indeed fall on our little plum, but those that do are the source of
all life, whether animal or vegetable. If the sun's rays were cut off
from us, we should die at once. Even the coal we use to keep us warm is
but sun's heat stored up ages ago, when the luxuriant tropical
vegetation sprang up in the warmth and then fell down and was buried in
the earth. At night we are still enjoying the benefit of the sun's
rays--that is, of those which are retained by our atmosphere; for if
none remained even the very air itself would freeze, and by the next
morning not one inhabitant would be left alive to tell the awful tale.
Yet all this life and growth and heat we receive on the whole earth is
but one part in two thousand two hundred millions of parts that go out
in all directions into space. It has been calculated that the heat which
falls on to all the planets together cannot be more than one part in one
hundred millions and the other millions of parts seem to us to be simply
wasted.

For untold ages the sun has been pouring out this prodigal profusion of
glory, and as we know that this cannot go on without some sort of
compensation, we want to understand what keeps up the fires in the sun.
It is true that the sun is so enormous that he might go on burning for a
very long time without burning right away; but, then, even if he is
huge, his expenditure is also huge. If he had been made of solid coal he
would have been all used up in about six thousand years, burning at the
pace he does. Now, we know that the ancient Egyptians kept careful note
of the heavenly bodies, and if the sun were really burning away he must
have been very much larger in their time; but we have no record of this;
on the contrary, all records of the sun even to five thousand years ago
show that he was much the same as at present. It is evident that we must
search elsewhere for an explanation. It has been suggested that his
furnace is supplied by the number of meteors that fall into him. Meteors
are small bodies of the same materials as the planets, and may be
likened to the dust of the solar system. It is not difficult to
calculate the amount of matter he would require on this assumption to
keep him going, and the amount required is so great as to make it
practically impossible that this is the source of his supply. We have
seen that all matter influences all other matter, and the quantity of
meteoric stuff that would be required to support the sun's expendit