The Sun.
London, England, 1862-08-02 00:00:00

/ 6 0.-- 4

PRICE.....- ..4d.
STAMPED

deg. ; at 3,700 feet it was•sl deg. ; continued at this
reading nearly till the height of 4,500 feet was
reached at sh. 4m. ; varied between 48 deg. and 50
deg. till the height of 5,700 feet was reached ; it
decreased from 48 deg. to 433 deg. between sh. 31m.
and sh. 38m., the height at the latter time being
6,100 feet. At the height of 7,350 feet the tempe-
rature was 41 deg., being 27 deg. lower than on
the surface of the ground; after this the tempera-
ture rose gradually as the balloon approached the
' earth, and was 47 deg. at 6h. 20w., 50 deg. at 61].
24m., and 68 deg. on reaching the ground.
The temperatures of the dew point, or that tem- 1
perature at which the moisture in the air, in the 1
invisible shape of vapour, is deposited as water upon
the objects cooled down to this temperature, were
successively as follows :—ln the gardens of the
1 Crystal Palace this deposit of water took place when
the temperature of the bulb of the hygrometer was
reduced by the action of ether to 50 deg.; at the
height of 1,300 ft. the bulb was bedewed at 43 deg.;
between 3,000 ft. and 4,500 ft. at 40 deg.; then up
to 6,000 ft. at temperatures gradually decreasing at
about 7,300 ft. to a little below 32 deg., and it after-
wards increased to 47 deg. on reaching the surface
of the earth. .When air is saturated with moisture,
as in a wetting fog, the temperatures both of the
air and dew point are the same. On this oe-anion
on the earth the latter temperature was 18 ueg. be-
low the former, and at the highest elevation was 9
deg., so that the air was nowhere saturated. 'Prom
a knowledge of the temperature of the dew point
we know the amount of Inter then present in a
certain amount of air. This amounted in the grounds
of the Crystal Palace to 4 grains in a cubic foot ; at
1,300 ft. high to 3 grains; at 5,000 ft- to about 24
grains; and at 7,300 ft. there were about 2 grains in
a cubic foot of air.
As the amount of aqueous vapour in the air neces-
sarily decreases with the temperature, the changes
of the hygrometric condition of the air at different
elevations may be better understood by speaking of
the relative humidity of the atmosphere, by consi-
dering air saturated with moisture as represented
by 103, and air without moisture by O.
The humidity of the air thus expressed was on
the surface of the ground 50, showing an unusual
degree of dryness. It increased as we left the earth
to 63 at 3,000 feet, to 66 at 4,000 feet, and 70 at
7,300 feet, and the air gradually became less humid
on approaching the earth. At no point, therefore,
was complete saturation met with, as before noticed.
The weight of a cubic foot of air varied from 526
grains on the ground to 429 grains at the greatest
height reached.
Similar and simultaneous observations were taken
at the Royal Observatory, Greenwich, from
which we learn that the temperature of the air on
the surface of the ground varied from 67 deg. to 68
deg. ; that of the dew point from 49 deg. to 51
deg, ; that there were about four grains of water in
a cubic foot of air ; the degree of humidity was
about 50, and the weight of a cubic foot of air was
526 grains ; therefore, the differences at the high
elevations from these values are duo to the elevation
alone.