reason of its decreased volume. So, too, the absence of spots,
and a more powerful influence from the solar rays, may gradually carry
the machinery further north in summer, and further south in winter, and
thus make the _seasons extreme_ without seriously disturbing the mean of
the year. And both these may occur in a more marked degree over our
intense magnetic area than in Europe. I am satisfied that they do so
occur. That the partial failure of the sun's rays limits the transit of
the machinery, and the volume of the trades during the latter half of the
decade, and extends the transit and increases the volume during the first
half, producing an occasional severe summer drought and severe winter, in
the warmest portion of the decade. And that the variations correspond with
the difference in the character and number of the spots in different
decades, and hence the longer and shorter periods.

Turning to the tables of Dr. Webster, we find that a general tendency to
extreme seasons does seem to exist from the 6th to the 10th year of every
decade, and especially of every alternate decade. The periods of 1707-8,
1728, 1737 and 1739, 1749-50, 1758-9, 1779-80, 1798-9, are those in which
the tendency was seen most decided. These tables are very general. The
thermometer was not perfected till about 1700, and did not get into
general use before 1750. There were very few meteorological registers
kept, or accessible to Dr. Webster. Hence he was obliged to resort to such
other sources of information as were open to him, and such statements as
he found are not always entirely reliable. The oldest inhabitant is apt to
express himself very strongly respecting present extremes, and fail
somewhat in his recollection of those which have past. Still his tables
afford general and obvious evidence of the regularity of those periodic
conditions.

+---------------------------------------------------------+
|A. D.| Summer. | Winter. |
|-----|-------------------------|-------------------------|
| 1701| hot and dry | .... |
| 1702| hot and dry | .... |
| 1703| .... | .... |
| 1704| dry Europe | .... |
| 1705| .... | .... |
| 1706| hot, dry Europe | .... |
| 1707| very hot | ....