179 



WEIGHT OF VAPOR, IN GRAINS TROY, CONTAINED IN A CUBIC FOOT OF SATURATED 

 AIR, AT TEMPERATURES BETWEEN 0° AND 94° FAHRENHEIT. 



From the Greenwich Observations. 



Temper- 

 ature 

 of Air, 

 Fabren. 



0° 



1 



2 



3 



4 



5 



6 



7 



8 



9 

 10 

 11 

 12 

 13 

 14 

 15 

 16 

 17 

 18 



Weight 



of Vapor, 



in 



Grains. 



0.78 

 0.81 

 0.84 

 0.87 

 0.90 

 0.93 

 0.97 

 1.00 

 1.04 

 1.07 

 1.11 

 1.15 

 1.19 

 1.24 

 1.28 

 1.32 

 1.37 

 1.41 

 1.47 



Temper- | Weight 



atuie , of Vapor, 



of Air, 



Fahrea. Grains. 



19° 



20 



21 



22 



23 



24 



25 



26 



27 



28 



29 



30 



31 



32 



33 



34 



35 



36 



37 



1.52 

 1.58 

 1.63 

 1.69 

 1.75 

 1.81 

 1.87 

 1.93 

 2.00 

 2.07 

 2.14 

 2.21 

 2.29 

 2.37 

 2.45 

 2.53 

 2.62 

 2.71 

 2.80 



Temper- } Weight 

 ature of Vapor, 

 of Air, 

 Fahren. Grains. 



38 

 39 

 40 

 41 

 42 

 43 

 44 

 45 

 46 

 47 

 48 

 49 

 50 

 51 

 62 

 53 

 54 

 55 

 56 



2.89 

 2.99 

 3.09 

 3.19 

 3.30 

 3.41 

 3.52 

 3.64 

 3.76 

 3,88 

 4.01 

 4.14 

 4.28 

 4.42 

 4.56 

 4.71 

 4.86 

 5.02 

 5.18 



Temper- 

 ature 

 of Air, 

 Fahren. 



57^ 



58 



59 



60 



61 



62 



63 



64 



65 



66 



67 



68 



69 



70 



71 



72 



73 



74 



75 



Weight 



of Vapor, 



in 



Grains. 



5.34 

 5.51 

 5.69 

 5.87 

 6.06 

 6.25 

 6.45 

 6.65 

 6.87 

 7.08 

 7.30 

 7.53 

 7.76 

 8.00 

 8.25 

 8..50 

 8.76 

 9.04 

 9.31 



Temper- 

 ature 

 of Air, 

 Fahren. 



76° 

 77 



78 

 79 

 80 

 81 

 82 

 83 

 84 

 85 

 86 

 87 

 88 

 89 

 90 

 91 

 92 

 93 

 94 



Weight 

 of Vapor, 



Grains. 



9.60 

 9.89 

 10.19 

 10..50 

 10.81 

 11.14 

 11.47 

 11.82 

 12.17 

 12.53 

 12.91 

 13.29 

 13.68 

 14.08 

 14.50 

 14.91 

 15.33 

 15.76 

 16.22 



FACTORS TO DEDUCE THE WEIGHT OF VAPOR CONTAINED IN A CUBIC 

 FOOT OF AIR, AT THE TIME OF A GIVEN OBSERVATION, FROM THE 



INDICATIONS OF DEW-POINT INSTRUMENTS. GrEENW. ObS. 



t = Temperature of Air ; f = Temperature of Dew-Point. 



Use of Table XVI. — The difference between the temperatures of the air 

 and of the Dew-Point being known, multiply the factor in the Table corre- 

 sponding to that difference into the weight of a cubic foot of vapor at the 

 temperature of the Dew-Point, as given in Table XV., and the product will 

 be the weight of vapor in a cubic foot of air at the time of the observation. 



Example. — Temperature of air = 60° F. ; Dew-Point = 52° ; Diff. = 8°. 



Table gives for a difference of 8°, factor 0.984 ; Table XV. gives weight 

 of a cubic foot of vapor at temperature 52° = 4.^''-56. 



Hence, 0.984 x 4.56 = 4^''-A9, the weight of vapor required. 



B 



143 



