BAROMETRICAL MEASUREMENT OF HEIGHTS. 395 



In Table III., for A, with the argument i", take c', which, in this case, is always 

 positive ; then, remembenng that the values of c and c' are given in units of the 

 fifth decimal, we have, 



V -\- c -\- c' = log h in toises, 



V -\- c -{■ c' -\- 0.28982 =^ log h in metres, 



V -\- c ■]- c' -\- 0.80584 = log h in English feet. 



Example 1. 



L. station B = 329.013 Pans lines; T =+ 15.88 R.; ^ = + 15.96 R.; <j!) = 45 32. 

 IT. station B' = 268.215 Paris lines ; T' = -f" 8.40 R.; t = -(- 7.92 R. 



t -\- t' = 23.88 R. 



log B = 2.bV12'i — 10 X 15.88 = 2.51563 

 log B == 2.42848 — 10 x 8.4 = 2.42764 



u = 0.08799 



log?< = 8.94443 



A = 3.99982 



V = 2.94425 

 c = — 00002 

 c' =r + 0.00012 



log h = 2.94435 



h = 879.74 toises. 



Example 2. 



L. station B = 763.15 millimetres ; T = t =^ 25.3 Cent. = 20.24 R. ; (f> = 21. 

 U. station B' = 600.95 millimetres ; T' = t' ^ 21.3 Cent. = 17.04 R. 



i.-\-t> = 37.28 R. 



log B = 9.88261 — 10 X 



log B' =: 9.77884 — 10 x 



log h = 3.83492 for English feet. 

 h — 1069.3 toises = 2084.0 metres ^ 6837.9 English feet. 



D 55 



