Table 140. 

 PRESSURE OF AQUEOUS VAPOR IN THE ATMOSPHERE. 



155 



This table gives the vapor pressure corresponding to various values of the difference t — t-^ between the readings of 

 dry and wet bulb thermometers and the temperature /j of the wet bulb thermometer. The differences t — /j are 

 given by two-degree steps in the top line, and t-^ by degrees in the first column. Temperatures in Centigrade 

 degrees and Rcgnault's vapor pressures in millimetres of mercury are used throughout the table. The table was 

 calculated for barometric pressure B equal to 76 centimetres, and a correction is given for each centimetre at the 

 top of the columns.* 



* The table was calculated from the formula /=/j — o.aoo(i6B{t — ;'i) (i +0.001 15/1) (Ferrel, Annual Report 

 U. S. Chief Signal Officer, 1SS6, App. 24). 



t When B is less than 76 the correction is to be added, and when B is greater than 76 it is to be subtracted. 



Smithsonian Tables. 



