

BAROMETRICAL TABLES. xll 



most probable value, taking into account the recently determined relation 

 between the liter and the cubic decimeter, 1 is as already stated, A = 13.5951 

 and this value is here adopted. 



8 is the density of dry air at o°C under the pressure of a column of 

 mercury B n and under standard gravity. The value adopted by the In- 

 ternational Bureau of Weights and Measures for air under the above con- 

 ditions and free from C0 2 is 8 =0.0012928 grams per cubic centimeter. 2 

 This is in close agreement with the value (8 = 0.00129278) used in pre- 

 vious editions of these tables. For air containing 4 parts in 10000 of C0 2 

 it gives a density of 0.00129307, and for air containing 3 parts in 10000 

 of C0 2 , the proportion adopted by Hann, 3 it gives a density of 0.00129301. 

 Therefore, the value adopted for the density of air containing an average 

 amount of C0 2 is 



5 = 0.0012930 



M (Modulus of common logarithms) = 0.4342945. These numbers 

 give for the value of the barometric constant 



K = 18400 meters. 



For the remaining constants, the following values have been used : 

 a = 0.00367 for i° Centigrade. (International Bureau of Weights and 



Measures: Travanx et Memoir es, t. I, p. A. 54.) 



A- = k COS 20 — k' COS 2 2$ + C = O.OO264O COS 2<f> — O.OOOOO7 COS 2 2(j> + 

 O.OOOO45 



R = 6367324 meters. (A. R. Clarke: Geodesy, 8°, Oxford, 1880.) 



i] = — 5— =0.002396. (Ferrel: Report Chief Signal Officer, 1885, pt. 2, 

 R 



pp. 17 and 393.) 



TABLES 61, 52, 53, 54, 56. 

 THE DETERMINATION OF HEIGHTS BY THE BAROMETER. 



Tables 51 , 52, 53, 54, 55. 



English Measures. 



Since a barometric determination of the height will rarely be made at 

 a place where gi is known, the discussion which follows will be confined to 

 the second form of the barometric formula developed in the preceding sec- 

 tion (see page xxxix). For convenience in computing heights it is arranged 

 in the following form: 



Z = K(\ogB Q -\ogB) 





(I + ad) 

 (1 + 0) 



(I + & COS 2 <£ - & r COS 2 2 <£ + C) (I + r?) 

 Z + 2h c 



1 + 



R 



1 Comptes Rendus, Quatrieme Conference Generate Poids et Mesures, 1907, pp. 60-61. 

 8 Leduc, I.e. s Lehrbuch der Meteorologie, dritte Auflage, 1915, s. 5- 



