xg8 
The Birth and Evolution 
[April 
Mars, 0*698 ; Venus, 0*940 ; Jupiter, 0*243 ; Saturn, 0*140; 
Uranus, 0*178 ; Neptune, 0*238. It is difficult to account 
for laws of density ; we entertain a general idea, we see if 
the results correspond, and we are satisfied when we reason 
logically. Density must depend on the relations of the pro- 
jecting masses, and on the pressure to which the projected 
mass is exposed at its ultimate position. In the case of the 
two central planets the relation was less complicated. The 
mass of the secondary systems is projected between its 
central part and the solar influence — here repulsive, there 
attractive. We seek at first the imaginary density, the point 
of gravitation ; from this we infer the density of the concen- 
trations. The exterior system is projected by the smaller 
mass between the larger mass and the Sun. 
We had the density of the primary point of gravitation 
equal to that of the Sun, equal 1. Matter projected by 
Saturn arrives here between a mass 3*347 times greater and 
the Sun, and thus becomes 3*347 times more dense than 1 
(the Sun) : but Saturn has an elongation of 1*025 > matter 
arrives consequently with a retardation of 1*025 1 density 
so becomes — 
— 3*2 more than that of the Sun. The greater, then, the 
elongations of the concentrations, so much more they are 
pressed against the more powerful limiting bodies, so much 
denser they become ; so are more dense than the Sun. 
Comparing these densities with those of observation, the 
density of the Earth is 1-1*012 less, or that of the Sun 
0*255 °f that of the Earth; Jupiter and Saturn agree 
with observation ; Venus and Mercury are slightly less than 
the figures of observation. A more considerable difference 
exists with regard to Mars. The exterior system is pro- 
jected by the larger mass, by the recalling distant attraction 
of the Sun and the smaller less dense mass of the central 
aphelion (Saturn). It is the central mass which projects ; 
the density would so be equal to 1, to that of the Sun ; but 
as the projecting mass has an elongation of 1*05 towards 
the Sun, the propelled mass arrives with a 1*05 2 = 1*07 times 
greater velocity, density becomes 1*107 more than that of 
3*347 - 3*347 
1025 2 1*05’ 
Venus ... 3*2x1*107x1*05. 
Earth ... 3*2x1*22. 
Mars ... . 
1*107 x 1*05 
Mercury 3*2 x i*22 2 . 
