ON THREE BALLOON ASCENTS IN 1865 AND 1866. 



387 



These mean values at the mean height were laid down on a diagram ; all these 

 points were joined, and a curved line was drawn through, or near them, so 

 that the areas of the space between the original and the adopted lines on one 

 side were equal to those of the spaces on the other side. The curve thus 

 formed was assumed to he the curve of temperature freed from local 

 disturbance, and that it was assumed that the deviations of the original cui've 

 indicated the places and the amount of disturbance. 



The next step was reading from these curves the temperature at every 

 100 feet, and in this way the next Tables were formed. 



The niunbers in the first column show the height in feet, beginning from 

 the ground and increasing upwards ; the numbers in the second column show 

 the interval of time in ascending to the highest point ; the notes in the third 

 column show the circumstances of the observations ; the numbers in the fourth 

 and fifth columns, the observations and the approximate true temperatures of 

 the air, and those in the next column the difference between the two 

 preceding columns, or the most probable effect of local disturbing causes. 



The next group of columns are arranged similarly for the descent, and the 

 other groups, on May 29, for the second ascent and second descent. 



Table III.- — Showing the Temperature of the Air, as read off the curve 

 drawn through the observed temperatures, and as read off the curve of 

 most probable normal temperatures, called adopted temperatures, and the 

 calculated amount of disturbance from the assumed law of decrease of 

 temperature. 



TWENXT-SIXTH AsCENT. 



The temperature of the air was the lowest on the ground, and increased, 

 with elevation, to the height of 2000 feet, the highest point attained ; and on 

 the descent it decreased with decrease of elevation, and was the lowest on 

 reaching the ground. 



2c2 



