The Iowa plain dealer. [volume] (New Oregon, Howard County, Iowa) 1867-1895, 1890-03-20
THE BAROMETER.
How Changes Of weather Are Indicated
Errors About the Inst1ament.

How Changes OF weather Are Indicated
Errors About the Instramsnt.
Certain people have attempted to es-
tablish rules BY which the coming state
Of the weather may be predicted from
the height Of the mercury in the baron
eter; and we accordingly ind the words
..rain,' .'chapgeable," sfsir." "frost,"
etc., engraved on the scale attached to
common domestic barometsPs. % II,
when tho mercury stands at the height
marked by these Words the weather 10
always subject to tho vicissitudes ex-
pressed by them. These marks ard,
however, entitled to no attention, and
1t is only surprising to ind their uss
continued in tho present times, whom
knowledge Is % widely difused. Two
barometers ono nesr The level OF the
Hudson river, and the other on the top
Of Trinity steeple, will differ by half an
inch, the latter being always half an
inch lower than the former. II the
words, therefore, engraved upon the
plates arc to be relied OH, similar
changes Of weather could never happen
at these two situations. But what 10
even moro absurd, such q scale would
inform us that the weather Ut the foot
Of high building must always be DIFF
ferent from the weather at the top Of IL.
Changes Of weather are indicated, not
BY the actual hight Of the mercury, but
BY It's change Of height. One Of the
most general, though not absolutely in
variable rules 10 that where the mercury
Is very low, and therefore the atmos-
phere very light high winds and storms
may be expected. The following rules
may generally be relied on, at least to .
certain extent:
l. Generally the rising Of the mercury
indicates the approach Of fair weather;
the falling Of it shows the approach Of
foul weather.
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.
8. Whatever change Of weather sud.
denly follows, a change In the barometer
may be expected to last but short
time. Thus, IL fair weather follow i'm
mediately the rise Of the mercury, there
will be very little OF it; and in the same
way, II foul weather follow the fall OF
the mercury. 1t will last but short
time.
4. II fair weather continue for several
days, during which the mercury contin.
ually falls, long continuance Of foul
weather will probably ensue; and again,
II foul weather continue for several
days, while the mercury continually
rises, o long succession Of fair weathe,
will probably succeed.
| 5. A fuctuating and unsettled state Of
the mercurial column indicates change
able weather.
The domestic barometer would b.
como much more useful instrument Il
instead OF the words usually engraved
on the plate, short list Of the bes,
established rules, such ~ the above, 40
companied 1t, which might be either en-
graved on the plate or printed on card
II would be right, however, to express,
the rules only with that degree Of prob
ability which observation Of past phe
nomena has justified. There IL no rule re
ipecting these effects which will holt
good. In explanation let 1t be know
that when the mercury falls this actor
shows only that the atmosphere has Be
come lighter. Now, inasmuch ~ mois
air is lighter than dry air, It Il assures
that when the atmosphere changes from
heavier to lighter condition 1t also be
comes more moist; and 70 it general,
does, but this Is not always the case. =
st. Louis Globe Democrat.