270 



eeport — 1864. 



the earth, it did not decline at all till after 300 feet had been passed, after 

 which it decreased pretty gradually to 33° when 4300 feet was reached ; a 

 warm cm-rent was then entered, and the temperature increased till 7500 feet 

 was attained, being of the same temperatui-e as has been experienced at 

 1500 feet high, viz. 40°, then decreased to 34° at 8800 feet, and then in- 

 creased slowly to 36|° at 11,000 feet, a temperature which had been ex- 

 perienced at the height of 2170 feet in ascending. 



On descending the temperature increased about 5° in the first 1000 feet ; 

 remained at about that temperature till within 7000 feet of the earth, then 

 gradually decreased to 40° at 3000 feet, remained at about this point tiU 

 1500 feet of the earth, and then increased to nearly 46° on the ground. The 

 observed temperatures on this day are so remarkable that no adopted tem- 

 peratures have been made. 



June 13. — The temperature of the air on the groimd before starting was 

 62°, declining with increase of elevation till 3000 feet was reached, where 

 it was 51 1°; on descending the temperature was found to be 54° at 2300 

 feet ; the balloon then reascendcd, the tomperatiu'c declining gradually to 

 3100 feet, then began to increase, being 48|° at 3450 feet, but declined to 

 47° by passing upwards to 3540 feet ; on again descending it increased evenly 

 till at 2700 feet, it being there 51°, and remained about the same for 200 feet ; 

 on reascending the temperature scarcely differed from 51° till 3000 feet was 

 gained, when a sudden decrease of 2° oecui-red in 35 feet ; then began our 

 final descent, the temperature remaining the same for 400 feet, then increased 

 to 51|° by 2000 feet, and to 53°-2 at ISOOfeet, below which there was scarcely 

 any change till the earth was reached. 



This fact of no change in the temperatur-e of the air within 1800 feet of the 

 earth at the time of sunset was very remarkable, for it indicated that if such 

 be a law, the law of decrease of temperature with increase of elevation may 

 be reversed at night for some distance from the earth. 



