ON EIGHT BALLOON ASCENTS IN 1862. 469 
Taste VII. (continued.) 
Hygrometrical results. 
Ascending. Descending. 
Height, in feet, 
above the mean Tempe Degree Tempe De 
- . _ * e 
level of the sea. |B ap Circum-|rature of rake of gaits Circum- abe of] Eustace 2 
times, | St@nces.|the dew- vapour humi Pi ities stances, |the dew- ce es humi- 
point. dity. ? point. Pours dity. 
September 8.| 2 | o | in. Y o | in 
4000 q Hliactoua} 48°6| -343| 86 |S 5 [aona! 49:1| +349] 96 
3000 Bae . 5r8| °385) 85 oF 
zooo fA) SB | 559| 447| 83 SEs 
1000 te, a 2 595] 509] 82 |h ae 
° + 615) °546| 77 S 
5000 7 : 33°5} 192] 44 || Ae 45°O| 299] 53 
qocoo | dg. SE STE | OF Ne 482) °338) 89 
3000 5B Se Bar ee 0, 38 46°0| -311] 75 
2000 re on eee Sy 3 540] 418 
1000 on wee 5° 58°90 “482 
° Y - a) _ > 
wn 3 
38°-9 between 4300 and 4700 feet, and declined to 362° from 5600 feet to 
6800 feet. The relative humidity increased with slight variations from 67 
on leaving the earth to 100 at 6800 feet in a cumulus cloud; on passing out 
of the cloud, the dew-point declined quickly to 303° at 7600 feet, then uni- 
formly to 263° at 9800 feet: the relative humidity decreased to 69 at 7600 
feet, and increased to 81 at 10,000 feet; in the dew-point a slight increase 
then took place to 27° at 10,800 feet, and then a decrease to 192° at 12,600 
feet. The dew-point increased to 223° at 13,000 feet, and the humidity to 
91 at this elevation. The dew-point was 103° at 16,800 feet, and the hu- 
midity was 77. A rapid decrease of the dew-point then took place to —21° 
at 19,200 feet, and then as rapid an increase to —7° at 19,500 feet and to —3° 
at 20,100 feet: the humidity declined to 18 at 19,200 feet, and increased to 
36 at 19,500 feet, and to 50 at 20,100 feet. 
Above this point the temperature of the dew-point rapidly declined: at 
24,000 feet no dew was deposited on Regnault’s Hygrometer, and at higher 
points still it must have been less than —50°. 
In the descent there were no marked irregularities till the balloon was 
within 8000 feet of the earth, when the dew-point increased and decreased 
two or three times in the next 4000 feet, after which it declined gradually to 
the earth. 
The variations in the amount of moisture in the air on this occasion were 
few and to small amounts after passing out of the cloud in which the air was 
saturated. About 1800 feet a dry stratum of air was passed, and after 2000 
feet the amount of vapour became smaller, and was exceedingly small in 
amount at the higher elevations. 
September 8.—The humidity in this ascent increased from the earth to the 
clouds with very little variation, but on passing above them the decrease was 
very great; the two latter results are not used in the formation of the next 
Table. 
