1878. ] 303 (Chase. 
dications point to the simultaneous, or nearly simultaneous, initiation of 
numerous planetary centres, and it is very doubtful if either of the two- 
planet belts, except, perhaps, that of Neptune and Uranus, will be long re- 
garded as having been ‘‘ thrown off’’ by the mere increase of centrifugal 
velocity. 
At the very outset of my own investigations,* I was careful to limit my 
acceptance of the nebuar hypothesis to the qualified exposition of its origi- 
nator, as stated by Sir John Herschel: ‘‘ Neither is there any variety of 
aspect which nebule offer, which stands at allin contradiction to this view. 
Even though we should feel ourselves compelled to reject the idea of a gase- 
ous or vaporous ‘nebulous matter,’ it loses little or none of its force. Sub- 
sidence, and the central aggregation consequent on subsidence, may go on 
quite as well among a multitude of discrete bodies, under the influence of 
mutual attraction, and feeble or partially opposing projectile motions, as 
among the particles of a gaseous fluid.’’ + 
It matters not whether there is such a thing as a luminiferous ether, or 
whether the hypothesis of such an entity is merely a convenient assump- 
tion for the co-ordination of results which are due to the action of forces 
such as would exist in such a medium. The proper study of the forces, and 
of their mathematical consequences, is the great thing to be sought, and 
the numerous accordances which I have already found, show how prolific 
such studies may become. Those accordances, as it seems to me, are 
already sufficient to establish the Herschelian hypothesis as a true theory, 
beyond the reach of all possible controversy. That the elastic, or quasi- 
elastic, forces, which are continually operating throughout the solar system, 
should extend the harmonic laws to the satellites, as well as to the planets 
and to the spectral lines, is a necessary consequence of the simplicity and 
unity of design which underlie the manifold phenomena of the universe. 
In the case of our own moon, as we have only two terms, Earth’s semi- 
diameter and Moon’s orbital major-axis, the harmonic equation is indeter- 
minate ; its direct solution is, therefore, impossible. I have elsewhere, 
however, called attention to the fact that Earth is central, in the belt which 
is bounded by the secular perihelion of Mercury and the secular aphelion 
of Mars, and this fact, together with the nearly synchronous rotation of 
all the planets in the belt, may be regarded as indications of common forces, 
such as would be likely to lead to common harmonies. The sixth and 
seventh divisors of the Mars series represent, respectively, the ratio of 
Earth’s semi-diameter to Moon’s major-axis, and the ratio of Earth’s axial 
rotation to its orbital revolution, viz.: 
3d,— d, = 122. 120.5331 = Moon’s major-axis. 
3 dg — d, = 365. 365.2564 = Karth’s year. 
The harmonic series, of which Mars and its satellites form a part, seems 
to have been established before the ring of greatest nebular condensation— 
the ring of which Earth was the centre—was broken up. In the solar 
* Phil. Mag., April, 1876. 
+ Loe. cit. 
in 
ll Il 
(ie 
