CHAPTER XXVI.

METEOROLOGICAL TABLES.

The tables which follow are those which are now in use by the United States Weather Bureau. They were first published in the Instructions for Voluntary Observers issued in 1892, and were reprinted in 1897. The following instructions will be found of service in the use of the tables:—

Table I.—Dew-Point.

The figures in heavy type, arranged in vertical columns at each side of the page, are the air temperatures in degrees Fahrenheit, as recorded by the dry-bulb thermometer. The figures in heavy type, running across the page, denote the differences, in degrees and tenths of degrees, between the dry-bulb and wet-bulb readings, or, technically, the depression of the wet-bulb thermometer. The figures in the vertical columns denote the dew-points. Make your observation of the wet and dry-bulb thermometers and note the difference between the two readings. Find, in the vertical columns of heavy type, the temperature corresponding to your dry-bulb reading, or the nearest temperature to that. Then look along the horizontal lines of figures in heavy type for the figure which corresponds exactly, or most nearly, with the difference between your wet and dry-bulb readings. Look down the vertical column under this latter figure until you reach the horizontal line corresponding to your dry-bulb reading. At this point the figures in the vertical column give the dew-point of the air at the time of your observation.

Example: Air Temperature (dry bulb), 47°; Wet Bulb, 44°; Difference, 3°. On page [148] will be found the table containing

both 47° (dry bulb) and 3° (depression of the dew-point). In the twenty-eighth line of this table and in the seventh column will be found the dew-point, viz., 41°.

Example: Air Temperature, 61.5°; Wet Bulb, 55.5°; Difference, 6°.

In this case 61.5° is not found in the vertical columns of dry-bulb readings, but 61° and 62° are found. The dew-point, with a difference between wet and dry-bulb readings of 6°, for an air temperature of 61°, is 50°; for an air temperature of 62°, it is 52°. Evidently, then, for an air temperature of 61.5° the dew-point will be 51°, i.e., halfway between 50° and 52°. This method of determining dew-points at air temperatures or with depressions of the wet-bulb thermometer which are not given exactly in the tables, is known as interpolation.

Example: Air Temperature, 93°; Wet Bulb, 90.5°; Difference, 2.5°. Our table gives no dew-points for wet-bulb depressions of 2.5°, with air temperature 93°, but we find (on page [152]) that for air temperature 93° and depression of wet bulb of 2°, the dew-point is 91°, while for a wet-bulb depression of 3°, the dew-point is 89°. By the method of interpolation we can readily determine the dew-point in the special case under consideration as 90°, i.e., halfway between 89° and 91°.

Table II.—Relative Humidity.

The general plan of this table is the same as that of Table I. The figures in the vertical columns are the relative humidities (in percentages) corresponding to the different readings of the wet and dry-bulb thermometers.

Table III.—Reduction of Barometer to 32°.

The figures in heavy type, arranged in vertical columns at the left of the page, refer to the temperature in degrees Fahrenheit, as indicated by the attached thermometer. The figures

in heavy type, running across the top of the page, are the barometer readings in inches and tenths. Make a reading of the attached thermometer and of the barometer. Find in the vertical column the temperature corresponding to the reading of the attached thermometer, and in the horizontal line of heavy figures the reading corresponding to the height of the barometer. The decimal in the vertical column, under the appropriate barometer reading, and in the same horizontal line with the appropriate thermometer reading, is to be subtracted from the height of the barometer as observed, thus correcting the reading to freezing. When the attached thermometer reads below 28°, the correction is additive.

Example: Attached Thermometer, 69°; Barometer, 30.00 inches; Correction, -.110; Corrected reading, 29.890 inches.

Example: Attached Thermometer, 73°; Barometer, 29.75 inches; Correction = ?

We do not find any column corresponding to a barometer reading of 29.75 inches. We do find, however, that with a barometer reading of 29.50, and an attached thermometer reading of 73, the correction is -.118 inch, and with a barometer reading of 30.00, the correction is -.120. By interpolating, as in the case of the humidity table above, we find the correction for a barometer reading of 29.75 inches, and an attached thermometer reading of 73°. The correction is -.119, and the corrected reading is 29.75 - .119 = 29.63 inches.

Table IV.—Reduction of Barometer to Sea Level.

The figures in heavy type, in the left-hand vertical columns, are the heights, in feet, of the barometer above sea level. The figures in heavy type at the top of the columns, running across the page, are the readings of the ordinary thermometer. The numbers of inches and hundredths of inches to be subtracted from the barometer reading (corrected for temperature by Table

III), for the different heights above sea level, are given in the vertical columns.

The altitude above sea level of the city or town at which the observation is made should be ascertained as accurately as possible from some recognized authority, as, e.g., from a railroad survey; from Government measurements, or from some engineer’s office. The correction to be made is determined by a simple inspection of the table or by the method of interpolation.

Example: Altitude of Barometer above sea level, 840 feet; Temperature of the air, 40°; Correction, +.931 inch.

Example: Altitude of Barometer above sea level, 205 feet; Temperature of the air, 45°; Correction = ?

Here 205 feet and 45° are neither of them found in the table. Hence a double interpolation is necessary. For 200 feet and 40° the correction is +.224 inch. For 200 feet and 50° the correction is +.220 inch. Hence for 200 feet and 45° the correction is +.222 inch. For 210 feet and 40° the correction is +.235 inch. For 210 feet and 50° the correction is +.231 inch. Hence for 210 feet and 45° the correction is +.233 inch. Now for 205 feet we should have a correction midway between +.235 inch and +.233 inch or +.234 inch.

Table I.—Temperature of the Dew-Point, in Degrees Fahrenheit.

t Difference between the dry and wet thermometers (t-t′) t
(Dry ther.)0°.20°.40°.60°.81°.01°.21°.41°.61°.82°.02°.22°.42°.6(Dry ther.)
-40 -52 -40
-39 -50 -39
-38 -49 -38
-37 -48 -37
-36 -46 -36
-35 -44 -35
-34 -43 -58 -34
-33 -42 -55 -33
-32 -40 -52 -32
-31 -38 -49 -31
-30 -36 -47 -30
-29 -35 -44 -29
-28 -33 -42 -56 -28
-27 -32 -40 -52 -27
-26 -30 -37 -48 -26
-25 -29 -35 -45 -25
-24 -28 -34 -43 -58 -24
-23 -27 -32 -40 -53 -23
-22 -26 -30 -37 -49 -22
-21 -25 -29 -35 -45 -21
-20 -23 -28 -33 -41 -55 -20
-19 -22 -26 -31 -38 -50 -19
-18 -21 -25 -29 -35 -45 -18
-17 -20 -23 -27 -32 -41 -55 -17
-16 -19 -22 -26 -30 -37 -49 -16
-15 -17 -20 -24 -28 -34 -44 -15
-14 -16 -19 -22 -26 -31 -39 -52 -14
-13 -15 -18 -21 -25 -29 -35 -46 -13
-12 -14 -17 -20 -23 -27 -32 -41 -55 -12
-11 -13 -16 -18 -21 -25 -30 -36 -48 -11
-10 -12 -14 -17 -20 -23 -27 -33 -42 -58 -10
-9 -11 -13 -15 -18 -21 -25 -30 -37 -48 -9
-8 -10 -12 -14 -17 -20 -23 -27 -33 -42 -58 -8
-7 -9 -11 -13 -15 -18 -21 -25 -30 -36 -48 -7
-6 -8 -10 -12 -14 -16 -19 -23 -27 -32 -41 -56 -6
-5 -7 -8 -10 -12 -15 -17 -21 -24 -29 -35 -47 -5
-4 -6 -7 -9 -11 -13 -16 -19 -22 -26 -31 -39 -54 -4
-3 -4 -6 -8 -10 -12 -14 -17 -20 -23 -28 -33 -44 -3
-2 -3 -5 -6 -8 -10 -12 -15 -18 -21 -24 -29 -36 -48 -2
-1 -2 -4 -5 -7 -9 -11 -13 -16 -18 -22 -26 -31 -39 -1
±0 -1 -3 -4 -6 -7 -9 -11 -14 -16 -19 -23 -27 -33 0
+1 -0 -2 -3 -4 -6 -8 -10 -12 -14 -17 -20 -24 -28 +1
2 +1 -1 -2 -3 -5 -6 -8 -10 -12 -15 -17 -21 -25 2
3 2 +1 -1 -2 -3 -5 -7 -8 -10 -13 -15 -18 -21 3
4 3 +2 0 -1 -2 -4 -5 -7 -9 -11 -13 -16 -19 4
5 4 3 +1 0 -1 -2 -4 -5 -7 -9 -11 -14 -16 5
6 5 4 3 +1 0 -1 -3 -4 -6 -7 -9 -12 -14 6
7 6 5 4 3 +1 0 -1 -3 -4 -6 -8 -10 -12 7
8 7 6 5 4 3 +1 0 -1 -3 -4 -6 -8 -10 8
9 8 7 6 5 4 3 +1 0 -1 -3 -4 -6 -8 9
10 9 8 7 6 5 4 3 +1 0 -1 -3 -4 -6 10
11 10 9 8 7 6 5 4 3 +2 0 -1 -3 -4 11
12 11 10 9 9 8 7 5 4 3 +2 0 -1 -2 12
13 12 11 11 10 9 8 7 6 5 3 +2 +1 -1 13
14 13 12 12 11 10 9 8 7 6 5 4 2 +1 14
15 14 13 13 12 11 10 9 8 7 6 5 4 3 15
16 15 15 14 13 12 11 10 10 9 8 7 5 4 16
17 16 16 15 14 13 12 12 11 10 9 8 7 6 17
18 17 17 16 15 14 14 13 12 11 10 9 8 7 18
19 18 18 17 16 15 15 14 13 12 11 10 10 9 19
20 19 19 18 17 17 16 15 14 13 13 12 11 10 20
t.0°.2 0°.40°.6 0°.81°.01°.21°.41°.61°.82°.02°.22°.42°.6 t.

