little things, called "corpuscles," play an important part in what
is going on among the stars. Whether this be true or not, it is
certain that there do exist in the universe emanations of some
sort, producing visible effects, the investigation of which the
nineteenth century has had to bequeath to the twentieth.

For the purpose of the navigator, the direction of the magnetic
needle is invariable in any one place, for months and even years;
but when exact scientific observations on it are made, it is found
subject to numerous slight changes. The most regular of these
consists in a daily change of its direction. It moves one way from
morning until noon, and then, late in the afternoon and during the
night, turns back again to its original pointing. The laws of this
change have been carefully studied from observations, which show
that it is least at the equator and larger as we go north into
middle latitudes; but no explanation of it resting on an
indisputable basis has ever been offered.

Besides these regular changes, there are others of a very
irregular character. Every now and then the changes in the
direction of the magnet are wider and more rapid than those which
occur regularly every day. The needle may move back and forth in a
way so fitful as to show the action of some unusual exciting
cause. Such movements of the needle are commonly seen when there
is a brilliant aurora. This connection shows that a magnetic storm
and an aurora must be due to the same or some connected causes.

Those of us who are acquainted with astronomical matters know that
the number of spots on the sun goes through a regular cycle of
change, having a period of eleven years and one or two months.