Handbook of Meteorology/Appendix

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Handbook of Meteorology
by Jacques Wardlaw Redway

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3687491Handbook of Meteorology — AppendixJacques Wardlaw Redway

APPENDIX

REFERENCE TABLES

C. G. S. UNITS

The construction and evolution of the system of electrical units now in general use began in Europe where the metric system originated. Two of the basic units, the centimeter and the gram, are metric units; the second of time is universally employed in time measurements.

The meter, 3.2808 feet = 39.37 inches, is theoretically the one ten-millionth part of the earth’s quadrant; actually it is the length of a metal rod differing from the theoretical value by about three-fourths of a millimeter. The prefixed multiples, deka-, hecto-, kilo- and mega- are in ten-fold ratio. They indicate respectively 10, 100, 1000 and 1,000,000. The prefixed decimal divisions, deci-, centi-, milli- and micro- indicate tenths, hundredths, thousandths and millionths.

The C. G. S. units are generally used in the United States in chemical and in abstract physical determinations. On account of their inconvenient magnitudes their use has not extended to mechanics; and for this reason the employment of them is strenuously resisted by manufacturers in every line.

Units of the C. G. S. System. — The centimeter, the one-hundredth part of the meter, is the unit of length. 1 cm = 0.0328 foot.

The gram, the unit of mass, is the weight of 1 cu cm of pure water under standard conditions. 1 g = 0.0022 pound = 15.432 grains. The weight of a cubic centimeter of a substance also represents its specific gravity.

The square centimeter is the unit of area. 1 sq cm or cm₂ = 0.001076 sq ft = 0.1 550 sq in.

The cubic centimeter is the unit of volume. 1 cc = 0.0000353 cu ft = 0.061 cu in.

The unit of density is numerically the same as the specific gravity. It is the rate of 1 gram per cubic centimeter.

The unit of velocity is the velocity of 1 centimeter per second; 1 cm per second = 0.0328 foot per second = 0.0224 m. per hour.

The unit of acceleration is the rate of a unit of velocity per second or 1 centimeter per second, per second.

The unit of force, 1 dyne, is the force which imparts to 1 gram a velocity of 1 centimeter per second, per second. It is sometimes expressed in the term poundals; 1 dyne = 0.0000722 poundal. The acceleration of gravity of a falling body varies in different latitudes because the earth is spheroidal and not globular in form. In latitude 45° , the latitude to which results commonly are reduced, the acceleration is 980.621 centimeters per second, per second. If the relative value at latitude 45° be taken as a unit, the relative value at the equator will be 0.9974; at the pole 1.0027.

The unit of pressure is 1 dyne per square centimeter. The megadyne is a more convenient unit and generally is used. The megadyne is commonly called 1 bar. Barometric pressure is read in kilobars and its subdivisions in millibars. 1 bar = 1000 millibars = 0.001 kilobar. 1 kilobar = 0.03386 inch; 1 inch = 33.864 millibars; 1 millimeter = 1.333 millibars. The barometric pressure at 29.53 inches =1000 millibars, which is equivalent to an altitude of 338 feet above mean sea level. The dyne may be conceived as the pressure upon the hand—that is, the weight—of a piece of very thin tissue paper 1 centimeter square.

The unit of rainfall is 1 millimeter. For all practical purposes, the reduction of hundredths of an inch in rainfall to millimeters of rainfall is effected, by moving the decimal point two places to the right and dividing by 4. Thus, if the catchment of a storm is 2.40 inches; the division gives 60 millimeters. A more accurate result will be obtained by using 3.94 as the divisor. Multiplying by .04 reduces millimeters of rainfall to inches of rainfall.

The practical unit of wind velocity is 1 meter per second—that is, 100 times the C. G. S. unit.

The practical unit of wind force is 1 kilodyne per unit of area.

The practical unit of wind pressure is the millibar. Wind force is not always exactly proportional to the area.

The practical unit of radiation is the gram calorie (in distinction from the great calorie) or the warmth required to raise 1 gram of water 1° C in temperature.

The erg, the unit of work, is the amount of work done when a mass of 1 gram moves a distance of 1 centimeter, against a resistance of 1 dyne. A more practical unit is the joule, or 10,000,000 ergs.

The unit of time is the second, of which the mean solar day contains 86,400.

Units of Magnetism and Electricity.—Magnetism may be either positive or negative. Bodies charged with the same kind of magnetism repel each other; charged with opposite kinds, they attract. Commercial magnets are usually marked, the letter N or a dash being stamped upon the north-seeking pole. The convenient unit of magnetism is one which attracts or repels an equal quantity at a distance of 1 centimeter.

The absolute unit of current flowing through a centimeter of wire acts with a force of 1 dyne on a unit of magnetism 1 centimeter distant from every point of the wire.