Table I.—Temperature of the Dew-Point, in Degrees Fahrenheit.

t Difference between the dry and wet thermometers (t-t′). t
(Dry ther.) 2°.6 2°.8 3°.0 3°.2 3°.4 3°.6 3°.8 4°.0 4°.2 4°.4(Dry ther.)
-2 -48 -2
-1 -39 -54 -1
0 -33 -43 0
+1 -28 -35 -46 +1
2 -25 -30 -37 -50 2
3 -21 -26 -31 -39 -54 3
4 -19 -22 -27 -32 -42 -60 4
5 -16 -19 -23 -28 -34 -45 5
6 -14 -17 -20 -24 -29 -35 -47 6
7 -12 -14 -17 -20 -24 -29 -37 -50 7
8 -10 -12 -15 -17 -21 -25 -30 -38 -53 8
9 -8 -10 -12 -15 -18 -21 -25 -31 -39 -55 9
10 -6 -8 -10 -12 -15 -18 -21 -26 -31 -40 10
11 -4 -6 -8 -10 -12 -15 -18 -21 -26 -31 11
12 -2 -4 -6 -8 -10 -12 -15 -18 -21 -26 12
13 -1 -2 -4 -5 -7 -9 -12 -14 -17 -21 13
14 +1 0 -2 -3 -5 -7 -9 -11 -14 -17 14
15 3 +1 0 -2 -3 -5 -7 -9 -11 -14 15
16 4 3 +2 0 -1 -3 -4 -6 -8 -10 16
17 6 5 3 +2 +1 -1 -2 -4 -6 -8 17
18 7 6 5 4 2 +1 0 -2 -3 -5 18
19 9 8 7 5 4 3 +1 0 -1 -3 19
20 10 9 8 7 6 5 3 +2 +1 -1 20
t. 2°.6 2°.8 3°.0 3°.2 3°.4 3°.6 3°.8 4°.0 4°.2 4°.4 t.
t. 4°.6 4°.8 5°.0 5°.2 5°.4 5°.6 5°.8 6°.0 6°.2 6°.4 t.
8 8
9 9
10 -57 10
11 -41 -60 11
12 -31 -41 -59 12
13 -25 -31 -40 -58 13
14 -20 -25 -30 -39 -56 14
15 -16 -20 -24 -30 -38 -53 15
16 -13 -16 -19 -23 -28 -36 -50 16
17 -10 -12 -15 -18 -22 -27 -34 -47 17
18 -7 -9 -12 -14 -17 -21 -26 -32 -44 18
19 -5 -7 -9 -11 -14 -17 -20 -25 -30 -40 19
20 -2 -4 -6 -8 -10 -13 -16 -19 -23 -29 20
t. 4°.6 4°.8 5°.0 5°.2 5°.4 5°.6 5°.8 6°.0 6°.2 6°.4 t.

Table I.—Temperature of the Dew-Point, in Degrees Fahrenheit.

t Difference between the dry and wet thermometers (t-t′). t
(Dry ther.)0°.51°.01°.52°.02°.53°.03°.54°.04°.55°.05°.56°.0(Dry ther.)
20 18 17 15 13 10 8 5 2 -2 -6-12-19 20
21 19 18 16 14 12 9 7 4 0 -4 -8-15 21
22 20 19 17 15 13 11 8 6 +2 -1 -6-11 22
23 22 20 18 16 14 12 10 7 4 +1 -3 -8 23
24 23 21 19 18 16 14 11 9 6 3 -1 -5 24
25 24 22 21 19 17 15 13 11 8 5 +2 -2 25
26 25 23 22 20 18 16 14 12 10 7 4 0 26
27 26 24 23 21 20 18 16 14 11 9 6 +3 27
28 27 25 24 22 21 19 17 15 13 11 8 5 28
29 28 26 25 24 22 20 19 17 14 12 10 7 29
30 29 27 26 25 23 22 20 18 16 14 11 9 30
31 30 29 27 26 24 23 21 19 18 15 13 11 31
32 31 30 28 27 26 24 22 21 19 17 15 13 32
33 31 31 29 28 26 25 23 22 19 18 16 14 33
34 32 32 30 29 27 26 24 24 21 20 18 16 34
35 33 32 31 30 29 28 26 25 23 22 20 18 35
36 35 34 32 31 30 29 27 26 24 23 21 19 36
37 36 35 33 32 31 30 28 27 26 24 22 21 37
38 37 36 34 33 32 31 30 28 27 26 24 22 38
39 38 37 35 34 33 32 30 29 28 27 25 24 39
40 39 38 36 35 34 33 31 30 29 28 26 25 40
41 40 39 37 36 35 34 32 32 30 29 28 26 41
42 41 40 39 38 36 35 34 33 31 30 29 27 42
43 42 41 40 39 37 36 35 34 32 31 30 29 43
44 43 42 41 40 38 37 36 35 33 32 31 30 44
45 44 43 42 41 40 39 37 36 34 33 32 31 45
46 45 44 43 42 41 40 38 37 36 35 33 32 46
47 46 45 44 43 42 41 40 39 37 36 34 33 47
48 47 46 45 44 43 42 41 40 38 37 36 35 48
49 48 47 46 45 44 43 42 41 39 38 37 36 49
50 49 48 47 46 45 44 43 42 41 40 38 37 50
51 50 49 48 47 46 45 44 43 42 41 39 38 51
52 51 50 49 48 47 46 45 44 43 42 41 40 52
53 52 51 50 49 48 47 46 45 44 43 42 41 53
54 53 52 51 50 50 49 47 46 45 44 43 42 54
55 54 53 53 52 51 50 49 48 47 46 44 43 55
56 55 54 54 53 52 51 50 49 48 47 45 44 56
57 56 55 55 54 53 52 51 50 49 48 47 46 57
58 57 56 56 55 54 53 52 51 50 49 48 47 58
59 58 57 57 56 55 54 53 52 51 50 49 48 59
60 59 58 58 57 56 55 54 53 52 51 50 49 60
61 60 59 59 58 57 56 55 54 53 52 51 50 61
62 61 60 60 59 58 57 56 55 54 53 52 52 62
63 62 61 61 60 59 58 57 56 55 55 54 53 63
64 63 62 62 61 60 59 58 57 56 56 55 54 64
65 64 63 63 62 61 60 59 59 58 57 56 55 65
66 65 64 64 63 62 61 60 60 59 58 57 56 66
67 67 66 65 64 63 62 61 61 60 59 58 57 67
68 68 67 66 65 64 63 62 62 61 60 59 58 68
69 69 68 67 66 65 64 63 63 62 61 60 59 69
70 70 69 68 67 67 66 65 64 63 62 61 61 70
71 71 70 69 68 68 67 66 65 64 63 62 62 71
72 72 71 70 69 69 68 67 66 65 64 63 63 72
73 73 72 71 70 70 69 68 67 66 66 65 64 73
74 74 73 72 71 71 70 69 68 67 67 66 65 74
75 75 74 73 72 72 71 70 69 68 68 67 66 75
76 76 75 74 73 73 72 71 70 69 69 68 67 76
77 77 76 75 74 74 73 72 71 70 70 69 68 77
78 78 77 76 75 75 74 73 72 71 71 70 69 78
79 79 78 77 76 76 75 74 73 72 72 71 70 79
80 80 79 78 77 77 76 75 74 73 73 72 72 80
t.0°.51°.01°.52°.02°.53°.03°.54°.04°.55°.05°.56°.0 t.

Table I.—Temperature of the Dew-Point, in Degrees Fahrenheit.

t Difference between the dry and wet thermometers (t-t′). t
(Dry ther.) 6°.0 6°.5 7°.0 7°.5 8°.0 8°.5 9°.0 9°.510°.010°.511°.011°.512°.0 (Dry ther.)
19 -25 19
20 -19 -32 20
21 -15 -24 -47 21
22 -11 -19 -31 22
23 -8 -14 -24 -45 23
24 -5 -10 -18 -30 24
25 -2 -7 -13 -22 -42 25
26 0 -4 -9 -17 -28 26
27 +3 -1 -6 -12 -20 -37 27
28 5 +1 -3 -8 -15 -25 -54 28
29 7 4 0 -4 -10 -18 -32 29
30 9 6 +2 -2 -6 -13 -22 -43 30
31 11 8 5 +1 -3 -8 -15 -27 31
32 13 10 7 4 0 -4 -10 -18 -33 32
33 14 12 9 6 +3 -1 -6 -12 -22 -44 33
34 16 14 11 8 6 +2 -2 -8 -15 -27 34
35 18 15 13 10 8 5 +1 -4 -9 -18 -32 35
36 19 17 15 12 10 8 4 0 -5 -12 -20 -42 36
37 21 19 17 14 12 9 6 +3 -2 -6 -14 -25 -52 37
38 22 20 19 16 14 11 9 6 +2 -2 -8 -16 -29 38
39 24 22 20 18 16 14 11 8 5 +1 -4 -10 -18 39
40 25 23 22 20 18 16 13 11 8 4 0 -5 -12 40
41 26 25 23 21 20 17 15 13 10 7 +4 -1 -6 41
42 27 26 24 23 21 19 18 15 12 10 7 +3 -2 42
43 29 27 26 24 23 21 19 17 14 12 9 6 +2 43
44 30 28 27 26 24 22 20 18 16 14 12 9 6 44
45 31 30 28 27 25 24 22 20 18 16 13 11 8 45
46 32 31 30 28 27 25 24 22 20 18 16 13 11 46
47 33 32 31 29 28 26 25 23 22 20 18 15 13 47
48 35 33 32 30 29 28 26 25 23 21 20 17 15 48
49 36 34 33 32 31 29 28 26 25 23 21 19 17 49
50 37 35 34 33 32 31 29 28 26 24 23 21 19 50
51 38 37 36 34 33 32 31 29 28 26 24 22 21 51
52 40 38 37 36 34 33 32 30 29 28 26 24 23 52
53 41 39 38 37 36 34 33 32 30 29 28 26 24 53
54 42 41 40 39 37 36 34 33 32 30 29 27 26 54
55 43 42 41 40 39 37 36 34 33 32 30 29 28 55
56 44 43 42 41 40 39 37 36 34 33 32 30 29 56
57 46 45 44 42 41 40 39 37 36 35 33 32 30 57
58 47 46 45 44 42 41 40 39 37 36 35 33 32 58
59 48 47 46 45 44 43 41 40 39 38 36 35 33 59
60 49 48 47 46 45 44 43 41 40 39 38 36 35 60
61 50 49 48 47 46 45 44 43 42 41 39 38 36 61
62 52 51 50 49 48 47 45 44 43 42 41 39 38 62
63 53 52 51 50 49 48 47 45 44 43 42 41 39 63
64 54 53 52 51 50 49 48 47 46 45 43 42 41 64
65 55 54 53 52 51 50 49 48 47 46 45 43 42 65
66 56 55 54 53 52 51 50 49 48 47 46 45 44 66
67 57 56 55 55 54 53 52 51 50 48 47 46 45 67
68 58 57 57 56 55 54 53 52 51 50 49 47 46 68
69 59 58 58 57 56 55 54 53 52 51 50 49 48 69
70 61 60 59 58 57 56 55 54 53 52 51 50 49 70
71 62 61 60 59 58 57 56 55 55 54 53 52 51 71
72 63 62 61 60 59 59 58 57 56 55 54 53 52 72
73 64 63 62 62 61 60 59 58 57 56 55 54 53 73
74 65 64 63 63 62 61 60 59 58 57 56 55 54 74
75 66 65 64 64 63 62 61 60 59 58 57 56 56 75
76 67 66 65 65 64 63 62 61 61 60 59 58 57 76
77 68 67 67 66 65 64 63 62 62 61 60 59 58 77
78 69 68 68 67 66 66 65 64 63 62 61 60 59 78
79 70 69 69 68 67 67 66 65 64 63 62 61 61 79
80 72 71 70 69 68 68 67 66 65 64 63 62 62 80
t. 6°.0 6°.5 7°.0 7°.5 8°.0 8°.5 9°.0 9°.510°.010°.511°.011°.512°.0 t.

