ide by the orbit of Jupiter it was thought at one
time that no planet revolved. Modern research has shown that this region
is tenanted, not by one planet, but by hundreds. The discovery of these
planets is a charge which has been undertaken by various diligent
astronomers of the present day, while the discussion of their movements
affords labour to other men of science. We shall find something to learn
from the study of these tiny bodies, and especially from another small
planet called Eros, which lies nearer to the earth than the limit above
indicated. A chapter will be devoted to these objects.

But we do not propose to enter deeply into the mere statistics of the
planetary system at present. Were such our intention, the tables at the
end of the volume would show that ample materials are available.
Astronomers have taken an inventory of each of the planets. They have
measured their distances, the shapes of their orbits and the positions
of those orbits, their times of revolution, and, in the case of all the
larger planets, their sizes and their weights. Such results are of
interest for many purposes. It is, however, the more general features of
the science which at present claim our attention.

Let us, in conclusion, note one or two important truths with reference
to our planetary system. We have seen that all the planets revolve in
nearly circular paths around the sun. We have now to add another fact
possessing much significance. Each of the planets pursues its path in
the same direction. It thus happens that one such body may overtake
another, but it can never happen that two planets pass by each other as
do the trains on adjacent lines of railway. We shall subsequently find
that the whole welfare of our system, nay, its continuous existence, is
dependent upon this remarkable uniformity taken in conjunction with
other features of the system.

Such is our solar system; a mighty organised group of planets
circulating under the control of the sun, and completely isolated from
all external interference. No star, no constellation, has any
appreciable influence on our solar system. We constitute a little island
group, separated from the nearest stars by the most amazing distances.
It may be that as the other stars are suns, so they too may have systems
of planets circulating around them; but of this we know nothing. Of the
stars we can only say that they appear to us as points of light, and any
planets they may possess