ON NINE BALLOON ASCENTS IN 1863 AND 186 L 



Table VII. (continued.) 

 Fifteenth Ascent. 



289 



September 29. — The temperature of the dew-point decreased from 44° ou 

 the ground, or 490 feet above the sea, to 42|° at 1000 feet above the sea, 

 where mist was prevalent, and the degree of humidity increased from 86 to 89. 



On passing out of the mist at 3000 feet the humidity declined from 87 to 

 58 at 8000 feet ; here there were dense clouds both above and below ; at 

 9000 feet the degree of humidity was 71. 



There were faint gleams of the sun at 10,000 feet, and the difference between 

 the temperature of the air and dew-point was 22\°, the degree of humidity 

 being 36, showing a decrease of no less than 35 in a difference of 1000 feet 

 of elevation ; at 11,000 feet it was drier still, the temperatures of the air and 

 dew-point being 16°-9 and — 8°- 6 respectively, or a difference of 25°-o, and the 

 degree of humidity 31 ; at 13,000 feet the difference had decreased to 4°-4 

 and the humidity increased to 81 ; at 15,000 feet it was 12°-0, and the hu- 

 midity had decreased to 54 ; the balloon continued to ascend, but the humi- 

 dity is unknown above the last-mentioned height, tiU on descending to 13,000 

 feet it was 54, and the difference between the temperatiu-es of the air and 

 dew-point was 13°-9 ; at 10,000 feet the air again became very dry, the two 

 temperatures being 22°-9 and — 10°-2 respectively, showing a difference of 

 33°-l and a humidity of 21 ; the air then gradually became less dry till 

 5000 feet, when the difference was ll°-9 and the humidity 56; after this 

 the difference increased in a small amount, and then decreased to 20°-2 at 

 2000 feet, where the humidity was 45. 



1864, 



