68 
The Birth and Evolution 
[February, 
planetary mass at i-68oth of that of the sun ; it amounts to 
the so-manyth part, as the sun is its own radii distant from 
the farther limit of that zone which is designated as “ sepa- 
rating contracts.” 
The body exists by opposition, for by it density exists, 
which like all qualities is comparative. Suppose the whole 
planetary mass at this distance of 680 solar radii from the 
centre of gravity of the sun, without regard for the present 
that it must also extend away from the sun or this zone. 
Imagine the sun dissolved, reaching there, and both bodies 
of like density. Those two nebulse with incipient nuclei, 
those vapour atmospheres, touch each other, flowing in one. 
There is no reason that their mean density should differ; 
their distance is proportional to their masses, divided by the 
square of distances, if we call distance the distance of the 
surface of the one from the centre of gravity of the other. 
The difference of density can only result from the variety of 
motions, and the development of this variety of motions we 
have to find. 
The radii of these equally dense nebulse with incipient 
nucleus (atom) are to each other as the cubic roots of their 
masses, — consequently the radius of the planetary mass is 
to that of the sun as 1 to 878, or roundly 8*8. Motion there 
must be ; it depends on the relation of masses, and the 
original existence of motion decides the relation of masses : 
these are correlates ; we have only to find what is and how 
it is. 
This planetary mass revolves round the sun, because 
motion develops itself into regular rotation. With which 
velocity does it move ? with the same mean one with which 
a planet would move there — about 54 Paris feet in the 
second. Translation is consequent on rotation ; the con- 
verted sides repulse, the averted ones attract each other, as 
I proved. A point under the equator of this planet would 
then move in its rotation through about 54,000 Paris feet in 
a second, if such planet were of equal density with the sun 
moving at a distance of 680 solar radii. The rotatory adtion 
cannot be more rapid, only slower than the translatory one, 
than the quantity of motion obtained at all, and there is no 
reason that it should be less, as the densities of both 
bodies are equal, the distances their radii, the sun the larger 
one. 
The velocity of motion is a gradual result of opposing 
masses. A planet thought possible to glide on the sur- 
face of the adtual sun would move through 1,400,000 Paris 
feet in a second ; consequently on the surface of that. 
