MISCELLANEOUS TABLES. Iv 



or the weight of one cubic centimetre, is 0.00129305 gramme. (Inter- 

 national Bureau of Weights and Measures : Travaux d Mcmoircs, t. i, 

 p. A 54.) 



In English measures, the formula becomes 



g^ 0.00129305 //^ — 0.378 ^\ 



I X 0.0020389 (/ — 32°) \ 29.921 / 



where 8 is defined as before, but b and e are expressed in inches and / in 

 Fahrenheit degrees. Thus by the use of tables based on these two formulae, 

 lines of equal atmospheric density may be drawn for the whole world 

 (neglecting slight variations in gravity), whether the original observations 

 are in English or metric measures. Prof. Cleveland Abbe has kindly fur- 

 nished for the present volume the logarithms of the density given in the 

 accompanying tables (81 to 86). 



TABLE 81. 



Table 81. Density of air at differeiit temperatures Fahrenheit. 



This table gives the values and logarithms of the expression 



0.00129305 

 I + 0.0020389 (/ — 32°) 



for values of / extending from —45° F. to 140° F., the intervals between 

 0° F. and 110° F. being 1° 



The tabular values are given to five significant figures. 



TABLES 82. 83. 



Density of air at different humidities and pressures — English measures. 

 Table 82. Term for humidity ; auxiliary to Table 83, 



rr 7 r b — O.X']'^ e 



TABLE 83. Values of ^' . 



29.921 



Table 82 gives values of 0.378 e to three decimal places as an aid to the 

 use of Table 83. 



The argument is the dew-point given for every degree from — 40° F. to 

 140° F. A second column gives the corresponding values of the vapor 

 pressure (<?) according to Broch. 



Table 83 gives values and logarithms of = ~ for values 



29.921 29.921 



of h extending from 1 0.0 to 31.7 inches. The logarithms are given to five 

 significant figures and the corresponding numbers to four decimals. 



Example : 



The air temperature is 68° F., the pressure is 29.36 inches and the dew- 

 point 51" F. Find the logarithm of the density. 

 Table 81, for / = 68.° F. , gives 7.08085 — 10 



Table 82, for dew-point 50°, gives 0.378 <? = o. 141 inch, 

 Table 83, for h — d — 0.378 e = 29.36 — 0.14 = 29.22, gives 9.98941 — 10 



30 



Logarithm of density = 7.07056 — 10 



