, 1910-02-02

At Estete Sally's Fancy 3 lines Of rain
were measured on Monday morning.
The first half of the month just closed
was marked by continuous strong winds from
the northeast or east-northeast. These were
followed by ten day. of mostly calm weather,
during the latter five Of which che low
clouds. with scarcely ATTY perceptlble wind,
shifted their course round from east through
south and west to north, from which point it
blew hard on the afternoon OF Wednesday
the 26th, shifting during the night to north
east and by Saturday round to about east,
dropping at the same time to a light breeze.
On Sunday the 30th it went back to north
east and increased in strength, but by
Monday morning had given place to a calm,
with a gentle drift of the lower clouds
from about east.
The most noteworthy feature, however, of
the weather of the above mentioned period
was The temperature, records Of which for
the week from the 25th to the Dist are given
below. The observations we're made with
Centigrade (CeIsius) thermometers, but
have been given also IN the sca.e Of Reau-
mur and Fahrenheit to facilitate their eX-
animation by readers more accustomed to
one or other Of those scales than to the
centigrade. 1t is believed that the figures
will be found accurate to the nearest tenth
OF q degree.
1t will be seen that the first and second
columns in each case give the records OF
the wet and dry bulb thermometers respec-
lively, while the third column gives the low
est temperature for the night. All the OBJ
seryations We're taken at eight o'clock in the
morning.
For readers not familiar with the use of
wet and dry bulb thermometers a few words
Of explanation are desirable before we call
attention to some figures Of special interest
III the table.
The atmosphere, besides the nitro
gen and oxygen which chiefly make
il up, contains small proportions of
other gases and a considerable proper
ton Of water gas, or vapour of'water, as it
is commonly called, which vapour is con-
tinually varying in amount. Iu other words
the air l. mo- OF less dry or damp. Ii dry
it is very greedy OF moisture, and evaporation
from wet surfaces is everywhere rapid, but if
damp it sucks up the wet quite leisurely orin
other words evaporation is slow. That eyapo-
ration lowers the temperature OF the surface
from which it takes place is a well known fact;
hence it is that we use porous goblets to cool
our drinking WatGI; the actlOh OF which
is that Il part OF the water in the goblet
oozes out through The pores in the clay and
keeps the outside damp, and the evaporation
therefrom lowers the temperature of the sur
face, consequently by degrees lowers the
temperature Of the whole vessel and its con
tents.
1t may be readily understood that stu
dents OF the weather, besides learning the
weight Of the air from time to time from the
barometer and its degree Of heat from the
thermometer, would wish also to know its
condition as to moisture, and in this inquiry
they make use of the varying rates of eva
poration above noticed. Two Thermometers
of the same construction are placed side by
side and the bulb Of one of them IS wrap
ped in a single linen covering, connected by
some thick, soft and open cotton threads
with water in a cup near by, The threads,
acting like II lamp wick, draw up the wator
and keep the linen covering around the bulb
wet, and the temperature of the bulb is con
sequently lowered, the mercury contracts and
the reading is low6fed. How much it will
be lowered depends Oh the dryness or damp
ness of the air, and to measure how much it
il lowered we have the other thermometer