2. In sultry weather the fall of the mercury indicates coming thunder. In
winter, the rise of the mercury indicates frost. In frost, its fall
indicates thaw; and its rise indicates snow.
3. Whatever change of weather suddenly follows a change in the barometer,
may be expected to last but a short time. Thus, if fair weather follow
immediately the rise of the mercury, there will be very little of it; and,
in the same way if foul weather follow the fall of the mercury, it will
last but a short time.
4. If fair weather continue for several days, during which the mercury
continually falls, a long continuance of foul weather will probably ensue;
and again, if foul weather continue for several days, while the mercury
continually rises, it long succession of fair weather will probably
succeed.
5. A fluctuating and unsettled state in the mercurial column indicates
changeable weather.
The domestic barometer would become a much more useful instrument, if,
instead of the words usually engraved on the plate, a short list of the
best established rules, such as the above, accompanied it, which might be
either engraved on the plate, or printed on a card. It would be right,
however, to express the rules only with that degree of probability which
observation of past phenomena has justified.
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