3J2 On Hypsometrical Measurements. [No. 4j. 



(Substituting these values iu the formula, we have 



P (?)(&'" *)■( 0.379 /^ 

 Log '^ == 'T U — a. C,and— 



F L(l + ^) ( -v/pp 7 ) 



B (?)£' — h)C 2M. L(l + «rf) a 0.379/) 



Log- = — J 1 —— [ . 



B' L(l+a*) (. (y) r ^/j3 b' J 



a -f- o- 



Replacing a, by , and introducing the values of 2M, L, 



2 



and r, in the factor within the parenthesis, this equation becomes 



B ig) Qt - h) 



Log — = — x 



B' L (1 + at,) 



(g) 20888733 — 52436 (1 + at) 0.1895 p'. a + a! 



20888733 (g) </~8B 



and without any sensible error, — 



B (g) {h'— h) (• 397.37 — at (a + a). 0.1895 p 



B {g) {k'— h) C 397.37 — at (a + a). U.isy^ p ) 



Log-- [ 



B' L (1 + at) ( 398.37 */~SW J 



GO (*' — *) (397.37 — at) f (a + a). 75.49/ 



= < 1 — 



398.37 (1 + a* ) L I (397.37 -«0^13 B' 



Hence, we have for the approximate height, 



398.37 {1 -{-at) 1 l 



h'— £=(logB— logB') % L x — X 



397.37 — ^, (^) « + a' 75.49^ 



ViTb 7 397.37-^ 

 and for the true height — 



H' — H = 7/ — £ + ■ . 



r — li r — h 



It remains to adapt these formula for tabular computation ; and 

 for the sake of brevity let us write 



398.37 



A = . L (1 + at), 



397.37 — at 



75.49 



and C = . »', 



397.37 — at 



