son, Becquerel, and Roentgen, have
demonstrated the existence of objects so minute that they find their
way among and between the atoms of matter as rain-drops do among the
buildings of a city. More wonderful yet, it seems likely, although it
has not been demonstrated, that these 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. Now, the curious
fact is, when the number and violence of magnetic storms are recorded
and compared, it is found that they correspond to the spots on the sun,
and go through the same period of eleven years. The conclusion seems
almost inevitable: magnetic storms are due to some emanation sent out
by the sun, which arises from the same cause that produces the spots.
This emanation does not go on incessantly, but only in an occasional
way, as storms follow each other on t