straight line, a row of second-magnitude stars about equally spaced
and of the most striking beauty. In the course of time, however, the
two right-hand stars, Mintaka and Alnilam (how fine are these Arabic
star names!) will approach each other and form a naked-eye double, but
the third, Alnita, will drift away eastward, so that the ``Belt'' will
no longer exist.

For one more example, let us go to the southern hemisphere, whose most
celebrated constellation, the ``Southern Cross,'' has found a place in
all modern literatures, although it has no claim to consideration on
account of association with ancient legends. This most attractive
asterism, which has never ceased to fascinate the imagination of
Christendom since it was first devoutly described by the early
explorers of the South, is but a passing collocation of brilliant
stars. Yet even in its transfigurations it has been for hundreds of
centuries, and will continue to be for hundreds of centuries to come,
a most striking object in the sky. Our figures show its appearance in
three successive phases: first, as it was fifty thousand years ago
(viewed from the earth's present location); second, as it is in our
day; and, third, as it will be an equal time in the future. The
nearness of these bright stars to one another -- the length of the
longer beam of the ``Cross'' is only six degrees -- makes this group
very noticeable, whatever the arrangement of its components may be.
The largest star, at the base of the ``Cross,'' is of the first
magnitude, two of the others are of the second magnitude, and the
fourth is of the third. Other stars, not represented in the figures,
increase the effect of a celestial blazonry, although they do not help
the resemblance to a cross.

But since the motion of the solar system itself will, in the course of