by mathematics and the spectroscope--The question of their
origin and ultimate fate--Dr. Dick's idea of their
habitability--Swedenborg's curious description of the
appearance of the rings from Saturn--Is Saturn a globe of
vapor, or of dust?--The nine satellites and "Roche's
limit"--The play of spectacular shadows in the Saturnian
system--Uranus and Neptune--Is there a yet undiscovered
planet greater than Jupiter?


CHAPTER VIII

_THE MOON, CHILD OF THE EARTH AND THE SUN_ 212

The moon a favorite subject for intellectual speculation--Its
nearness to the earth graphically illustrated--Ideas of the
ancients--Galileo's discoveries--What first raised a serious
question as to its habitability--Singularity of the moon's
motions--Appearance of its surface to the naked eye and with
the telescope--The "seas" and the wonderful mountains and
craters--A terrible abyss described--Tycho's mysterious
rays--Difference between lunar and terrestrial
volcanoes--Mountain-ringed valleys--Gigantic cracks in the
lunar globe--Slight force of gravity of the moon and some
interesting deductions--The moon a world of giantism--What
kind of atmospheric gases can the moon contain--The question
of water and of former oceans--The great volcanic cataclysm
in the moon's history--Evidence of volcanic and other
changes now occurring--Is there vegetation on the
moon?--Lunar day and night--The earth as seen from the