1882.] 
Correspondence. 
45 
laws or principles of motion. Why did not that same attractive 
force which caused the big tides when the Moon was so much 
nearer the earth prevent the moon from receding ? What has 
been the force which has raised the Moon 240,000 miles from 
the Earth ? We have been told that the attractive force of the 
Sun originally lifted the Moon out of the Earth ; but as, accord- 
ing to Prof. Ball, the Earth is eighty times as heavy as the 
Moon, the Sun should certainly have exercised as great an 
attractive force upon the one as upon the other, and therefore 
no further separation should have taken place. They might both 
have dropped into the Sun before now, but, if the attraction of 
two bodies varies inversely as the cube of their distance, it was 
impossible for them to move asunder. The theory that the Sun’s 
attraction may have been the cause of the Moon’s receding 
motion is, moreover, utterly inconsistent with the fact that, in 
one portion of her orbit, she is 240,000 miles more distant from 
the Sun than is the Earth. Instead of the Moon being attracted 
towards the Sun, in one-half of her orbit she is going in the 
reverse direction, and does so to the extent of 480.000 miles. 
The same attractive force cannot be supposed to produce opposite 
mechanical effects. 
Prof. Ball believes that “ every body in the universe is capable 
of producing, and actually does produce, tides in every other 
body.” The Earth may therefore have arisen from the Sun, as 
the Moon has arisen from the Earth. If the Moon is the child of 
the Earth, reasoning from analogy, the Earth may be supposed 
to be the child of the Sun. Such is my conclusion. Children 
are in the habit of growing. I believe that the whole of the 
planetary bodies have been derived from the Sun by a progressive 
development. The evolution of species is part of a great scheme 
of creation in which the whole solar system is concerned, and 
“ natural selection ” is one of many methods by which organic 
life is brought into harmony with the Earth’s perpetual constitu- 
tional change. My conclusions are founded, not upon mathe- 
matical reasoning based upon a fidtion as to the power of 
gravitation, but upon an immense range of circumstantial evi- 
dence, supported by diredt observation. Biologists and geologists 
both inform us that the history of the Earth has been one of 
progressive development. The fadts of Astronomy teach the 
same lesson. Thus there is a relation between the sizes of the 
planets and their distances from the Sun ; suggesting that, if 
they have risen from the Sun, as Prof. Ball says the Moon has 
risen from the Earth, they have grown as they have receded. 
There is a relation between the number of satellites of a planet 
and its distance from the Sun ; again suggesting a progressive 
development. There is a relation between the rotary motion of 
a planet and its distance from the Sun, the rotary velocity in- 
creasing with the distance. Instead, therefore, of the Earth’s 
motion of rotation having diminished, as alleged by Prof. Ball, 
