Table 1 70. 

 PRESSURE OF AQUEOUS VAPOR IN THE ATMOSPHERE. 



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

 dry and wet bulb thcrnioim:tcrs and the temperature /, of the wet bulb thermometer. The diflfereiices / — /, arc 

 given by two-degree steps in the top hne, and /, by degrees in the lirst column. Temperatures in Centigrade 

 degrees and Kegnault's vapor i>ressures in millimetres ot mercury are used throughout the table. The table was 

 calculated fur barometric pressure B equal to 70 centimetres, and a correction is given for each cenlimetre at the 

 top of the columns,* 



* The table was calculated from the formula /=/i — o.ooo66.5(/—(',) (i +0.00115/1) (Ferrel, Annual Report 

 U. S. Chief Signal Officer, 1.S86, App. 241. 



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. 



