NEW YORK LIC LIBRARY

@TOR, LENOX AND

LDEN FOUNDATIONS.

TABLES OF SATURATED STEAM.

Weight in pounds of 1,000 cubic feet of saturated steam, or the

weight in pounds of water vapor in 1,000 feet of saturated atmosphere, at a temperature from 32° up to 121°.

རིི ཅེ ཙ

59

68 57 64 55 60

53

55

51 52 49 48

47

4

44

45 40

68

58 64 56 60

55 56

53 3 52 51 48

48

4 45

46 41

72 63 73 61 69 59 65 58 61 56 57 54 53 52

This dew-point and relative humidity table is calculated from a barometric pressure of thirty inches. I have arranged this table for a difference of 8°, running from 60 up to 14° between the wet and dry bulbs, and in temperature from 70° up to 90°. By the use of these tables we can by a little study read the temperatures and work out the amount of water vapor in the atmosphere very readily. Suppose I go to my thermometer, and it stands at 76, 66. Now, by consulting the dew-point, table, I find, in the column marked 10, 61, 59. Then the reading would be 76 dry, 66 wet, 61 dew-point and 59 relative humidity. I find by this that the atmosphere is moistened a little more than one-half it is capable of containing. Now, by looking at the table of saturated steam, we see that at 76° temperature the air is capable of holding 1.39 pounds of water in each 1,000 cubic feet of air; but, as it is only 59 per cent. . saturated, we see at once that the air contains only 0.85 pound; in other words, if we consult our dew-point and humidity table, we shall find that a relative humidity of 59 gives a dew-point of 61. Now, by looking at the table of saturated steam, we find, opposite a temperature of 610, 0.85 pounds. So, if we multiply this by 7.000 (the number of grains in a pound), and divide by 1,000 (the number of cubic feet used as a basis), it will give us the number of grains contained in one cubic foot of air, -0.85 x 7.000 = 5.950 1.000 5.950 grains water vapor. To ascertain the relative humidity from the tables: the weight of 1,000 feet of saturated steam at 61° is 0.85 pound, and at 76° it is 1.39 pounds; now, if we divide 85 by 139, we ascertain the per cent. of relative humidity in the air.

Dew-Point and Absolute Humidity, in Grains.

80 10.936 11.278 11.628 11.988 12.358 12.737 13.127 13.529 13.941 14.362
90 14.794 15.238 15.693 16.160 16.637 17.128 17.631 18.146 18.674 19.216
100 19.771 20.340 20.922 21.518 22.129 22.756 23.397 24.053 24.725 25.413

By the use of this table anyone can ascertain at a glance
what amount of vapor there is in the air. For instance, sup-
pose the dew-point is 66: just run the eye from 60 out to
column marked 6, and we find 7.010 grains.

ATMOSPHERIC CHANGES.

Atmospheric changes in the mills are frequently of great
injury to the work; especially is this the case in the carding
department. Let me give one illustration, as an evidence of
the truth of the statement made. On June 18, 2 P.M., the
temperature was 88 dry, 76 wet, 71 dew-point, 58 relative
humidity, with 8,241 grains of water vapor in a cubic foot of
air; atmosphere very close and sticky. The weight of work
at railway heads run 2.2 per cent. on heavy side. Weight of
sample near the hygrodeik, 1.4 per cent. on heavy side. Wind,
south-west, clear. On June 19, 8 A.M., the temperature was
84 dry, 72 wet, 67 dew-point, 56 relative humidity, with 7,243
grains of water vapor in a cubic foot of air, with a bracing
north-west wind. The weight of work at railway heads