462. REPORT—1862. 
An inspection of this Table shows that the largest numbers are those 
situated at the bottom, and the smallest at the top of each column in all states 
of the sky, and therefore that the decline of temperature in equal spaces was 
largest in that space next the earth, and gradually less with increase of ele- 
vation. 
The numbers in the last column of the Table show the average value at 
each 100 feet, the one in cloudy states of the sky, and the other in partially 
clear states, with the number of experiments upon which each result is based. 
FRoM THESE RESULTS THE DECLINE OF TEMPERATURE 
When the Sky was Cloudy 
For the first 300 feet was ...... 0°-5 for every 100 feet. 
From 300 feet to 3400 feet was 0°-4 
a et00 4, * S000 &,,; 20S 
2? 9 
39 3) 
Therefore in cloudy states of the sky the temperature of the air decreases 
nearly uniformly with the height above the surface of the earth nearly up to 
the cloud. 
When the Sky was partially Cloudy. 
in the*first S: 2. 100 feet there was a decline of 0°-9 
From 100 feet to 300 % Pe Pe 0°-8 for each 100 feet. 
” 300 ” 500 ” ”? ” 0°7 ” 
» 200 5, 900 ” 3 ” 0°-6 
» 900 ,, 1800 9 3 » 0°-5 
” 1800 ” 2900 ” ” ” 0°°4 ” 
” 2900 ” 5000 ” ” ” 0°3 ” 
The decline of temperature near the earth with a partially clear sky is 
nearly double of that with a cloudy sky; at elevations above 4000 feet, the 
changes for 100 feet seem to be the same in both states of the sky. 
In some cases, as on July 30, the decline of temperature in the first 100 
feet was as large as 1°1. 
From these results we may conclude that in a cloudy state of the sky the 
decline of temperature is nearly uniform up to the clouds; that with a clear 
sky the greatest change is near the earth, being a decline of 1° in less than 
100 feet, gradually decreasing, as in the general law indicated in the preceding 
Section, till it requires a space of 300 feet at the height of 5000 feet for a 
change of 1° of temperature. These results lead to the same conclusion as 
before, viz. that the theory of gradation of 1° of temperature for every 
300 feet of elevation must be abandoned. As regards the law indicated by 
all these experiments, it is far more natural and consistent, than that a uni- 
form rate of decrease could be received as a physical law up even to moderate 
elevations. 
§ 6. Vartarron or tHE HyGRoMErRIC CONDITION OF THE ATR WITH ELEyATION. 
All the adopted readings of the temperature of the dew-point in Section 4 
were laid down on diagrams of a large scale, and their points were joined; and 
as it was evident that there were strata of moist air, and that the changes do 
not follow any regular decrease as in the case of the temperature of the air, 
it was therefore not considered prudent to adopt any curve with the view of 
obtaining normal results, but to use the projected curve as simply found by 
joining the points as stated above. ‘From the readings at every 1000 feet of 
