occur in greatest numbers in periods of about eleven years apart, and
astronomers and geologists agree that periods of rainy and dry seasons
seem to correspond with the sun-spot periods.

When the greatest number of spots are visible on the sun, scientists
agree that the climatic conditions on the earth are normal and even.
When there are fewest spots on the sun we have extreme temperature and
sudden changes. When we say that astronomers and geologists agree on
this point, we must also admit that some astronomers are not quite
satisfied that the fact has been proved.

The only fact that has been actually proved to everybody's satisfaction
is that, during the time when the most spots are visible on the sun,
there are always more magnetic storms and displays of the aurora
borealis.

A magnetic storm is a disturbance of the magnetic field which surrounds
the earth; its presence is shown by a disturbance of the needle of the
compass, and it often interferes with the electrical currents, making it
difficult and sometimes impossible to use the telegraph-wires.

The aurora borealis is a wonderful light seen in the sky in high
latitudes, and less frequently in other parts of the world--except
during the activity of the sun-spots.

It appears as irregular patches and dancing columns of light which flame
across the sky. Red, white, pale green--these shafts are now dim, now
bright, seeming to throb and pulse as they glow and pale. As you watch
them they change their form, and, from being pillars of fire, change to
masses of glowing color.

A flash-light dancing across the sky gives you some, though a very poor
notion, of an aurora. The aurora has thousands of such flashes of light,
changing form and color as you watch them--filmy shafts of light, coming
you know not whence.

The spots on the sun are described as being dark patches which are
visible on the bright surface of the sun. They often appear in groups,
and frequently the larger spots will break up into smaller ones. They
are great depressions or holes in the surface of the sun, and are
supposed to be formed by descending currents of gases.

Sun-spots are generally found in the neighborhood of the sun's equator,
and last from a few hours to a few months.

The presence of these spots has enabled scientists to prove that the
sun, like the earth, revolves on its axis.

The last period of activity for sun-spots was in 1893, and, according to
the eleven-year theory