Milford chronicle., 1889-08-09
The Agricultural Experiment Sta.
ton.
MErEoRoLoeY.

The temperature and moisture of the at
mosphere, the amount of rainfall and sun
shine, the direction and force of winds, ant
other meteorological phenomena exercise
most important influence upon animal an'
vegetable life, and systematic observation
and records of meteorological conditions con
stitute an essential part of experiments
work in agriculture.
The Station is furnished with the apparatu
necessary for observing air temperature, al
pressure, humidity, soil temperatures a
various depths water temperature, rain and
snow fall, solar and terrestrial radiation
and wind-direction. The meteorological
instructments have been obtained from Mr.
Henry ]. Green, of New York, the well
known maker of scientific apparatus for thu
United States Signal Service, the Smithso
nian Institute, the Geological Survey, ect.
ect., ect',
The barometer is Green's form of Fortin'
Instrument, the advantage is, that leve
ofthe mercury in the cistern can always be
broght to the zero point of the scale by turn
ing a screw which raises or lowers the kiC
skin bottom of the cistern. The scale il
divided into tentls of an inch, and, with the
vernier, reads to hundredths of an inch.
By the relative humidity the atm osphers
is meant the ratio of the amount of moisture
in the air to the amount required to saturate
it. This is determined by means ofthe psy-
chrometer or wet and dry build thermometer
The GOODNESS of the surface of evaporating
water increases with the rate of evaporation
consequently with the dryness of the air.
When the bulb of the thermometer is mois-
perature Of the surface of evaporation is
given by this Thermometer, and the tempera-
ture of the air is observed with another Their
mometer. The bulb of the thermometer to
observe the temperature of evaporation is
kept wet by surrounding it with thin mus
lin cover to which wick immersed in water
is attached. Tables have been prepared
marking the determination of the dew. peinti
and the relative humidity of the air from
the reading of the wet and dry bulb Their
mometers very simple. With his instru-
ment the occurrence Of frost during the
night may be predicted with reasonable
certainty early in the evening.
The mean temperature of the day is the
sum twenty four hourly readings divided by
twenty -four, but years of experience show
that the mean derived from fewer readings
differs inappreciably from that obtained by
making hourly readings The range of tenn
perature in twentY-four hours is given by
the readings of self registering maxim UNI
and minimum thermometers which mark
the highest and lowest temperatures, res
pectively, of the day. The former is a mer-
curial thermometer in the bore of which
just above the bulb is a construction that
allows the mercury to pass through in pulses
as it expands with increase of temperature,
and prevents its return when the temperature
is lowered. After an observation is made
the column is restored BY centrifugal force
by revolving the thermometer about
a pin passing through the upper part of the
metallic plate to which it is fastened. When
adjusted the thermometer rests in nearly
horizontal position, the bulb lower than the
stem. The minimum is an alcoholic Their
in which there is a small black
glass rod or boat. As the alcohol descends it
carries with it the glass float, but when it
rises it passes the float without disturbing it
When adjusted it rests in nearly horizontal
position, the bulb a little lower than the
stem. By raising the bulb after an observa-
lion the float is made to return to the top of
The column.
The psychrometer, maximum and minimum
thermometers are exposed in a shelter care
July constructed so as to avoid the effects of
iirect solar radiation and ofheat reflected
md rsdiated from surrounding objects, and
1t the same time, to insure full aud free ven
ilatiou
The amount Of solar and terrestrial radia-
ion is given by the readings of selfre gister-
ug maximum and minimum thermometers;
he former a mercurial thermometer with
bulb; enclosed in a Dubbed tube
,arefully exhausted of air and moisture, the
after naked bulb alcoholic thermometer
With its stem enclosed in a glass jacket.
The station has FIVE soil thermometers o
he pattern devised for the New York Ex-
,eriment Station. They are one inch, two
inches, six inches, twelve inches, twenty |
our inches long, respectively, and when
'lanted in the soil give its temperature at
hese debths.
The rain-gauge is the same as is used by |
he L. S. signal service and consists essen
tally of basis or receiver with a small |
rihce in the bottom leading into a carefully |
brass cylinder. The sectional
rea of the receiver is ten times that of the |
rass cylinder, so as TO assist in making
an inch rainfall making ten
inches in the cylinder.
Arrangements have been made with the
.hief Signal officer of the army, by which,
q return for monthly reports of observations
lade here, the station will receive copy
the Monthly Weather Review ard of all
ie other publications of the department.