TABLE 150. 

 PRESSURE OF AQUEOUS VAPOR IN THE ATMOSPHERE. 



157 



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 t of the wet bulb thermometer. The differences t t\ are 

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

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

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

 top of the columns.* V entilating velocity of wet thermometer about 3 meters per second. 



* The table was calculated from the formula ^=/ 1 0.00066 ^(i^) (i +0.00115^) (Ferrel, Annual Report 

 U. S. Chief Signal Officer, 1886, 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. 



