they
attempt to delineate the features of a body 50,000,000 or 100,000,000
miles away through such a disturbing medium as our atmosphere. Even on
such a subject as the canals of Mars doubts may still be felt. That
certain markings to which Schiaparelli gave the name of canals exist,
few will question. But it may be questioned whether these markings are
the fine, sharp, uniform lines found on Schiaparelli's map and
delineated in Lowell's beautiful book. It is certainly curious that
Barnard at Mount Hamilton, with the most powerful instrument and under
the most favorable circumstances, does not see these markings as canals.

I can only mention among the problems of the spectroscope the elegant
and remarkable solution of the mystery surrounding the rings of Saturn,
which has been effected by Keeler at Allegheny. That these rings could
not be solid has long been a conclusion of the laws of mechanics, but
Keeler was the first to show that they really consist of separate
particles, because the inner portions revolve more rapidly than the
outer.

The question of the atmosphere of Mars has also received an important
advance by the work of Campbell at Mount Hamilton. Although it is not
proved that Mars has no atmosphere, for the existence of some
atmosphere can scarcely be doubted, yet the Mount Hamilton astronomer
seems to have shown, with great conclusiveness, that it is so rare as
not to produce any sensible absorption of the solar rays.

I have left an important subject for the close. It belongs entirely to
the older astronomy, and it is one with which I am glad to say this
observatory is expected to especially concern itself. I refer to the
question of the variation of latitudes, that singular phenomenon
scarcely suspected ten years ago, but brought out by observations in
Germany during the past eight years, and reduced to law with such
brilliant success by our own Chandler. The north pole is not a fixed
point on the earth's surface, but moves around in rather an irregular
way. True, the motion is small; a circle of sixty feet in diameter will
include the pole in its widest range. This is a very small matter so
far as the interests of daily life are concerned; but it is very
important to the astronomer. It is not simply a motion of the pole of
the earth, but a wobbling of the solid earth itself. No one knows what
conclusions of importance to our race may yet follow from a study of
the stupendous forces necessary to produ