Table I.—Temperature of the Dew-Point, in Degrees Fahrenheit.

t Difference between the dry and wet thermometers (t-t′). t
(Dry ther.)12°.012°.513°.013°.514°.014°.515°.015°.516°.016°.517°.017°.518°.0(Dry ther.)
40 -12 -22 -44 40
41 -6 -13 -25 41
42 -2 -7 -15 -28 42
43 +2 -3 -8 -17 -33 43
44 6 +1 -4 -10 -19 -40 44
45 8 5 0 -4 -11 -22 -48 45
46 11 8 +4 0 -5 -13 -24 46
47 13 10 7 +3 -1 -6 -14 -27 47
48 15 12 10 6 +2 -2 -8 -16 -30 48
49 17 14 12 9 6 +2 -3 -9 -18 -35 49
50 19 16 14 12 9 5 +1 -4 -10 -20 -42 50
51 21 18 17 14 11 8 5 0 -5 -12 -22 -52 51
52 23 21 19 16 14 11 8 +4 0 -6 -13 -25 52
53 24 22 20 18 16 14 11 8 +4 -1 -6 -14 -28 53
54 26 24 22 20 18 16 13 10 7 +3 -2 -8 -16 54
55 28 26 24 22 20 18 16 13 10 7 +3 -2 -8 55
56 29 27 26 24 22 20 18 15 13 10 6 +2 -2 56
57 30 29 28 26 24 22 20 18 15 13 10 6 +2 57
58 32 30 29 27 26 24 22 20 18 15 12 9 6 58
59 33 32 31 29 27 26 24 22 20 18 15 12 9 59
60 35 33 32 30 29 27 26 24 22 20 18 15 12 60
61 36 35 33 32 31 29 28 26 24 22 20 18 15 61
62 38 37 35 34 32 31 29 28 26 24 22 20 18 62
63 39 38 37 35 34 32 31 29 28 26 24 22 20 63
64 41 39 38 37 35 34 32 31 29 28 26 24 22 64
65 42 41 40 38 37 35 34 32 31 29 28 26 24 65
66 44 43 41 40 38 37 35 34 32 31 30 28 26 66
67 45 44 43 41 40 39 37 36 34 32 31 30 28 67
68 46 45 44 43 42 40 39 38 36 34 33 31 30 68
69 48 47 46 45 43 42 40 39 38 36 34 33 32 69
70 49 48 47 46 45 43 42 41 39 38 36 35 33 70
71 51 49 48 47 46 45 43 42 41 39 38 36 35 71
72 52 51 50 49 47 46 45 44 43 41 40 38 37 72
73 53 52 51 50 49 48 46 45 44 43 41 40 38 73
74 54 53 52 51 50 49 48 47 45 44 43 41 40 74
75 56 55 54 53 52 50 49 48 47 45 44 43 42 75
76 57 56 55 54 53 52 50 49 48 47 46 45 43 76
77 58 57 56 55 54 53 52 51 50 49 48 46 45 77
78 59 58 57 56 55 54 53 52 51 50 49 48 47 78
79 61 60 59 58 57 56 55 54 53 52 51 49 48 79
80 62 61 60 59 58 57 56 55 54 53 52 51 50 80
t.12°.012°.513°.013°.514°.014°.515°.015°.516°.016°.517°.017°.518°.0 t.

Table I.—Temperature of the Dew-Point, in Degrees Fahrenheit.

t Difference between the dry and wet thermometers (t-t′). t
(Dry ther.)18°.019°.020°.021°.022°.023°.024°.025°.026°.027°.028°.029°.030°.0(Dry ther.)
55 -8 55
56 -2 -19 56
57 +2 -10 -48 57
58 6 -3 -22 58
59 9 +1 -12 59
60 12 5 -5 -25 60
61 15 9 0 -14 61
62 18 12 +5 -6 -28 62
63 20 15 9 0 -14 63
64 22 18 12 +4 -6 -32 64
65 24 20 15 9 0 -16 65
66 26 22 18 12 +4 -7 -34 66
67 28 24 20 15 9 -1 -16 67
68 30 26 23 18 12 +4 -7 -37 68
69 32 28 25 20 15 8 0 -17 69
70 33 30 27 23 19 12 +5 -7 -39 70
71 35 32 29 25 21 16 9 0 -17 71
72 37 33 31 27 23 18 13 +5 -6 -39 72
73 38 35 32 29 25 21 16 10 0 -16 73
74 40 37 34 31 28 24 19 13 +6 -6 -37 74
75 42 39 36 32 30 26 22 16 10 0 -16 75
76 43 41 38 34 32 28 24 20 14 +6 -6 -34 76
77 45 42 40 36 33 30 26 22 17 11 +1 -14 77
78 47 44 41 38 35 32 28 24 20 14 7 -4 -30 78
79 48 46 43 40 37 34 31 27 23 18 11 +2 -13 79
80 50 47 45 42 39 36 32 29 25 21 15 8 -3 80
t18°.019°.020°.021°.022°.023°.024°.025°.026°.027°.028°.029°.030°.0 t

Table I.—Temperature of the Dew-Point, in Degrees Fahrenheit.

t Difference between the dry and wet thermometers (t-t′). t
(Dry ther.)1°.02°.03°.04°.05°.06°.07°.08°.09°.010°.011°.012°.0(Dry ther.)
80 79 77 76 74 73 72 70 68 67 65 63 62 80
81 80 78 77 75 74 73 71 70 68 66 65 63 81
82 81 79 78 77 75 74 72 71 69 68 66 64 82
83 82 80 79 78 76 75 73 72 70 69 67 65 83
84 83 81 80 79 77 76 74 73 71 70 68 67 84
85 84 82 81 80 78 77 75 74 72 71 69 68 85
86 85 83 82 81 79 78 76 75 73 72 71 69 86
87 86 84 83 82 80 79 78 76 74 73 72 70 87
88 87 85 84 83 81 80 79 77 75 74 73 71 88
89 88 86 85 84 82 81 80 78 76 76 74 72 89
90 89 87 86 85 84 82 81 79 78 77 75 74 90
91 90 88 87 86 85 83 82 80 79 78 76 75 91
92 91 89 88 87 86 84 83 82 80 79 77 76 92
93 92 91 89 88 87 85 84 83 81 80 78 77 93
94 93 92 90 89 88 86 85 84 82 81 80 78 94
95 94 93 91 90 89 87 86 85 83 82 81 79 95
96 95 94 92 91 90 88 87 86 84 83 82 80 96
97 96 95 93 92 91 90 88 87 86 84 83 81 97
98 97 96 94 93 92 91 89 88 87 85 84 83 98
99 98 97 95 94 93 92 90 89 88 86 85 84 99
100 99 98 96 95 94 93 91 90 89 87 86 85 100
101100 99 97 96 95 94 92 91 90 88 87 86 101
102101100 98 97 96 95 93 92 91 90 88 87 102
103102101 99 98 97 96 94 93 92 91 89 88 103
104103102100 99 98 97 96 94 93 92 90 89 104
105104103101100 99 98 97 95 94 93 91 90 105
106105104102101100 99 98 96 95 94 93 91 106
107106105103102101100 99 97 96 95 94 92 107
108107106104103102101100 98 97 96 95 93 108
109108107105104103102101 99 98 97 96 94 109
110109108107105104103102101 99 98 97 96 110
t.1°.02°.03°.04°.05°.06°.07°.08°.09°.010°.011°.012°.0 t.

Table I.—Temperature of the Dew-Point, in Degrees Fahrenheit.

t Difference between the dry and wet thermometers (t-t′). t
(Dry ther.)12°.013°.014°.015°.016°.017°.018°.019°.020°.021°.022°.023°.024°.0(Dry ther.)
80 62 60 58 56 54 52 50 47 45 42 39 36 32 80
81 63 61 59 57 55 53 51 49 47 44 41 38 35 81
82 64 62 61 59 57 55 53 50 48 45 43 40 37 82
83 65 64 62 60 58 56 54 52 50 47 44 42 39 83
84 67 65 63 61 59 57 55 53 51 49 46 43 41 84
85 68 66 64 62 61 59 57 55 53 50 48 45 42 85
86 69 67 66 64 62 60 58 56 54 52 49 47 44 86
87 70 68 67 65 63 61 59 57 55 53 51 48 46 87
88 71 70 68 66 64 63 61 59 57 55 53 50 48 88
89 72 71 69 67 66 64 62 60 58 56 54 52 49 89
90 74 72 70 69 67 65 63 62 60 58 56 53 51 90
91 75 73 72 70 68 67 65 63 61 59 57 55 53 91
92 76 74 73 71 69 68 66 64 62 60 58 56 54 92
93 77 75 74 72 71 69 67 66 64 62 60 58 56 93
94 78 77 75 73 72 70 69 67 65 63 61 59 57 94
95 79 78 76 75 73 71 70 68 66 64 63 61 59 95
96 80 79 77 76 74 73 71 69 68 66 64 62 60 96
97 81 80 78 77 75 74 72 71 69 67 65 63 61 97
98 83 81 80 78 77 75 73 72 70 68 67 65 63 98
99 84 82 81 79 78 76 75 73 71 70 68 66 64 99
100 85 83 82 80 79 77 76 74 73 71 69 67 66 100
101 86 84 83 82 80 79 77 75 74 72 71 69 67 101
102 87 85 84 83 81 80 78 77 75 73 72 70 68 102
103 88 87 85 84 82 81 79 78 76 75 73 71 70 103
104 89 88 86 85 83 82 81 79 78 76 74 73 71 104
105 90 89 87 86 85 83 82 80 79 77 76 74 72 105
106 91 90 89 87 86 84 83 81 80 78 77 75 74 106
107 92 91 90 88 87 85 84 83 81 80 78 76 75 107
108 93 92 91 89 88 87 85 84 82 81 79 78 76 108
109 94 93 92 90 89 88 86 85 83 82 80 79 77 109
110 96 94 93 92 90 89 87 86 85 83 82 80 79 110
t.12°.013°.014°.015°.016°.017°.018°.019°.020°.021°.022°.023°.024°.0 t.

Table I.—Temperature of the Dew-Point, in Degrees Fahrenheit.

t Difference between the dry and wet thermometers (t-t′). t
(Dry ther.)24°.025°.026°.027°.028°.029°.030°.031°.032°.033°.034°.035°.036°.0(Dry ther.)
80 32 29 25 21 15 8 -3 -27 80
81 35 31 28 24 18 12 +3 -11 81
82 37 33 30 26 22 16 9 -2 -24 82
83 39 35 32 28 24 19 13 +5 -9 83
84 41 37 34 30 27 22 17 10 0 -20 84
85 42 39 36 32 29 25 20 14 +6 -7 -54 85
86 44 41 38 35 31 28 23 18 11 +1 -17 86
87 46 43 40 37 33 30 26 21 15 7 -5 -38 87
88 48 45 42 39 35 32 28 24 19 12 +3 -13 88
89 49 47 44 41 38 34 31 27 22 16 9 -2 -28 89
90 51 48 46 43 40 36 32 29 25 20 13 +4 -10 90
91 53 50 47 45 42 38 35 32 28 23 18 10 0 91
92 54 52 49 46 44 41 37 34 30 26 21 15 +7 92
93 56 53 51 48 46 43 39 36 32 29 24 19 12 93
94 57 55 53 50 47 45 42 38 35 31 27 22 16 94
95 59 56 54 52 49 46 44 40 37 33 30 25 20 95
96 60 58 56 53 51 48 46 43 39 36 32 28 24 96
97 61 59 57 55 53 50 47 45 41 38 34 31 26 97
98 63 61 59 57 54 52 49 47 44 40 37 33 29 98
99 64 62 60 58 56 54 51 48 46 43 39 35 32 99
100 66 64 62 60 57 55 53 50 48 45 41 38 34 100
101 67 65 63 61 59 57 54 52 49 47 44 40 37 101
102 68 66 65 63 61 58 56 54 51 49 46 43 39 102
103 70 68 66 64 62 60 58 55 53 50 48 45 41 103
104 71 69 67 65 63 61 59 57 55 52 50 47 44 104
105 72 70 69 67 65 63 61 59 56 54 52 49 46 105
106 74 72 70 68 66 64 62 60 58 56 53 51 48 106
107 75 73 71 70 68 66 64 62 60 57 55 52 50 107
108 76 74 73 71 69 67 65 63 61 59 57 54 52 108
109 77 76 74 72 71 69 67 65 63 61 58 56 54 109
110 79 77 75 74 72 70 68 66 64 62 60 58 55 110
t.24°.025°.026°.027°.028°.029°.030°.031°.032°.033°.034°.035°.036°.0 t.

