16 



CIRCULAR 619, U. S. DEPARTMENT OF AGRICULTURE 



until the 100° F. dry-bulb temperature line is reached. The relative 

 humidity at this point reads 71 percent. 



20 4 60 BO /OO n 20 46 60 60 100 



.041 



20 40 €0 60 /OO 



PEL A T/VE HUM/D/r V (PES? C£Mr) 

 Df?Y A/f? 



ZO 40 60 30 /OO 



£>ELA T/]/£ /-/UM/D/Tvfa£/?CENT) 



WAT£# VAPOX ' 



Figure 3. — Pounds of dry air and of water vapor per cubic foot, at a barometer 

 reading of 29.921 (based on table 1, p. 430, v. 1, of Mechanical Equipment of 

 Buildings, by Luis Allen Harding and Arthur Culls Willard, 1917). 



Example: To find the temperature at which the air under the 

 foregoing conditions would reach 100 percent saturation. 



