On the Precession of the Equinoses. 139 
Arr. XII.—On the Precession of the Equinozes. 
To the Editor of the American Journal of Science. 
Sik, - 
In No. 2. Vol. VI], of the Journal of Science, you publish- 
ed an article upon the Precession of the Equinoxes. The 
writer of that article mentioned some objections to the com- 
mon theory upon that subject which he considered insuper- 
able. He also suggested the idea that our system revolves 
about a “ distant centre” in what he calls the ‘ Orbis Mun- 
dorum,”’ and that the Precession of the Equinoxes is owing 
to the advance of the system in this orbit, while the earth re- 
volves in the Ecliptic. I refer the reader to that article, 
for further particulars. 1 beg permission to say a few words 
relative to the writer’s objections to the old theory, and also 
to mention some objections that arise in my mind to his 
‘recently discovered” theory. 
1. He says “ that different astronomers with equal con- 
fidence, form different conclusions relative to the size and 
shape”’ of the Equatorial ring, “‘and until these are posi- 
tively known, no rational or conclusive demonstration can 
be made of the nature and power of its attraction.” It has 
been satisfactorily proved by the Trigonometrical Surveys, 
and by the vibration of the pendulum that the Equatorial 
diameter of the earth, exceeds the Polar at least thirty-four 
miles, and consequently it is proved that a protuberant ring 
of matter surrounds the earth seventeen miles in thickness 
extending north and south of the equator, until it gradually 
becomes nothing 
On the supposition that the mean density of the ring’ 
equals the mean density of the earth, (considered as : 
sphere surrounded by this ring,) Newton proved that the 
quantity of matter in the earth : quantity of matter in the. 
ring: 529000 : 461. He also calculated that the momen- 
tum of the ring spread out in its natural place, is equal to 
the momentum of a ring of moons surrounding the equator, 
containing 2 of the same quantity of matter. It has like- 
wise been calculated that the influence of the sun upon the 
equatorial ring to turn it about its centre is equal to the in- 
fluence it would exert upon a ring of moons placed at the 
