Hut and Thermal Springs. 14& 



perature ot the aimospherc, or of the siirt'atc of the earth, to 

 decrease 1° R. (= iJ°.25 F.) lor every additional vi I'ccl in 

 height, then we shall have 



EF =(<"+ 1° — r_.i°)?j_ (l_.r)K 



but further, 



sm a 

 E F = B E cotang a 



= BH 



cotang a 



ijin a 



Substituting the above values of B H and E F, we find 



, , , cotang a 



(1 — x) n = m X " — 



sin a 



and from this we obtain 



1 



m cotang « 

 nsina 



nsina 



m cotang a + ra sin a 

 We have, therefore, 



m n sin a 



BH = 



EF = n 



m cotang a + n sin a 

 71^ sin a 



m cotang a+ n sin a 

 m n cotang a 



m cotang n + ra sin a 



BV- 



TO n cotang a 



cos a {in cotang a + n sin n) 

 Example : let , 



a = 30° n 

 n = 115 feet 

 m ■=. Gil feet 



then wc shall have 



X = 0°.047 

 BH =31.05 feet 

 EF = 109.62 feet 

 B F = 12C.C2 feet 



Thus, if in plains an increase of temperature of S'.SS be found 

 at a depth of 115 feet, the same increase will not be foimd till a 

 depth of r/v'6.G2 feel, in a vertical direction from the summit of a 



