ON NINE BALLOON ASCENTS IN 1863 AND 1864. 



271 



Table III. (continued.) 

 Twentieth Ascent. 



June 20. — The temperature of the air on the ground before starting was 

 061°, which declined very gradually to 4100 feet, where it was 51°. On 

 descending it increased gradually tiU 2700 feet was reached, it then being 

 54°. On ascending to 4200 feet, the temperature fell to 49|°. On de- 

 scending for the last time, it increased to 61° at 2000 feet, and to 64|° 

 on the ground : this was about one hour before sun.set, showing in the last 

 2000 feet an increase of temperature of 3°, thus showing that the usual 

 law holds good to this time, but apparently with far less energy, as on 

 ascending the decrease of temperature in the same space was three times as 

 large, or 9°. 



June 27 — On this occasion the temperature was 63° on the ground, 

 gradually decreasing to 1000 feet, where it was nearly 57°, then declined 1|° in 

 200 feet, then gradually to 2600 feet, when a comparatively warmer current 

 was met with, the temperatiu-e declining only lg° in the following 900 feet, 