Table I.—Temperature of the Dew-Point, in Degrees Fahrenheit.

t Difference between the dry and wet thermometers (t-t′). t
(Dry ther.)36°.037°.038°.039°.040°.041°.042°.043°.044°.045°.046°.047°.048°.0(Dry ther.)
89 -28 89
90 -10 90
91 0 -22 91
92 +7 -7 -16 92
93 12 +2 -4 93
94 16 8 +4 -37 94
95 20 13 10 -12 95
96 24 15 15 -1 -25 96
97 26 21 19 +7 -8 97
98 29 25 23 12 +2 -18 98
99 32 28 26 17 9 -4 -42 99
100 34 30 29 21 14 +5 -12 100
101 37 32 32 24 18 11 0 -25 101
102 39 35 34 27 22 16 +7 -7 102
103 41 38 34 30 26 20 13 +3 -16 103
104 44 40 37 32 29 24 18 10 -2 -38 104
105 46 43 39 35 31 27 22 15 +6 -10 105
106 48 45 42 38 34 30 25 20 12 +1 -22 106
107 50 47 44 40 37 32 28 24 17 9 -5 107
108 52 49 46 43 39 35 31 27 21 14 +5 -13 108
109 54 51 48 45 42 38 34 30 25 19 12 0 -28 109
110 55 53 50 47 44 41 37 33 28 23 17 +8 -7 110
t.36°.037°.038°.039°.040°.041°.042°.043°.044°.045°.046°.047°.048°.0 t.

Table II.—Relative Humidity, per cent.

t Difference between the dry and wet thermometers (t—t′). t
(Dry ther.)0°.20°.40°.60°.81°.01°.21°.41°.61°.82°.02°.22°.42°.6(Dry ther.)
-40 46 -40
-39 49 -39
-38 51 -38
-37 54 -37
-36 56 -36
-35 59 -35
-34 61 22 -34
-33 63 25 -33
-32 65 30 -32
-31 67 34 -31
-30 69 38 -30
-29 71 42 -29
-28 72 45 17 -28
-27 74 48 22 -27
-26 76 51 26 -26
-25 77 53 31 -25
-24 78 56 34 12 -24
-23 79 58 37 16 -23
-22 80 60 40 20 -22
-21 81 62 44 25 -21
-20 82 64 47 29 11 -20
-19 83 66 49 33 16 -19
-18 84 68 52 36 20 -18
-17 85 70 54 39 24 9 -17
-16 86 71 57 43 28 14 -16
-15 86 73 59 46 32 19 -15
-14 87 74 61 48 36 23 10 -14
-13 88 76 63 51 39 27 15 -13
-12 88 77 65 53 42 30 19 7 -12
-11 89 78 67 56 45 34 23 12 -11
-10 90 79 68 58 48 37 26 16 5 -10
-9 90 80 70 60 50 40 30 20 10 -9
-8 90 81 71 62 52 43 33 24 14 5 -8
-7 91 82 73 63 54 45 36 27 18 9 -7
-6 91 83 74 65 56 48 39 31 22 13 5 -6
-5 92 83 75 67 58 50 42 34 25 17 9 -5
-4 92 84 76 68 60 52 45 37 29 21 13 5 -4
-3 92 85 77 70 62 55 47 40 32 25 17 10 -3
-2 93 86 78 71 64 57 50 42 35 28 21 14 7 -2
-1 93 86 79 72 66 59 52 45 38 31 25 18 11 -1
0 93 87 80 74 67 61 54 48 41 35 28 22 15 0
+1 94 87 81 75 69 63 56 50 44 38 32 25 19 +1
2 94 88 82 76 70 64 58 52 46 40 35 29 23 2
3 94 88 83 77 71 66 60 54 49 43 37 32 26 3
4 94 89 83 78 73 67 62 56 51 45 40 34 29 4
5 95 89 84 79 74 68 63 58 53 48 42 37 32 5
6 95 90 85 80 75 70 65 60 54 50 44 39 34 6
7 95 90 85 80 76 71 66 61 56 51 47 42 37 7
8 95 91 86 81 76 72 67 62 58 53 49 44 39 8
9 96 91 86 82 77 73 68 64 59 55 51 46 42 9
10 96 91 87 83 78 74 69 65 61 57 52 48 44 10
11 96 92 87 83 79 75 71 66 62 58 54 50 46 11
12 96 92 88 84 80 76 72 68 64 60 56 52 48 12
13 96 92 88 84 81 77 73 69 65 61 58 54 50 13
14 96 93 89 85 81 78 74 70 67 63 59 56 52 14
15 96 93 89 86 82 79 75 71 68 64 61 57 54 15
16 97 93 90 86 83 79 76 73 69 66 62 59 56 16
17 97 93 90 87 83 80 77 74 70 67 64 60 57 17
18 97 94 90 87 84 81 78 74 71 68 65 62 59 18
19 97 94 91 88 84 81 78 75 72 69 66 63 60 19
20 97 94 91 88 85 82 79 76 73 70 67 64 61 20
t.0°.20°.40°.60°.81°.01°.21°.41°.61°.82°.02°.22°.42°.6 t.

Table II.—Relative Humidity, per cent.

t Difference between the dry and wet thermometers (t-t′). t
(Dry ther.) 2°.6 2°.8 3°.0 3°.2 3°.4 3°.6 3°.8 4°.0 4°.2 4°.4(Dry ther.)
-2 7 -2
-1 11 4 -1
0 15 9 0
+1 19 13 7 +1
2 23 17 11 5 2
3 26 20 15 9 4 3
4 29 24 18 13 8 2 4
5 32 27 22 16 11 6 5
6 34 29 25 20 15 10 5 6
7 37 32 28 23 18 13 9 4 7
8 39 35 30 26 21 17 12 8 3 8
9 42 37 33 28 24 20 15 11 7 2 9
10 44 40 35 31 27 23 19 14 10 6 10
11 46 42 38 34 30 26 22 18 14 10 11
12 48 44 40 36 32 28 25 21 17 13 12
13 50 46 42 39 35 31 27 24 20 16 13
14 52 48 45 41 37 34 30 27 23 19 14
15 54 50 47 43 40 36 33 29 26 23 15
16 56 52 49 46 42 39 36 32 29 25 16
17 57 54 51 48 44 41 38 35 31 28 17
18 59 56 53 49 46 43 40 37 34 31 18
19 60 57 54 51 48 45 42 39 36 33 19
20 61 58 56 53 50 47 44 41 38 35 20
t. 2°.6 2°.8 3°.0 3°.2 3°.4 3°.6 3°.8 4°.0 4°.2 4°.4 t.
t. 4°.6 4°.8 5°.0 5°.2 5°.4 5°.6 5°.8 6°.0 6°.2 6°.4 t.
8 8
9 9
10 2 10
11 6 2 11
12 9 5 2 12
13 13 9 5 2 13
14 16 12 9 5 2 14
15 19 16 12 9 5 2 15
16 22 19 16 12 9 6 2 16
17 25 22 19 16 12 9 6 3 17
18 28 25 22 19 16 13 9 6 3 18
19 30 27 24 21 19 16 13 10 7 4 19
20 33 30 27 24 21 19 16 13 10 7 20
t. 4°.6 4°.8 5°.0 5°.2 5°.4 5°.6 5°.8 6°.0 6°.2 6°.4 t.

Table II.—Relative Humidity, Per cent.

t Difference between the dry and wet thermometers (t-t′). t
(Dry ther.) 0°.5 1°.0 1°.5 2°.0 2°.5 3°.0 3°.5 4°.0 4°.5 5°.0 5°.5 6°.0(Dry ther.)
20 92 85 77 70 63 56 48 41 34 27 20 13 20
21 93 85 78 71 64 57 50 43 36 29 23 16 21
22 93 86 79 72 65 58 51 45 38 32 25 19 22
23 93 86 80 73 66 60 53 46 40 34 27 21 23
24 93 87 80 74 67 61 54 48 42 36 30 24 24
25 94 87 81 74 68 62 56 50 44 38 32 26 25
26 94 88 81 75 69 63 57 51 45 40 34 28 26
27 94 88 82 76 70 64 59 53 47 42 36 30 27
28 94 88 82 77 71 65 60 54 49 43 38 33 28
29 94 89 83 77 72 66 61 56 50 45 40 35 29
30 94 89 84 78 73 67 62 57 52 47 41 36 30
31 95 89 84 79 74 68 63 58 53 48 43 38 31
32 95 90 84 79 74 69 64 59 54 50 45 40 32
33 95 90 85 80 75 70 65 60 56 51 47 42 33
34 95 91 86 81 75 72 67 62 57 53 48 44 34
35 95 91 86 82 76 73 69 65 59 54 50 45 35
36 96 91 86 82 77 73 70 66 61 56 51 47 36
37 96 91 87 82 78 74 70 66 62 57 52 48 37
38 96 92 87 83 79 75 71 67 63 58 54 50 38
39 96 92 88 83 79 75 72 68 63 59 55 52 39
40 96 92 88 84 80 76 72 68 64 60 56 53 40
41 96 92 88 84 80 76 72 69 65 61 57 54 41
42 96 92 88 84 81 77 73 69 65 62 58 55 42
43 96 92 88 85 81 77 74 70 66 63 59 56 43
44 96 92 88 85 81 78 74 70 67 63 60 57 44
45 96 92 89 85 82 78 75 71 67 64 61 58 45
46 96 93 89 85 82 79 75 72 68 65 61 58 46
47 96 93 89 86 83 79 76 72 69 66 62 59 47
48 96 93 89 86 83 79 76 73 69 66 63 60 48
49 97 93 90 86 83 80 76 73 70 67 63 60 49
50 97 93 90 87 83 80 77 74 70 67 64 61 50
51 97 93 90 87 84 81 77 74 71 68 65 62 51
52 97 94 90 87 84 81 78 75 72 69 66 63 52
53 97 94 91 87 84 81 78 75 72 69 66 63 53
54 97 94 91 88 85 82 79 76 73 70 67 64 54
55 97 94 91 88 85 82 79 76 73 70 68 65 55
56 97 94 91 88 85 82 80 77 74 71 68 65 56
57 97 94 91 88 86 83 80 77 74 71 69 66 57
58 97 94 91 89 86 83 80 78 75 72 69 67 58
59 97 94 92 89 86 83 81 78 75 72 70 67 59
60 97 94 92 89 86 84 81 78 75 73 70 68 60
61 97 94 92 89 87 84 81 78 76 73 71 68 61
62 97 95 92 89 87 84 81 79 76 74 71 69 62
63 97 95 92 89 87 84 82 79 77 74 72 69 63
64 97 95 92 90 87 85 82 79 77 74 72 70 64
65 97 95 92 90 87 85 82 80 77 75 72 70 65
66 97 95 92 90 87 85 82 80 78 75 73 71 66
67 98 95 93 90 88 85 83 80 78 76 73 71 67
68 98 95 93 90 88 85 83 81 78 76 74 71 68
69 98 95 93 90 88 86 83 81 78 76 74 72 69
70 98 95 93 90 88 86 83 81 79 77 74 72 70
71 98 95 93 91 88 86 84 81 79 77 75 72 71
72 98 95 93 91 88 86 84 82 79 77 75 73 72
73 98 95 93 91 88 86 84 82 80 78 75 73 73
74 98 95 93 91 88 86 84 82 80 78 76 74 74
75 98 95 93 91 89 87 84 82 80 78 76 74 75
76 98 95 93 91 89 87 85 82 80 78 76 74 76
77 98 95 93 91 89 87 85 83 80 78 76 74 77
78 98 96 93 91 89 87 85 83 81 79 77 75 78
79 98 96 94 91 89 87 85 83 81 79 77 75 79
80 98 96 94 92 89 87 85 83 81 79 77 75 80
t. 0°.5 1°.0 1°.5 2°.0 2°.5 3°.0 3°.5 4°.0 4°.5 5°.0 5°.5 6°.0 t.

