x THE STARRY HEAVENS 399 
That each planet and satellite did form 
originally a ring we still have evidence in the 
wonderful and beautiful rings of Saturn, 
which, however, in all probability will eventu- 
ally form spherical satellites like the rest. 
Thus then our Earth was originally a part 
of the Sun, to which again it is destined one 
day to return. M. Plateau has shown experi- 
mentally that by rotating a globe of oil in a 
mixture of water and spirit having the same 
density this process may be actually repeated 
in miniature. 
This brilliant, and yet simple, hypothesis 
is consistent with, and explains many other 
circumstances connected with the position, 
magnitude, and movements of the Planets 
and their satellites. 
The Planets, for instance, lie more or less 
in the same plane, they revolve round the 
Sun and rotate on their own axis in the same 
direction —a series of coincidences which can- 
not be accidental, and for which the theory 
would account. Again the rate of cooling 
would of course follow the size; a small body 
cools more rapidly than a large one. The 
