605 



TABLE 640.— PRESSURE OF AQUEOUS VAPOR IN THE ATMOSPHERE: 



SEA LEVEL 



This table gives the vapor pressure corresponding to various values of the difference 

 t — ti between the readings of dry-bulb and wet-bulb thermometers and the temperature ti 

 of the wet-bulb thermometer. The difference t — /, is given by two-degree steps in the top 

 line, and ti by degrees in the first column. Temperatures in Centigrade degrees, vapor 

 pressures in millimeters of mercury are used throughout the table. The table was cal- 

 culated for barometric pressure B equal to 76 cmHg. A correction is given for each 

 centimeter at the top of the columns. Ventilating velocity of wet thermometer about 3 

 meters per second. 



= 0° 



10° 



12° 



14° 



16° 



20° 



Differ- 



ence 

 for 

 0.1° in 



.040 .053 .066 .079 .092 .106 .119 .132 t - h 



— — .050 



— — Example .050 



t=172; f,_10.0; B = 74.5 cmHg 050 



— t — ti = 72 UM 

 ~, From table: 6.17-12X0.050 = 5.57 -J52 



■% ~ For B, 1.5 X .048 = .07 -°$ 



.58 - Hence > = 5 - 64 050 



.88 - - - - - - .050 



1.21 .21 - - - _ _ .050 



1.57 .57 - _____ .050 



1.91 .91 - - - - - .050 



2.27 1.27 .26 - — — - — .050 



2.66 1.66 .65 — — — — — .050 



3.07 2.07 1.06 .05 - - — - .050 



3.51 2.51 1.50 .49 — - - _ .050 



3.98 2.97 1.96 .95 — — — — .050 



4.48 3.47 2.46 1.45 .43 — — — .050 



5.01 4 00 2.98 1.97 .96 — — — .050 



5.57 4.56 3.54 2.53 1.52 .50 — — .050 



6.17 5.15 4.14 3.12 2.11 1.09 .08 - .050 

 6.80 578 4.77 3.75 2.73 1.72 .70 — .051 

 7.47 6 45 5.44 4.42 3.40 2.38 1.37 .35 .051 



8.18 7.16 6.14 5.13 4.11 3.09 2.07 1.05 .051 

 8.93 7.91 6.90 5.88 4.86 3.84 2.82 1.80 .051 

 9.73 8.71 7.69 6.67 5.65 4.63 3.61 2.59 .051 



10.58 9.96 8.53 7.51 6.49 5.47 4.45 3.43 .051 



11.47 10.45 9.42 8.40 7.38 6.36 5.33 4.31 .051 



12.42 11.39 10.37 9.34 8.32 7.30 6.27 5.25 .051 



13.41 12.39 11.36 10.34 9.31 8.29 7.26 6.24 .051 



14.47 13.44 12.42 11.39 10.36 9.34 8.31 7.29 .051 



15.58 14.56 13.53 12.50 11.47 10.45 9.42 8.39 .051 



16.76 15.73 14.70 13.67 12.64 11.62 10.59 10.57 .051 



18.00 16.97 15.94 14.91 13.88 12.85 11.82 10.79 .051 



19.31 18.27 17.24 16.21 15.18 14.15 13.12 12.09 .051 



20.68 19.65 18.62 17.59 16.56 15.52 14.49 13.46 .052 



22.14 21.10 20.07 19.04 18.00 16.97 15.94 14.90 .052 



23.66 22.63 21.60 20.56 19.53 18.49 17.46 16.42 .052 



25 27 24.24 23.20 22.17 21.13 20.10 19.06 18.02 .052 



26 97 25 93 24.89 23.86 22.82 21.78 20.75 19.71 .052 

 28.75 27.71 26.67 25.63 24.60 23.56 22.52 21.48 .052 

 30.62 29.58 28.54 27.50 26.46 25.42 24.38 23.34 .052 

 32.58 31.54 30.50 29.46 28.42 27.38 26.34 25.30 .052 

 34.65 33.61 32.57 31.53 30.49 29.44 28.40 27.36 .052 

 36.82 35.78 34.73 33.69 32.65 31.61 30.57 29.52 .052 

 39.10 38 05 37.01 35.97 34.92 33.88 32.83 31.79 .052 

 4148 40.44 39.40 38.35 37.31 36.26 35.22 34.17 .052 

 43.99 42.94 41.90 40.85 39.81 38.76 37.71 36.67 .052 

 46 61 45 57 44.52 43.47 42.43 41.38 40.33 39.29 .052 

 49 37 48 32 47.27 46.22 45.17 44.12 43.08 42.03 .052 

 52 25 51.20 50.15 49.10 48.05 47.00 45.95 44.00 .052 



SMITHSONIAN PHYSICAL TABLES 