Table II.—Relative Humidity, per cent.

t Difference between the dry and wet thermometers (t-t′).t
(Dry ther.)6°.06°.57°.07°.58°.08°.59°.09°.510°.010°.511°.011°.512°.0(Dry ther.)
19 10 19
20 13 6 20
21 16 9 2 21
22 19 12 6 22
23 21 15 9 2 23
24 24 17 11 6 24
25 26 20 14 8 3 25
26 28 23 17 11 6 26
27 30 25 19 14 9 3 27
28 33 27 22 17 11 6 1 28
29 35 29 24 19 14 9 4 29
30 36 31 26 22 17 12 7 2 30
31 38 33 29 24 19 14 10 5 31
32 40 35 31 26 21 17 12 8 3 32
33 42 37 33 28 24 19 15 10 6 2 33
34 44 39 35 30 26 21 17 13 9 4 34
35 45 41 37 32 28 24 19 15 12 7 3 35
36 47 43 38 34 30 26 22 18 14 10 6 2 36
37 48 44 40 36 32 28 24 20 16 12 8 5 1 37
38 50 46 42 38 34 30 26 22 18 15 11 7 3 38
39 52 48 44 40 36 32 28 24 20 17 13 9 6 39
40 53 49 45 41 38 34 30 26 22 19 16 12 8 40
41 54 50 46 43 39 36 32 29 24 21 18 14 10 41
42 55 51 48 44 40 37 34 30 27 23 20 16 13 42
43 56 52 49 46 42 38 35 32 29 25 22 19 15 43
44 57 53 50 47 43 40 37 33 30 27 24 21 17 44
45 58 54 51 48 44 41 38 35 32 29 25 22 19 45
46 58 55 52 49 46 42 39 36 33 30 27 23 21 46
47 59 56 53 50 47 44 40 38 34 31 28 25 22 47
48 60 56 53 51 48 45 42 39 36 33 30 27 24 48
49 60 57 54 52 49 46 43 40 37 34 31 29 26 49
50 61 58 55 52 50 47 44 41 38 36 33 30 27 50
51 62 59 56 53 50 48 45 42 39 37 34 31 28 51
52 63 60 57 54 51 48 46 43 40 38 35 33 30 52
53 63 61 58 55 52 49 47 44 42 39 36 34 31 53
54 64 61 59 56 53 50 48 45 43 40 38 35 32 54
55 65 62 59 57 54 51 49 46 43 41 39 36 34 55
56 65 63 60 57 55 52 50 47 44 42 40 37 35 56
57 66 64 61 58 55 53 50 48 45 43 40 38 36 57
58 67 64 61 59 56 53 51 49 46 44 42 39 37 58
59 67 65 62 60 57 54 52 49 47 45 43 40 38 59
60 68 65 63 60 58 55 53 50 48 46 44 41 39 60
61 68 66 63 61 58 56 54 51 49 47 44 42 40 61
62 69 66 64 61 59 57 54 52 50 47 45 43 41 62
63 69 67 64 62 60 57 55 53 51 48 46 44 42 63
64 70 67 65 62 60 58 56 53 51 49 47 45 43 64
65 70 68 65 63 61 59 56 54 52 50 48 46 44 65
66 71 68 66 63 61 59 57 55 53 51 49 47 45 66
67 71 69 66 64 62 60 58 55 53 51 49 47 45 67
68 71 69 67 65 63 60 58 56 54 52 50 48 46 68
69 72 70 67 65 63 61 59 57 55 53 51 49 47 69
70 72 70 68 66 64 62 60 57 55 53 52 50 48 70
71 72 70 68 66 64 62 60 58 56 54 52 50 48 71
72 73 71 69 67 65 63 61 59 57 55 53 51 49 72
73 73 71 69 67 65 63 61 59 57 55 53 52 50 73
74 74 72 70 68 66 64 62 60 58 56 54 52 50 74
75 74 72 70 68 66 64 62 60 58 56 55 53 51 75
76 74 72 70 68 66 64 63 61 59 57 55 53 52 76
77 74 73 71 69 67 65 63 61 59 57 56 54 52 77
78 75 73 71 69 67 65 63 62 60 58 56 54 53 78
79 75 73 71 70 68 66 64 62 60 58 57 55 53 79
80 75 73 72 70 68 66 64 63 61 59 57 55 54 80
t.6°.06°.57°.07°.58°.08°.59°.09°.510°.010°.511°.011°.512°0t.

Table II.—Relative Humidity, per cent.

t Difference between the dry and wet thermometers (t-t′). t
(Dry ther.)12°.012°.513°.013°.514°.014°.515°.015°.516°.016°.517°.017°.518°.0(Dry ther.)
40 8 5 1 40
41 10 7 4 41
42 13 10 6 3 42
43 15 12 9 5 2 43
44 17 14 11 8 5 1 44
45 19 16 13 10 7 4 1 45
46 21 18 15 12 9 6 3 46
47 22 20 16 14 11 8 5 3 47
48 24 21 19 16 13 10 7 5 2 48
49 26 23 20 17 15 12 9 7 4 1 49
50 27 24 22 19 16 14 11 9 6 4 1 50
51 28 26 23 21 18 16 13 10 8 5 3 51
52 30 27 24 22 20 17 15 12 10 7 5 52
53 31 29 26 24 21 19 16 14 12 9 7 4 2 53
54 32 30 28 25 23 20 18 15 13 11 8 6 4 54
55 34 31 29 26 24 22 19 17 15 12 10 8 6 55
56 35 33 30 28 25 23 21 19 16 14 12 10 8 56
57 36 34 32 29 27 24 22 20 18 16 13 11 9 57
58 37 35 33 30 28 26 24 21 19 17 15 13 11 58
59 38 36 34 31 29 27 25 23 21 18 16 14 12 59
60 39 37 34 32 30 28 26 24 22 20 18 16 14 60
61 40 38 35 33 32 29 27 25 23 21 19 17 15 61
62 41 39 37 34 32 30 28 26 24 22 20 18 16 62
63 42 40 38 35 33 31 29 28 26 24 22 20 18 63
64 43 41 38 36 34 32 30 29 27 25 23 21 19 64
65 44 42 39 37 35 33 31 29 28 26 24 22 20 65
66 45 42 40 38 36 34 32 30 29 27 25 23 22 66
67 45 43 41 39 37 35 33 32 30 28 26 25 23 67
68 46 44 42 40 38 36 34 33 31 29 27 26 24 68
69 47 45 43 41 39 37 35 33 32 30 28 26 25 69
70 48 46 44 42 40 38 36 34 33 31 29 27 26 70
71 48 46 45 43 41 39 37 35 34 32 30 28 27 71
72 49 47 45 43 42 40 38 36 35 33 31 30 28 72
73 50 48 46 44 42 41 39 37 35 34 32 30 29 73
74 50 48 47 45 43 41 40 38 36 35 33 31 30 74
75 51 49 47 46 44 42 40 39 37 35 34 32 31 75
76 52 50 48 46 45 43 41 39 38 36 35 33 31 76
77 52 50 49 47 45 44 42 40 39 37 35 34 32 77
78 53 51 49 48 46 44 43 41 39 38 36 35 33 78
79 53 52 50 48 47 45 43 42 40 39 37 36 34 79
80 54 52 51 49 47 45 44 42 41 39 38 36 35 80
t.12°.012°.513°.013°.514°.014°.515°.015°.516°.016°.517°.017°.518°.0 t.

Table II.—Relative Humidity, per cent.

t Difference between the dry and wet thermometers (t-t′). t
(Dry ther.)18°.019°.020°.021°.022°.023°.024°.025°.026°.027°.028°.029°.030°.0(Dry ther.)
55 6 1 55
56 8 3 56
57 9 5 57
58 11 7 2 58
59 12 8 4 59
60 14 10 6 2 60
61 15 11 7 3 61
62 16 13 9 5 1 62
63 18 14 10 7 3 63
64 19 15 12 8 5 1 64
65 20 17 13 10 6 3 65
66 22 18 14 11 8 4 1 66
67 23 19 16 12 9 6 2 67
68 24 20 17 14 10 7 4 1 68
69 25 22 18 15 12 8 5 2 69
70 26 23 19 16 13 10 7 4 1 70
71 27 24 20 17 14 11 8 5 2 71
72 28 24 22 18 15 12 9 6 3 1 72
73 29 25 22 19 16 13 10 8 5 2 73
74 30 26 23 20 18 15 12 9 6 3 1 74
75 31 27 24 21 19 16 13 10 7 5 2 75
76 31 28 25 22 20 17 14 11 8 6 3 1 76
77 32 29 26 23 20 18 15 12 10 7 4 2 77
78 33 30 27 24 21 19 16 13 11 8 6 3 1 78
79 34 31 28 25 22 19 17 14 12 9 7 4 2 79
80 35 32 29 26 23 20 18 15 13 10 8 6 3 80
t.18°.019°.020°.021°.022°.023°.024°.025°.026°.027°.028°.029°.030°.0 t.

