pposing it to be finally established, it would follow
that the decennial period, which we measure by our magnetic
instrument, is, in fact, a solar period, manifested to us, also, by
the alternately increasing and decreasing frequency and magnitude of
observations on the surface of the solar disc. May we not have in
these phenomena the indication of a cycle, or period of _secular
change in the magnetism of the sun_, affecting visibly his gaseous
atmosphere or photosphere, and sensibly modifying the magnetic
influence which he exercises on the surface of our earth?"--American
Journal of Science, new series, vol. xiv. p. 438.

I think it may fairly be inferred, that although these spots do not
occasion the "cold spells" and "hot spells," and other transient
peculiarities, they do materially affect the _mean_ temperature of the
year, and exert an obvious influence when at their maxima; and there is a
tendency to an increase of the heat and dryness of summer, and the
severity of winter, at the periods named, in our excessive climate, and a
well-established connection between the spots and magnetic disturbances
and variations.

Popular opinion has ever attributed to the moon a controlling effect upon
the changes of the weather. If it be dry, a storm is expected _when the
moon changes_; or if it be wet, dry weather. Such popular opinions are
usually entitled to respect, and founded in truth. But every attempt to
verify _this opinion_, by careful observation and registration, has
failed. Weather-tables and lunar phases, compared for nearly one hundred
years, show four hundred and ninety-one new or full moons attended by a
change of the weather, and five hundred and nine without. The celebrated
Olbers, after _fifty years of careful observation_ and comparison, decided
against it. So did the more celebrated Arago, at a more recent
date--summing up the result of his observations by saying--"Whatever the
progress of the sciences, never will observers, who are trustworthy and
careful of their reputation, venture to foretell the state of the
weather." Still, the moon may influence the weather, though she may not
effect changes at her syzygies or quadratures, and this subject should not
be too summarily dismissed. That the moon can not effect changes at the
periods named seems philosophically obvious. She changes, for the _whole
earth_, within the period of twenty-four hours; yet, how varie