160 TABLES 144, 145. 



DENSITY OF AIR FOR DIFFERENT PRESSURES AND HUMIDITIES. 



TABLE 144. -Values of 



760' 



from h = 1 to h = 9, for the Computation of Different Values of the Ratio 

 of Actual to Normal Barometric Pressure. 



This gives the density of air at pressure h in terms of the density at normal atmosphere pressure. When the air 

 contains moisture, as is usually the case with the atmosphere, we have the following equation for the dry air 

 pressure : h B 0.378*?, where e is the vapor pressure, and B the observed barometric pressure corrected for 

 temperature. When the necessary observations are made the value of e may be taken from Table 170, and then 

 0.378* from Table 172, or the dew-point may be found and the value of 0.378* taken from Table 172. 



EXAMPLES OF USE OF THE TABLE. 



To find the value of when h = 754.3 

 760 



h 700 gives .92105 



50 l .065789 



4 ' -005263 



3 -000395 



754.3 .99 2 497 



To find the value of when h = 5.73 

 760 



h = 5 gives .0065789 

 .7 ' .0007895 

 .03 " .0000395 



5-73 



.0074079 



TABLE 145. Values of the logarithms of ^ for values of h between 80 and 340. 



Values from 8 to 80 may be got by subtracting i from the characteristic, and from 0.8 to 8 by subtracting 2 from the 



characteristic, and so on. 



SMITHSONIAN TABLES. 