Table II.—Relative Humidity, per cent.

t Difference between the dry and wet thermometers (t-t′). t
(Dry ther.) 1°.0 2°.0 3°.0 4°.0 5°.0 6°.0 7°.0 8°.0 9°.010°.011°.012°.0(Dry ther.)
80 96 92 87 83 79 75 72 68 64 61 57 54 80
81 96 92 88 84 80 76 72 68 65 61 58 54 81
82 96 92 88 84 80 76 72 69 65 62 58 55 82
83 96 92 88 84 80 76 73 69 66 62 59 55 83
84 96 92 88 84 80 77 73 69 66 63 59 56 84
85 96 92 88 84 80 77 73 70 66 63 60 56 85
86 96 92 88 84 81 77 73 70 67 63 60 57 86
87 96 92 88 84 81 77 74 70 67 64 60 57 87
88 96 92 88 85 81 77 74 71 67 64 61 58 88
89 96 92 88 85 81 78 74 71 68 64 61 58 89
90 96 92 88 85 81 78 75 71 68 65 62 59 90
91 96 92 89 85 82 78 75 71 68 65 62 59 91
92 96 92 89 85 82 78 75 72 69 65 62 59 92
93 96 93 89 85 82 78 75 72 69 66 63 60 93
94 96 93 89 86 82 79 75 72 69 66 63 60 94
95 96 93 89 86 82 79 76 72 69 66 63 60 95
96 96 93 89 86 82 79 76 73 70 67 64 61 96
97 96 93 89 86 82 79 76 73 70 67 64 61 97
98 96 93 89 86 83 79 76 73 70 67 64 61 98
99 96 93 89 86 83 80 76 73 70 68 65 62 99
100 97 93 90 86 83 80 77 74 71 68 65 62 100
101 97 93 90 86 83 80 77 74 71 68 65 62 101
102 97 93 90 86 83 80 77 74 71 68 65 63 102
103 97 93 90 87 83 80 77 74 71 69 66 63 103
104 97 93 90 87 83 80 77 74 72 69 66 63 104
105 97 93 90 87 84 81 78 75 72 69 66 64 105
106 97 93 90 87 84 81 78 75 72 69 66 64 106
107 97 93 90 87 84 81 78 75 72 69 67 64 107
108 97 93 90 87 84 81 78 75 72 70 67 64 108
109 97 93 90 87 84 81 78 75 73 70 67 65 109
110 97 94 90 87 84 81 78 76 73 70 67 65 110
t. 1°.0 2°.0 3°.0 4°.0 5°.0 6°.0 7°.0 8°.0 9°.010°.011°.012°.0 t.

Table II.—Relative Humidity, per cent.

t Difference between the dry and wet thermometers (t-t′). t
(Dry ther.)12°.013°.014°.015°.016°.017°.018°.019°.020°.021°.022°.023°.024°.0(Dry ther.)
80 54 51 47 44 41 38 35 32 29 26 23 20 18 80
81 54 51 48 44 41 38 35 33 30 27 24 21 19 81
82 55 52 48 45 42 39 36 33 31 28 25 22 20 82
83 55 52 49 46 43 40 37 34 31 29 26 23 21 83
84 56 53 49 46 44 41 38 35 32 29 27 24 22 84
85 56 53 50 47 44 41 38 36 33 30 28 25 22 85
86 57 54 51 48 45 42 39 36 34 31 29 26 23 86
87 57 54 51 48 45 42 40 37 34 32 30 27 24 87
88 58 55 52 49 46 43 40 38 35 32 30 27 25 88
89 58 55 52 49 46 44 41 38 36 33 31 28 26 89
90 59 56 53 50 47 44 41 39 36 34 32 29 26 90
91 59 56 53 50 47 45 42 39 37 35 33 30 27 91
92 59 56 54 51 48 45 43 40 37 35 33 30 28 92
93 60 57 54 51 48 46 43 41 38 36 34 31 29 93
94 60 57 54 52 49 46 44 41 39 36 34 31 29 94
95 60 58 55 52 49 47 44 42 39 37 35 32 30 95
96 61 58 55 53 50 47 45 42 40 37 36 33 30 96
97 61 58 56 53 50 48 45 43 40 38 36 33 31 97
98 61 59 56 53 51 48 46 43 41 38 37 34 32 98
99 62 59 56 54 51 49 46 44 41 39 37 34 32 99
100 62 59 57 54 51 49 47 44 42 39 37 35 33 100
101 62 60 57 54 52 49 47 45 42 40 38 36 33 101
102 63 60 57 55 52 50 47 45 43 40 38 36 34 102
103 63 60 58 55 53 50 48 45 43 41 39 37 34 103
104 63 61 58 55 53 51 48 46 44 41 39 37 35 104
105 64 61 58 56 53 51 49 46 44 42 40 38 35 105
106 64 61 59 56 54 51 49 47 44 42 40 38 36 106
107 64 62 59 57 54 52 49 47 45 43 41 38 36 107
108 64 62 59 57 54 52 50 47 45 43 41 39 37 108
109 65 62 60 57 55 52 50 48 46 44 41 39 37 109
110 65 62 60 57 55 53 50 48 46 44 42 40 38 110
t.12°.013°.014°.015°.016°.017°.018°.019°.020°.021°.022°.023°.024°.0 t.

Table II.—Relative Humidity, per cent.

t Difference between the dry and wet thermometers (t-t′). t
(Dry ther.)24°.025°.026°.027°.028°.029°.030°.031°.032°.033°.034°.035°.036°.0(Dry ther.)
80 18 15 13 10 8 6 3 1 80
81 19 16 14 11 9 7 4 2 81
82 20 17 15 12 10 8 5 3 1 82
83 21 18 16 13 11 9 6 4 2 83
84 22 19 17 14 12 10 8 5 3 1 84
85 22 20 17 15 13 11 9 6 4 2 85
86 23 21 18 16 14 12 10 7 5 3 1 86
87 24 22 19 17 15 13 11 8 6 4 2 87
88 25 22 20 18 16 14 12 9 7 5 3 1 88
89 26 23 21 19 16 14 12 10 8 6 4 2 1 89
90 26 24 22 20 17 15 13 11 9 7 5 3 2 90
91 27 25 23 20 18 16 14 12 10 8 6 4 3 91
92 28 26 23 21 19 17 15 13 11 9 7 5 3 92
93 29 26 24 22 20 18 16 14 12 10 8 6 4 93
94 29 27 25 23 21 18 16 14 13 11 9 7 5 94
95 30 28 25 23 21 19 17 15 13 11 10 8 6 95
96 30 28 26 24 22 20 18 16 14 12 10 9 7 96
97 31 29 27 25 23 21 19 17 15 13 11 10 8 97
98 32 29 27 25 23 21 19 18 16 14 12 10 9 98
99 32 30 28 26 24 22 20 18 16 15 13 11 10 99
100 33 31 29 27 25 23 21 19 17 15 14 12 10 100
101 33 31 29 27 25 23 21 20 18 16 14 13 11 101
102 34 32 30 28 26 24 22 20 19 17 15 13 12 102
103 34 32 30 28 26 25 23 21 19 17 16 14 12 103
104 35 33 31 29 27 25 23 22 20 18 16 15 13 104
105 35 33 31 30 28 26 24 22 20 19 17 15 14 105
106 36 34 32 30 28 26 25 23 21 19 18 16 14 106
107 36 34 32 31 29 27 25 23 22 20 18 17 15 107
108 37 35 33 31 29 27 26 24 22 21 19 17 16 108
109 37 35 33 32 30 28 26 25 23 21 20 18 16 109
110 38 36 34 32 30 28 27 25 23 22 20 19 17 110
t.24°.025°.026°.027°.028°.029°.030°.031°.032°.033°.034°.035°.036°.0 t.

Table II.—Relative Humidity, per cent.

t Difference between the dry and wet thermometers (t-t′). t
(Dry ther.)36°.037°.038°.039°.040°.041°.042°.043°.044°.045°.046°.048°.0(Dry ther.)
89 1 89
90 2 90
91 3 1 91
92 3 2 1 92
93 4 3 2 93
94 5 4 3 0 94
95 6 5 4 1 95
96 7 5 5 2 1 96
97 8 6 6 3 1 97
98 9 7 7 4 2 1 98
99 10 8 7 5 3 2 0 99
100 10 9 8 6 4 3 1 100
101 11 9 9 6 5 3 2 0 101
102 12 10 9 7 6 4 3 1 102
103 12 11 9 8 6 5 4 2 1 103
104 13 12 10 8 7 6 5 3 2 104
105 14 12 11 9 8 6 5 4 2 1 105
106 14 13 11 10 8 7 6 4 3 2 0 106
107 15 14 12 11 9 8 6 5 4 3 1 107
108 16 14 13 11 10 9 7 6 5 3 2 108
109 16 15 13 12 10 9 8 7 5 4 3 109
110 17 15 14 13 11 10 8 7 6 5 3 1 110
t.36°.037°.038°.039°.040°.041°.042°.043°.044°.045°.046°.048°.0 t.

Table III.—Reduction of Barometer Reading to 32°.

Inches.
Temperature
°F		 24.0 24.5 25.0 25.5 26.0 26.5 27.0 27.5 28.0 28.5 29.0 29.5 30.0 30.5 31.0
30-.003-.003-.003-.003-.003-.003-.003-.003-.003-.004-.004-.004-.004-.004-.004
31 .005 .005 .005 .005 .006 .006 .006 .006 .006 .006 .006 .006 .006 .007 .007
32 .007 .008 .008 .008 .008 .008 .008 .008 .009 .009 .009 .009 .009 .009 .009
33 .010 .010 .010 .010 .010 .010 .011 .011 .011 .011 .012 .012 .012 .012 .012
34 .012 .012 .012 .012 .013 .013 .013 .013 .014 .014 .014 .014 .015 .015 .015
35 .014 .014 .014 .015 .015 .015 .016 .016 .016 .016 .017 .017 .017 .018 .018
36 .016 .016 .017 .017 .017 .018 .018 .018 .019 .019 .019 .020 .020 .020 .021
37 .018 .019 .019 .019 .020 .020 .021 .021 .021 .022 .022 .022 .023 .023 .024
38 .020 .021 .021 .022 .022 .022 .023 .023 .024 .024 .025 .025 .026 .026 .026
39 .023 .023 .024 .024 .024 .025 .025 .026 .026 .027 .027 .028 .028 .029 .029
40 .025 .025 .026 .026 .027 .027 .028 .028 .029 .030 .030 .030 .031 .031 .032
41 .027 .027 .028 .029 .029 .030 .030 .031 .031 .032 .033 .033 .034 .034 .035
42 .029 .030 .030 .031 .032 .032 .033 .033 .034 .034 .035 .036 .036 .037 .038
43 .031 .032 .033 .033 .034 .035 .035 .036 .036 .037 .038 .038 .039 .040 .040
44 .033 .034 .035 .035 .036 .037 .038 .038 .039 .040 .040 .041 .042 .042 .043
45 .036 .037 .037 .038 .039 .039 .040 .041 .042 .042 .043 .044 .045 .045 .046
46 .038 .038 .039 .040 .041 .042 .043 .043 .044 .045 .046 .046 .047 .048 .049
47 .040 .041 .042 .042 .043 .044 .045 .046 .047 .048 .048 .049 .050 .051 .052
48 .042 .043 .044 .045 .046 .047 .047 .048 .049 .050 .051 .052 .053 .053 .054
49 .044 .045 .046 .047 .048 .049 .050 .051 .052 .052 .054 .054 .055 .056 .057
50 .046 .047 .048 .049 .050 .051 .052 .053 .054 .055 .056 .057 .058 .059 .060
51 .049 .050 .051 .052 .053 .054 .055 .056 .057 .058 .059 .060 .061 .062 .063
52 .051 .052 .053 .054 .055 .056 .057 .058 .059 .060 .061 .062 .064 .065 .066
53 .053 .054 .055 .056 .057 .058 .060 .061 .062 .063 .064 .065 .066 .067 .068
54 .055 .056 .057 .058 .060 .061 .062 .063 .064 .065 .067 .068 .069 .070 .071
55 .057 .058 .060 .061 .062 .063 .064 .065 .066 .068 .069 .070 .071 .073 .074
56 .060 .061 .062 .063 .064 .065 .067 .068 .069 .070 .072 .073 .074 .075 .077
57 .062 .063 .064 .065 .067 .068 .069 .070 .072 .073 .075 .076 .077 .078 .080
58 .064 .065 .066 .068 .069 .070 .071 .073 .074 .076 .077 .078 .080 .081 .082
59 .066 .068 .069 .070 .072 .073 .074 .075 .077 .078 .080 .081 .083 .084 .085
60 .068 .070 .071 .072 .074 .076 .077 .078 .079 .081 .082 .084 .085 .086 .088
61 .070 .072 .073 .074 .076 .077 .079 .080 .082 .083 .085 .086 .088 .089 .091
62 .073 .074 .076 .077 .079 .080 .082 .083 .085 .086 .088 .089 .091 .092 .094
63 .075 .076 .078 .079 .081 .082 .084 .085 .087 .088 .090 .091 .093 .095 .096
64 .077 .078 .080 .081 .083 .085 .086 .088 .090 .091 .093 .094 .096 .097 .099
65-.079-.080-.082-.084-.086-.087-.089-.090-.092-.093-.095-.097-.099-.100-.102

