E. W. Evans on the Action of Oil-Wells. 159 
Divipine at 
Srarion, 0, 6, 12, 18h. { 1, 7, 13, 19h. | 2, 8, 14, 20h. 
Boy ee] ae Be me ff, 
ps Per ct. |} Per ct. | Per ct. | Perct. | Per ct. | Perct. | Per ct. | Per ct. | Per ct, 
|Girard College, | 45°92 | 41°32 | 12°76 | 31:3 | 49°5 | 192 | 13°8 | 63-2 | 23-0 
St. Helena, 25°97 | 42°96 | 31°07 | 15°83) 467 | 375 56 | 566 | 878 
The percentages of the calculated values correspond very 
neatly with the means of the earliest Girard College and St. 
Helena values. 
| Calculate M imi 
vais ae Percentage. | hime Limits. 
{ 
|| 79-49 37°6 35°95 56 45°92 
eae ag Sore Hong 40°8 42°14 403 63°2 
Bye es eee 4°} 21°6 21°91 12°76 87°8 
It may be inferred from this comparison that the rotation ele- 
ment of daily heat is least affected, and the solar element most 
ected, by extraneous causes (of which moisture is probably 
the chief); that the first division gives the best, and the third 
division the poorest, results; that the proportion of thermometric 
variation which is attributable to rotation is between “4 and ‘5 o 
the average total daily variation, and that the most difficult ele- 
ment to determine satisfactorily is S., which is modified by man 
local disturbing influences, such as the nature of the soil, amount 
of vapor, clouds, altitude of the sun, &c. 
Philadelphia, May, 1864. 
Arr. XIII.—On the Action of Oil- Wells ; by Prof. E. W. Evans, 
Marietta College. 
THE phenomena exhibited by oil-wells suggest various prob- 
lems, the discussion of which may be of scientific as well as 
Practical interest. The facts on which the following remarks 
less liable to be carried away by running water. Prof. KE. B. 
n, in an article | aadreer: in this Journal, 
common to fin 
; but whatever may be their origin 
t horizontal 
