ON EIGHT BALLOON ASCENTS IN 1862. 463 
elevation the next Table was formed ; other readings were taken at angular 
intermediate points, and these are included in the remarks following the 
Table. The numbers under the heading of “Tension of Vapour” are formed 
by using “ Regnault’s Tables,” and the degree of humidity in the next column 
has been calculated by using the observed temperature of the air correspond- 
ing to the observed temperature of the dew-point. 
Taste VII.—Showing the Variation of the Hygrometric condition of the 
Air at every 1000 feet of Height. 
Humidity of the Air. 
Ascending, 
Height, in feet, 
above the mean Tempe- - | Degree 
level of the sea. Between arauine tee ae Fiatie = 
wha orce 0: a 
times. | *#nces- wer "| vapour. cm 
La Sa ga 
Yabo SER esas 
25000 Ea | aa bas 
24.000 BSesle'ssi\a's> 
23000 25s 4a5=l4% 
22.000 pers jp° 
21000 ° in. 
dened , Er, 1670| ‘o89| 48 
19000 g 3 24°1| “130) 54 
aed a it 23'8 128| 62 
17000 iF 3 ee a 
16000 A 3 22°8 ig 
15000 "4 < 235) 1426) 7 
14000 £ 23°9| "128| 78 
13000 | 24-0). AS) oe 
12000 a 23°8| 128) 92 
11000 a 23°3; "125| 89 
10000 + ae al Sioned 
gooo a aot) AES ine ZS 
8000 g 27°9| "152| 84 
7000 g mj | 30°0| ‘167} 78 
6000 ae a5 32°0] 181} 90 
5000 ws) 32°0 "181 76 
ae 340] "196| 65 
3000 a“ 39°6| °243) 73 
2000 23 44°7| ‘296) 75 
cpa SS | 497| °357| 77 
% 55°°| °433] 79 
July 17.—At the earth’s surface the dew-point was 55°, which seemed to 
decrease gradually to the height of about 4000 feet, the ‘relative humidity 
decreasing from 79 to 65 within the same space; on entering a cloud the 
rate of the decrease of the dew-point was checked, and for a space of 3000 feet 
was almost constant, differing but little from 32°, whilst the relative humi- 
dity increased to 91 at 5800 feet. On leaving the cloud at 8000 feet high, 
and between that and 9600 feet, both the dew-point and the relative humidity 
decreased quickly, the former to 17°-9 and the latter to 65. From 9600 feet 
to 11,500 feet, whilst the temperature of the air remained at 26°, the dew- 
point increased to 24° 8, and the relative humidity to 95, closely approaching 
to saturation. From the height of 12,000 feet to 19,000 feet, the amount of 
water in the air was almost constant, the dew-point undergoing scarcely any 