Table III.—Reduction of Barometer Reading to 32°.—Continued.

Inches.
°F 24.0 24.5 25.0 25.5 26.0 26.5 27.0 27.5 28.0 28.5 29.0 29.5 30.0 30.5 31.0
65-.079-.080-.082-.084-.086-.087-.089-.090-.092-.093-.095-.097-.099-.100-.102
66 .081 .083 .085 .086 .088 .089 .091 .093 .095 .096 .098 .099 .101 .103 .105
67 .083 .085 .087 .088 .090 .092 .094 .095 .097 .099 .101 .102 .104 .106 .108
68 .085 .087 .089 .090 .093 .094 .096 .098 .100 .101 .103 .105 .107 .108 .110
69 .088 .089 .091 .093 .095 .097 .099 .100 .102 .104 .106 .107 .110 .111 .113
70 .090 .092 .094 .096 .097 .099 .101 .103 .105 .106 .109 .110 .112 .114 .116
71 .092 .094 .096 .098 .100 .101 .103 .105 .107 .109 .111 .113 .115 .116 .119
72 .094 .096 .098 .100 .102 .104 .106 .108 .110 .112 .114 .116 .118 .120 .122
73 .096 .098 .100 .102 .104 .106 .108 .110 .112 .114 .116 .118 .120 .122 .124
74 .098 .100 .103 .105 .107 .109 .111 .113 .115 .117 .119 .121 .123 .125 .127
75 .101 .102 .105 .106 .109 .111 .113 .115 .117 .119 .122 .124 .126 .128 .130
76 .103 .104 .107 .109 .111 .113 .116 .118 .120 .122 .124 .126 .128 .130 .133
77 .105 .107 .109 .111 .114 .116 .118 .120 .122 .124 .127 .129 .131 .133 .136
78 .107 .109 .112 .113 .116 .118 .120 .122 .125 .127 .129 .131 .134 .136 .138
79 .109 .111 .114 .116 .118 .120 .123 .125 .127 .129 .132 .134 .137 .139 .141
80 .111 .113 .116 .118 .121 .123 .125 .127 .130 .132 .135 .137 .139 .141 .144
81 .114 .116 .118 .120 .123 .125 .128 .130 .132 .134 .137 .139 .142 .144 .147
82 .116 .118 .121 .122 .125 .128 .130 .132 .135 .137 .140 .142 .145 .147 .149
83 .118 .120 .123 .125 .128 .130 .133 .135 .138 .140 .142 .145 .147 .149 .152
84 .120 .122 .125 .127 .130 .132 .135 .138 .140 .142 .145 .147 .150 .152 .155
85 .122 .124 .127 .129 .132 .134 .137 .139 .143 .145 .148 .150 .153 .155 .158
86 .124 .126 .128 .130 .135 .137 .140 .143 .145 .148 .150 .153 .155 .158 .161
87 .126 .129 .132 .134 .137 .139 .142 .144 .148 .150 .153 .155 .158 .161 .163
88 .129 .131 .134 .137 .139 .142 .145 .147 .150 .152 .155 .158 .161 .163 .166
89 .131 .133 .136 .139 .142 .144 .147 .150 .153 .155 .158 .161 .164 .166 .169
90 .133 .136 .138 .141 .144 .147 .150 .153 .155 .157 .161 .164 .166 .169 .172
91 .135 .138 .141 .143 .146 .149 .152 .155 .158 .160 .163 .166 .169 .172 .175
92 .137 .140 .143 .146 .149 .152 .154 .157 .160 .163 .166 .169 .172 .175 .177
93 .139 .142 .145 .148 .151 .154 .157 .160 .163 .166 .168 .171 .174 .177 .180
94 .142 .145 .147 .150 .153 .156 .159 .162 .165 .168 .171 .174 .177 .180 .183
95 .144 .147 .150 .153 .156 .159 .162 .165 .168 .171 .174 .177 .180 .183 .186
96 .146 .149 .152 .155 .158 .161 .164 .167 .170 .173 .176 .179 .182 .185 .188
97 .148 .151 .154 .157 .160 .164 .167 .170 .173 .176 .179 .182 .185 .188 .191
98 .150 .153 .156 .160 .163 .166 .169 .172 .175 .178 .181 .185 .188 .191 .194
99 .152 .155 .159 .162 .165 .168 .171 .175 .178 .181 .184 .187 .190 .194 .197
100-.154-.157-.161-.164-.167-.171-.174-.177-.180-.184-.187-.190-.193-.197-.200

Table IV.—Table for Reducing Observations of the Barometer to
Sea Level, Correction Additive.

Height, in feet. Temperature of external air—degrees Fahrenheit.
-20° -10° 0° 10° 20° 30° 40° 50° 60° 70° 80° 90° 100°
10 .013 .013 .012 .012 .012 .012 .011 .011 .011 .011 .010 .010 .010
20 .026 .025 .025 .024 .023 .023 .023 .022 .022 .021 .021 .020 .020
30 .039 .038 .037 .036 .035 .034 .034 .033 .032 .032 .031 .030 .030
40 .052 .050 .049 .048 .047 .046 .045 .044 .043 .042 .041 .040 .040
50 .065 .063 .061 .060 .059 .058 .056 .055 .054 .053 .052 .051 .050
60 .077 .076 .074 .072 .070 .069 .068 .066 .065 .063 .062 .061 .059
70 .090 .088 .086 .084 .082 .081 .078 .077 .076 .074 .072 .071 .069
80 .103 .101 .098 .096 .094 .092 .090 .088 .086 .084 .082 .081 .079
90 .116 .113 .111 .108 .105 .104 .101 .099 .097 .095 .093 .091 .089
100 .129 .126 .123 .120 .117 .115 .112 .110 .108 .105 .103 .101 .099
110 .142 .139 .135 .132 .129 .126 .123 .121 .119 .116 .113 .111 .109
120 .155 .151 .148 .144 .140 .138 .134 .132 .129 .126 .124 .121 .119
130 .168 .164 .160 .156 .152 .149 .146 .143 .140 .137 .134 .131 .129
140 .181 .176 .172 .168 .164 .161 .157 .154 .151 .147 .144 .141 .139
150 .194 .189 .185 .180 .176 .172 .168 .165 .162 .158 .155 .152 .149
160 .206 .201 .197 .192 .187 .183 .179 .176 .172 .168 .165 .162 .158
170 .219 .214 .209 .204 .199 .195 .190 .187 .183 .179 .175 .172 .168
180 .232 .227 .222 .216 .211 .206 .202 .198 .194 .189 .185 .182 .178
190 .245 .239 .234 .228 .222 .218 .213 .209 .204 .200 .196 .192 .188
200 .258 .252 .246 .240 .234 .229 .224 .220 .215 .210 .206 .202 .198
210 .271 .264 .258 .252 .246 .240 .235 .231 .226 .221 .216 .212 .208
220 .284 .277 .270 .264 .257 .252 .246 .242 .236 .231 .227 .222 .218
230 .296 .289 .283 .276 .269 .263 .257 .253 .247 .242 .237 .232 .228
240 .309 .302 .295 .288 .281 .275 .269 .264 .258 .252 .248 .242 .238
250 .322 .314 .307 .300 .293 .286 .280 .275 .269 .263 .258 .253 .248
260 .335 .327 .319 .311 .304 .297 .291 .285 .279 .273 .268 .263 .257
270 .348 .339 .331 .323 .316 .309 .302 .296 .290 .284 .278 .273 .267
280 .360 .352 .344 .335 .328 .320 .314 .307 .301 .294 .288 .283 .277
290 .373 .364 .356 .347 .339 .332 .325 .318 .311 .305 .299 .293 .287
300 .386 .377 .368 .359 .351 .343 .336 .329 .322 .315 .309 .303 .297
310 .399 .389 .380 .371 .363 .354 .347 .340 .333 .326 .319 .313 .307
320 .412 .402 .392 .383 .374 .366 .358 .351 .343 .336 .329 .323 .317
330 .424 .414 .404 .395 .386 .377 .369 .362 .354 .347 .340 .333 .326
340 .437 .427 .416 .407 .397 .389 .380 .373 .365 .357 .350 .343 .336
350 .450 .439 .429 .419 .409 .400 .392 .384 .376 .368 .360 .353 .346
360 .463 .451 .441 .430 .421 .411 .403 .394 .386 .378 .370 .363 .356
370 .476 .464 .453 .442 .432 .423 .414 .405 .397 .389 .380 .373 .366
380 .488 .476 .465 .454 .444 .434 .425 .416 .408 .399 .391 .383 .375
390 .501 .489 .477 .466 .455 .446 .436 .427 .418 .410 .401 .393 .385
400 .514 .501 .489 .478 .467 .457 .447 .438 .429 .420 .411 .403 .395
410 .527 .513 .501 .490 .479 .468 .458 .449 .440 .430 .421 .413 .405
420 .539 .526 .513 .502 .490 .480 .469 .460 .450 .441 .431 .423 .415
430 .552 .538 .525 .513 .502 .491 .480 .470 .461 .451 .442 .433 .425
440 .565 .551 .537 .525 .513 .502 .491 .481 .471 .462 .452 .443 .434
450 .578 .563 .550 .537 .525 .513 .503 .492 .482 .472 .462 .453 .444
460 .590 .575 .562 .549 .537 .525 .514 .503 .493 .482 .472 .463 .454
470 .603 .588 .574 .561 .548 .536 .525 .514 .503 .493 .482 .473 .464
480 .616 .600 .586 .572 .560 .547 .536 .524 .514 .503 .493 .483 .474
490 .628 .613 .598 .584 .571 .559 .547 .535 .524 .514 .503 .493 .483
500 .641 .625 .610 .596 .583 .570 .558 .546 .535 .524 .513 .503 .493
510 .654 .637 .622 .608 .594 .581 .569 .557 .545 .534 .523 .513 .503
520 .666 .650 .634 .620 .606 .593 .580 .568 .556 .545 .533 .523 .513
530 .679 .662 .646 .631 .617 .604 .591 .578 .566 .555 .544 .533 .522
540 .691 .675 .658 .643 .629 .615 .602 .589 .577 .565 .554 .543 .532

Table IV.—For Reducing Observations of the Barometer to Sea
Level.—Continued.

