246 Resisting Medium. 
Art. III.—Remarks upon some of the probable effects of a Resist- 
ing Medium ; by Tuomas H. Perry, Prof. Maths. U.S. N. 
Ir is a somewhat common opinion, that the resisting medium 
believed to ocenpy the planetary spaces, must eventually destroy 
the motions of the solar system. This conclusion does not seem 
to me to be justified by the state of the facts at present known: 
and, although it may not be easy to demonstrate the absolute im- 
possibility of such an effect, the admirable provisions for the con- 
tinuance of the present arrangement of the heavenly bodies, 
which science has already elicited, ought to be considered, at 
least until contrary probabilities are shown to exist, presumptive 
indications of its future permanence. 
The final effects of a resisting medium must depend upon its 
extent and mode of distribution. The facts from which its exist- 
ence is deduced, do not apprise us whether it is, or is not, limited 
to a comparatively small distance fromm the sun ; nor whether it is 
diffused continuously from this luminary to the remotest limits of 
his system, or is disposed about him in concentric zones, separat 
by intermediate spaces, incapable of impeding ponderable bodies. 
It is not a legitimate inference that the medium by which comets 
are retarded is essential to the transmission of light, and therefore 
the visibility of the remotest stars; which would in that case be 
relevant fact, has no necessary connection with the subject. 
Were it proved that the ether is in its extent as unlimited as 
space, and that its elasticity is no where counterbalanced by any 
kind of attraction, it would indeed follow that its effects, how- 
ever inappreciable and indefinitely slight in any finite period, 
must become sensible, when augmented by the increments of 
time in the same degree indefinitely great ; and that the planets, 
as has been often asserted, must, in the lapse of a sufficient series 
of ages, fall to the sun. 
But while we have, in known facts, no evidence that the ether 
is thus universally diffused, we are led by analogy and the favor- 
ite theories of the age, to presume the contrary. If, as every Cl” 
cumstance that has any bearing upon the subject conspires 10 
evince, all the ponderous globes in the universe, once perva® 
Space as attenuated nebulz, surely it must require great elasticity 
and expansion of the ethereal matter to fill the vacuum formed by 
