390 



REPORT 1864. 



Table VII. (continued.) 

 Sixteenth Ascent. 



October 9. — The difference between the temperatures of the air and dew- 

 point on the ground was 10|°, their respective readings being 54i° and 44° ; 

 and this difference varied but little tiU 7310 feet was reached, at which height 

 the temperatures were 30° and 18° respectively. On descending to 2330 feet 

 the temperature of the air was 42°, and that of the dew-poiut 35^°, the dif- 

 ference being 6^°. On reascending the difference was found to be rather 

 larger, but on descending agaia it decreased to 6^° at 2270 feet, where mist 

 was prevalent, and it decreased to 2°-7 at 1500 feet, the two temperatures 

 being 44°-8 and 42°-l respectively. On ascending to 3300 feet, the air 

 became suddenly drier, continued of the same degree of humidity to 4000 feet, 

 above which there was less and less humidity with increase of elevation till 

 the height of 8000 feet was reached, when it became too dark to read the 

 instruments. 



