The Providence news. (Providence [R.I.]) 1891-1906, 1896-03-18

the tube, but when II reaches point
where the pressure OF the air which Is
trying TO get up INTO this vacuum equals
the weight OF the column OF mercury be-
low the vacuum, a delicate balance is Sc
cured, and every change in the pressure
of the air is thereafter shown by the ris-
ing or falling OF the mercury in the tube.
Of course, at the same time that these
changes occur more or less OF the mercury
remains in the cup at the DO tom, ana Tor
purposes of record this is ether regulated
10 a fixed point with screw, which
raises or lowers q leather bottom to the
cup, or a sliding scale Is used in taking
the measurements, but for general use
this is important.
The aneroid barometer works upon the
same principle, but In place of the column
of mercury there - used in II either one
or a series of flexible meal disks, from
which the air Is exhausted. The pressure
of the air which tries TO enter these disks
Is met with the counter-pressure OF
spring or weighed lever, and the move
ment which takes place is transmitted TO
a hand which revolves about dial
These machines are made in sizes rang
ing from that of watch 10 machines
with 10 or IL inch dials.
The men who study the barometer the
closest are ship masters. The weather
bureau men keep record OF its doings,
and watch its movements closely enough,
devices and reports from all parts OF the
country upon which to base their prog
nostications of the weather. The sailor
man has nothing else except his knowl-
edge OF the direction and force OF the
wind, the look of the sky, ana the feeling
of the air. "Weather" TO the sailor man
means wind. however, and he does't care
much whether he is going to have rain or
snow with the wind or not. still, he can
tell about these, too.
In the face of every barometer Is hand
or little sliding gauge which can be set
to the point where the barometer stands
at the time OF any observation. In the
summer the observer must watch the vari-
ations more closely than in winter, for
tney are, as a rule, of less amount, and
therefore mean more than in the winter.
The nearer the tropics the closer, too,
must we observe the barometer.
"In these latitudes", said Captain Charles
B. Parsons, who sailed for 70 years the
West Indies, "the winds which bring
wind or snow with them generally come
from the east. With a northeast wind
blowing a fall of two-tenths of an inch in
the mercury means usually that the wind
Will be stronger from the same direction.
IL the wind is from the east and the
barometer goes down little, 1t means
that the wind is going TO the south'ard.
When the wind blows from the southeast
and the glass is falling, the wind is go-
ing to the westward, and the rapidity OF
the change In the glass indicates clearly
the rapidity with which the change will
take place, and the severity OF the wind
which Is coimng. a slow and STEADY fali
means that the wind is becoming more
fixed and that the weather will be steady
for some time.
"When the wind is at the westward,
watch for rise ip the glass. Just cs
long as the mercury stays steady the
wind will blow, but it will moderate
with the change. The highest readings
are usually with the north or northeaster-
ly winds. In summer time look out for
squalls IL the glass shows drop OF 2-10
of an inch, or even less, in short time. "
The farmer is another man who is
deeply interested in knowing what sort
OF weather he is going to have. The
smoke from his Kitchen chimney has bet n
his barometer for many centuries. III 1t
rises straight up he looks for fine weather
and il it sinks and trails along the ground
he says the air is heavy, and he looks for
rain. Then If he Is smear" down-easter
or "close" Jerseyman he gets out the
garden tools and tells the men they cam
work in the kitchen garden when it
rams too hard to work in the field.
Many farmers in late years have bought
barometers and learned the meanings OF
their changes, and reaped great profit
from their use The storm glass which
is sold for trifie in the shops, mounted
usually in the connection with ther-
mometer, Is cheap form OF the barom-
eter. 1t consists of a tube Of glass of from
six to ten inches in length in which
cloudy solution of camphor IL held in
suspension in alcohol. With each change
in the pressure. of the air the camphor
solution rises or falls in the tube. going
up when the barometer falls. and down
with rise in the barometer. IL is
marked "Fair" at the bottom. "Change"
at the center, aud "Stormy" at the top,
and its markings are just as deceptive as
those of the regular barometer; but
careful observer, nothing the changes
which take place il the posi- ion of the
camphor, could come pretty near to tell
ing what the weather was going TO be.
Such glasses sell for as littl, as 20 cents.
Mercurial barometers sell for from 70 TO
800, and aneroid barometers from s3 TO
$50. A new device for demonstrating
minute changes I'm the atmosphere was
shown recently at the exhibition OF the
Berlin Physical Society. 1t consisted OF
glass whose neck communicated with
a horizontal glass tube, the central por-
tion of which was slightly bent down
ward. In this tube was mobile globule
of colored petroleum, and this moved
backward or forward with each change
in the outward pressure. 1t showed re-
suits which indicated that 1t was 150
times more sensitive than the mercurial