Height, in feet. Temperature of external air—degrees Fahrenheit.
-20° -10° 0° 10° 20° 30° 40° 50° 60° 70° 80° 90° 100°
550 .704 .687 .670 .655 .640 .626 .613 .600 .587 .575 .564 .553 .542
560 .717 .699 .683 .667 .652 .638 .624 .611 .598 .586 .574 .563 .552
570 .729 .712 .695 .679 .663 .649 .635 .622 .608 .596 .584 .573 .562
580 .742 .724 .707 .690 .675 .660 .646 .632 .619 .606 .595 .583 .571
590 .754 .737 .719 .702 .686 .672 .657 .643 .629 .617 .605 .593 .581
600 .767 .749 .731 .714 .698 .683 .668 .654 .640 .627 .615 .603 .591
610 .780 .761 .743 .726 .709 .694 .679 .665 .650 .637 .625 .613 .601
620 .792 .774 .755 .738 .721 .705 .690 .675 .661 .648 .635 .623 .611
630 .805 .786 .767 .749 .732 .717 .701 .686 .671 .658 .645 .633 .620
640 .817 .798 .779 .761 .744 .728 .712 .697 .682 .668 .655 .643 .630
650 .830 .811 .791 .773 .755 .739 .723 .708 .692 .679 .666 .653 .640
660 .843 .823 .803 .785 .767 .750 .734 .718 .703 .689 .676 .662 .650
670 .855 .835 .815 .797 .778 .761 .745 .729 .713 .699 .686 .672 .660
680 .868 .847 .827 .808 .790 .773 .756 .740 .724 .709 .696 .682 .669
690 .880 .860 .839 .820 .801 .784 .767 .750 .734 .720 .706 .692 .679
700 .893 .872 .851 .832 .813 .795 .778 .761 .745 .730 .716 .702 .689
710 .905 .884 .863 .844 .824 .806 .789 .772 .755 .740 .726 .712 .698
720 .918 .896 .875 .855 .836 .817 .800 .782 .766 .751 .736 .722 .708
730 .930 .909 .887 .867 .847 .829 .811 .793 .776 .761 .746 .732 .718
740 .943 .921 .899 .879 .859 .840 .822 .804 .787 .771 .756 .742 .728
750 .955 .933 .911 .891 .870 .851 .833 .815 .797 .782 .767 .752 .738
760 .968 .945 .922 .902 .881 .862 .843 .825 .808 .792 .777 .761 .747
770 .980 .957 .934 .914 .893 .873 .854 .836 .818 .802 .787 .771 .757
780 .993 .970 .946 .926 .904 .885 .865 .847 .829 .812 .797 .781 .767
7901.005 .982 .958 .937 .916 .896 .876 .857 .839 .823 .807 .791 .776
8001.018 .994 .970 .949 .927 .907 .887 .868 .850 .833 .817 .801 .786
8101.0301.006 .982 .961 .938 .918 .898 .878 .860 .843 .827 .811 .796
8201.0431.018 .994 .972 .950 .929 .909 .889 .871 .854 .937 .821 .805
8301.0551.0311.006 .984 .961 .940 .920 .900 .881 .864 .847 .831 .815
8401.0681.0431.018 .995 .973 .951 .931 .911 .892 .874 .857 .841 .825
8501.0801.0551.0301.007 .984 .962 .942 .922 .902 .885 .867 .851 .835
8601.0931.0671.0411.019 .995 .974 .952 .932 .913 .895 .877 .860 .844
8701.1051.0791.0531.0301.007 .985 .963 .943 .923 .905 .887 .870 .854
8801.1181.0921.0651.0421.018 .996 .974 .954 .934 .915 .897 .880 .864
8901.1301.1041.0771.0531.0301.007 .985 .904 .944 .926 .907 .890 .873
9001.1431.1161.0891.0651.0411.018 .996 .975 .955 .936 .917 .900 .883
9101.1551.1281.1011.0771.0521.0291.007 .986 .965 .946 .927 .910 .893
9201.1681.1401.1131.0881.0641.0401.018 .996 .976 .956 .937 .920 .902
9301.1801.1521.1251.1001.0751.0511.0291.007 .986 .967 .947 .929 .912
9401.1931.1641.1371.1111.0861.0621.0401.017 .997 .977 .957 .939 .921
9501.2051.1771.1491.1231.0981.0741.0511.0281.007 .987 .967 .949 .931
9601.2171.1891.1601.1351.1091.0851.0611.0391.017 .997 .977 .959 .941
9701.2301.2011.1721.1461.1201.0961.0721.0491.0281.007 .987 .969 .950
9801.2421.2131.1841.1581.1311.1071.0831.0601.0381.018 .997 .978 .960
9901.2551.2251.1961.1691.1431.1181.0941.0701.0491.0281.007 .988 .969
10001.2671.2371.2081.1811.1541.1291.1051.0811.0591.0381.017 .998 .979
10101.2791.2491.2201.1921.1651.1401.1161.0921.0691.0481.0271.008 .989
10201.2921.2611.2321.2041.1771.1511.1271.1021.0801.0581.0371.018 .998
10301.3041.2731.2431.2151.1881.1621.1371.1131.0901.0691.0471.0271.008
10401.3171.2851.2551.2271.1991.1731.1481.1231.1011.0791.0571.0371.017
10501.3291.2981.2671.2381.2111.1841.1591.1341.1111.0891.0671.0471.027
10601.3411.3101.2791.2501.2221.1951.1701.1451.1211.0991.0771.0571.037
10701.3541.3221.2911.2611.2331.2061.1811.1551.1321.1091.0871.0671.046
10801.3661.3341.3021.2731.2441.2171.1911.1661.1421.1201.0971.0761.056
10901.3791.3461.3141.2841.2561.2281.2021.1761.1531.1301.1071.0861.065

Table IV.—For Reducing Observations of the Barometer to Sea
Level.—Continued.

Height, in feet. Temperature of external air—degrees Fahrenheit.
-20° -10° 0° 10° 20° 30° 40° 50° 60° 70° 80° 90° 100°
11001.3911.3581.3261.2961.2671.2391.2131.1871.1631.1401.1171.0961.075
11101.4031.3701.3381.3071.2781.2501.2241.1981.1731.1501.1271.1061.085
11201.4161.3821.3501.3191.2891.2611.2351.2081.1841.1601.1371.1151.094
11301.4281.3941.3611.3301.3011.2721.2451.2191.1941.1701.1471.1251.104
11401.4401.4061.3731.3421.3121.2831.2561.2291.2041.1801.1571.1351.113
11501.4531.4181.3851.3531.3231.2941.2671.2401.2151.1911.1671.1451.123
11601.4651.4301.3971.3651.3341.3051.2781.2511.2251.2011.1771.1541.133
11701.4771.4421.4091.3761.3451.3151.2891.2611.2351.2111.1871.1641.142
11801.4891.4541.4201.3881.3571.3271.2991.2721.2451.2211.1971.1741.152
11901.5021.4661.4321.3991.3681.3381.3101.2821.2561.2311.2071.1831.161
12001.5141.4781.4441.4111.3791.3491.3211.2931.2661.2411.2171.1931.171
12101.5261.4901.4561.4221.3901.3601.3321.3031.2761.2511.2271.2031.180
12201.5391.5021.4671.4341.4011.3711.3421.3141.2881.2611.2371.2121.190
12301.5511.5141.4791.4451.4131.3821.3531.3241.2971.2711.2471.2221.199
12401.5631.5261.4911.4571.4241.3931.3641.3351.3071.2811.2571.2321.209
12501.5761.5381.5021.4681.4351.4041.3741.3451.3171.2911.2661.2421.218
12601.5881.5501.5141.4791.4461.4151.3851.3561.3281.3021.2761.2511.228
12701.6001.5621.5261.4911.4571.4261.3961.3661.3381.3121.2861.2611.237
12801.6121.5741.5381.5021.4691.4371.4071.3771.3481.3221.2961.2711.247
12901.6251.5861.5491.5141.4801.4481.4171.3871.3591.3321.3061.2801.256
13001.6371.5981.5611.5251.4911.4591.4281.3981.3691.3421.3161.2901.266
13101.6491.6101.5731.5361.5021.4701.4391.4081.3791.3521.3261.3001.275
13201.6611.6221.5841.5481.5131.4811.4491.4191.3901.3621.3361.3091.285
13301.6741.6341.5961.5591.5251.4921.4601.4291.4001.3721.3461.3191.294
13401.6861.6401.6081.5711.5361.5031.4711.4401.4101.3821.3561.3291.304
13501.6981.6581.6201.5821.5471.5141.4821.4501.4201.3931.3661.3391.313
13601.7101.6691.6311.5931.5581.5241.4921.4611.4311.4031.3751.3481.323
18701.7221.6811.6431.6051.5691.5351.5031.4711.4411.4131.3851.3581.332
13801.7351.6931.6551.6161.5811.5461.5141.4821.4511.4231.3951.3681.342
13901.7471.7051.6661.6281.5921.5571.5241.4921.4621.4331.4051.3771.351
14001.7591.7171.6781.6391.6031.5681.5351.5031.4721.4431.4151.3871.361
14101.7711.7291.6901.6501.6141.5791.5461.5131.4821.4531.4251.3971.370
14201.7831.7411.7011.6621.6251.5901.5561.5241.4921.4631.4351.4061.380
14301.7961.7531.7131.6731.6361.6011.5671.5341.5031.4731.4441.4161.389
14401.8081.7651.7241.6851.0471.6121.5771.5451.5131.4831.4541.4261.399
14501.8201.7771.7361.6961.6581.6231.5881.5551.5231.4931.4641.4361.408
14601.8321.7881.7481.7071.6701.6331.5991.5651.5331.5031.4741.4451.418
14701.8441.8001.7591.7191.0811.6441.6091.5761.5431.5131.4841.4551.427
14801.8571.8121.7711.7301.6921.6551.6201.5861.5541.5231.4931.4651.437
14901.8691.8241.7821.7421.7031.6661.6301.5971.5641.5331.5031.4741.446
15001.8811.8361.7941.7531.7141.6771.6411.6071.5741.5431.5131.4841.456