The barometer falls for a southerly wind, including from southeast by south to the westward, for wet weather, for stronger wind, or for more than one of these changes, except on a few occasions, when moderate wind, with rain or snow, comes from the northward.
A fall, with a south wind, precedes rain.
A sudden and considerable fall, with the wind due west, presages a violent storm from the north or northwest, during which the glass will rise to its former height.
A steady and considerable fall of the barometer during an east wind indicates a shift of wind to the southward, unless a heavy fall of snow or rain immediately follows.
A falling barometer, with the wind at north, brings bad weather; in summer rain and gales; in spring snows and frosts.
If, after a storm of wind and rain, the barometer remains steady at the point to which it had fallen, severe weather may follow without a change in the wind. But on the rising of the barometer a change of wind may be looked for.
The following rhymes are familiar to most sailors:
When the glass falls low, Look out for a blow.
First rise after low, Portends a stronger blow.
When the glass is high, Let all your kites fly.
Long foretold—long last; Short notice—soon past.
The following notes may be relied on for forecasting the weather:
Red sky in the morning, wind or rain, and often both.
Very clear atmosphere near the horizon is a sign of more wind and often rain.
Here follow some old sailors' jingles which I heard when a boy in the forecastle:
When rain comes before the wind, Sheets and halyards you must mind; When wind comes before the rain, Hoist your topsails up again.
Evening red and morning gray Are sure signs of a fine day; But evening gray and morning red, Makes a sailor shake his head.
Amateurs while on a cruise should frequently look at the barometer and take notes of its height and enter them in the log.
The action of the aneroid barometer depends on the effect produced by the pressure of the atmosphere on a circular metallic chamber partially exhausted of air and hermetically sealed. This kind of barometer is liable to changes on account of its mechanism getting out of order, and it should be often compared with a mercurial barometer, which from its cumbersomeness cannot be conveniently carried in a small craft. Aneroid barometers of excellent quality, and of about the size of an ordinary watch, are offered for sale at a reasonable price, and a cruise should not be undertaken without one.