and above all the singular motion of the satellites of : 
Uranus, appearing to be entirely at variance with the very fum — 
damental principle of the theory, seem to have bronght these — 
views into disrepute; Brewster even pronounces them to Dé — 
“the dull and ‘dangerous heresy of the age.” ‘The theory of 3 
Laplace seems to have been abandoned without trying to recon — 
cile it with Uranus—which planet was yet unknown at the time ~ 
Plateau’s” researches on the equilibrium of fluids did but revive — 
this theory for a moment.”* ou 
It will easily be seen that our estimate of the planetary ages — 
as based upon the resistance of ether and seen in the cont . 
tion of the several systems, fully agrees with the hypothesis & 
* This part of the present paper was in part communicated at the meeting of 
Scandinavian Naturalists at Copenhagen, 1860; see Forhandlinger, 1860, p. ih 
noes scarcely to be remarked that we only opposed the absolute stability — 
as ge: ead Laplace. i 
. rie des Himmels, 1755. “ 
» Exposition du systéme du monde, 2d éd., Paris 1799, Liv. v, Chap. vi- 
Astronomie Populaire, ii, 7, Paris and Leipzic, 1855, at a 
Naturlerens mechaniske Deel; a text book of Natural Philosophy, used 
the U niversity and Polytechnic School of Copenhagen. ee 
J i 9. 
22 
ie ; 
ee ee ed eee tak ba eT Ree er | art eae 
a Memoirs of the Life and Discoveries of Sir Tsanc Newton, London, 1855, ii,181- 3 
Mém. de PA xelles, vol. xvi, 1843, § 19-27. a 
: is que suivent les forces attractives pore pe et a 
8Ses Planetaires, nous avons vu se produire, en peti Oe 
maga mene de la pluspart des phénoménes de eaigunioe relatifs 
Corps célestes, (§ 27). uy Gs 
* It affords me great pleasure to find an able advocate of this theory in | 
K ; see this Journal, 1860, [2], xxx, 160-181. 
