calling it the Lord. These wicked spirits
are separated from the rest, and are not tolerated by them. 'The
nocturnal light,' say the spirits, 'comes from the immense ring which at
a distance encircles that earth, and from the moons which are called the
satellites of Saturn.' And again, being questioned further 'concerning
the great ring which appears from our earth to rise above the horizon of
that planet, and to vary its situations, they said that it does not
appear to them as a ring, but only as a snow-white substance in heaven
in various directions.' Unfortunately for our faith in the veracity of
these spirits, it is certain that the moons of Saturn cannot give nearly
so much light as ours, while the rings are much more effective as
darkeners than as illuminators. One can readily calculate the apparent
size of each of the moons as seen from Saturn, and thence show that the
eight discs of the moons together are larger than our moon's disc in
about the proportion of forty-five to eight. So that if they were all
shining as brightly as our full moon and all full at the same time,
their combined light would exceed hers in that degree. But they are not
illuminated as our moon is. They are illuminated by the same remote sun
which illuminates Saturn, while our moon is illuminated by a sun giving
her as much light as we ourselves receive. Our moon then is illuminated
ninety times more brightly than the moons of Saturn, and as her disc is
less than all theirs together, not as one to ninety, but as sixteen to
ninety, it follows that all the Saturnian moons, if full at the same
time, would reflect to Saturn one-sixteenth part of the light which we
receive from the full moon.[29] As regards the rings of Saturn, nothing
can be more certain than that they tend much more to deprive Saturn of
light then to make up by reflection for the small amount of light which
Saturn receives directly from the sun. The part of the ring which lies
between the planet and the sun casts a black shadow upon Saturn, this
shadow sometimes covering an extent of surface many times exceeding the
entire surface of our earth. The shadow thus thrown upon the planet
creeps slowly, first one way, then another, northwards and southwards
over the illuminated hemisphere of the planet (as pictured in the 13th
plate of my treatise on Saturn), requiring for its passage from the
arctic to the antarctic regions and back again to the arctic regions of
the planet, a period