An ampere, the practical unit of current, is the electromotive force of 1 volt against a resistance of 1 ohm. It is the tenth part of the absolute unit. An ordinary dry cell gives a current of about 2 amperes, a Daniels wet cell, 1 ampere. Dry cells differ somewhat in strength.

A volt, conversely, is the electromotive force, or “electric pressure,” which, flowing in a conductor having a resistance of 1 ohm, will yield 1 ampere of current. The ordinary dry cell, when fresh, has an electromotive force of about 2 volts.

The ohm is the unit of resistance. For all practical purposes it is the resistance of 50 meters of copper wire 1 millimeter in diameter. Theoretically it was intended to be the resistance of a wire in which 1 ampere of current in 1 second would generate the amount of heat equivalent to 10,000,000 ergs.

The watt is the unit of power. At the rate of 10,000,000 ergs per second, a current of 1 ampere having the pressure of 1 volt has a value of 1 watt. A common candle has the heating equivalent of about 60 watts. One horse power, the power required to lift 33,000 pounds 1 foot high in a minute of time, is rated about 746 watts.

A coulomb is the unit of quantity. It is the quantity of electricity transferred by a current of 1 ampere in one second.

The farad is the unit of capacity. The capacity of a condenser is theoretically the electricity that can be stored in it by a cell of known electromotive force. For purposes of exact measurement the cell should have an electromotive force equal to 1 unit absolute measure. It is practically a condenser which, charged with 1 coulomb of current, has a difference of potential of 1 volt.

Chemical Formulas

Freezing Mixtures.—Salt, 1 part; snow at 32°, 2 parts, produce a zero mixture.

Calcium chloride, 2 parts; snow at 32°, 1 part, produce a temperature of −40° F.

Potassium hydrate (concentrated) at 32° and snow at 32°, equal parts, produce a temperature of −30° F.

Ammonium chloride, potassium nitrate and water at 32°, equal parts, produce a temperature of −10° F.

The temperature produced by these mixtures is approximate only. The first mentioned may vary not more than 3 degrees; usually the variation is not more than 1 degree; a variation of as much as 10 degrees may occur in the second. As a rule, the larger the volume of the mixture the better the result.

Chemical Hygroscopes.—Various chemical salts are sensitive to the moisture of the air; some of them change color with the absorption or the discharge of moisture. Cobaltic chloride is the basis of most of the commercial hygroscopes of this character. A solution consisting of 5 grains of cobaltic chloride, 50 grains of gelatine and 1 fluid ounce of water is a good porportion. There must be a complete emulsification of the gelatine. A strip of unsized paper wet with the emulsion is normally pink in moist air, violet in moderately moist air, and blue in dry air. When the winter fires are on in dwellings, the strip of paper is persistently blue. Ordinarily it does not begin to turn until the moisture of the air is about 75 per cent.

Ozone Test Papers.—Qualitative tests for ozone are often desirable. The following solution is highly regarded. Distilled water, 1 oz; starch, 25 grains; potassium iodide, 4 grains. Dissolve the potassium iodide in a small part of the water; boil the starch in the remaining part; mix and shake thoroughly. Moisten strips of unsized white paper and suspend them in the thermometer shelter or in shaded open air. Usually an exposure of from 3 hours to 10 hours is required. The ozone decomposes the potassium iodide, thereby turning the paper blue in color. This is probably the best test.

A slip of paper moistened with a solution of manganous sulphate is turned brown by ozone. The reaction oxidizes the manganous to manganic sulphate.

A paper strip smeared thinly with lead sulphide is more or less bleached by ozone, the sulphide being oxidized to a sulphate, which is white. This test is characteristic if the sulphide is smeared upon black paper.

Storm Glasses. — The so-called “storm-glass” which is sold under several fanciful names, consists of a solution just beyond the point of precipitation inclosed in a thin glass tube about 7 inches long and half an inch in diameter. The solution consists of camphor, 10 parts; potassium nitrate (saltpeter) 5 parts; ammonium chloride (sal ammoniac) 5 parts; 95 per cent alcohol 105 parts; and distilled water 45 parts. The virtue of the solution depends on the fact that neither the solution nor the precipitation is complete; the proportion of alcohol must be regulated to prevent more than a small part of the chemical salts from precipitation. The glass must be thin enough and elastic enough to yield slightly to changes in atmospheric pressure. About 1 inch of air space in the tube adds to the sensitiveness of precipitation. An increase in pressure causes the precipitation to extend nearly to the top of the solution; a decrease causes increased solution and a settling to the bottom of the tube. With a very low barometer the precipitated matter sinks to the bottom and becomes gelatinous. Increase of pressure is followed by the formation of minute crystals that grow in size. The only weather changes indicated are those foretold by a rising or by a falling barometer.

Table 1—Miscellaneous Equivalents

Linear Equivalents

1 mile	=320 rods
	=1760 yards
	=5280 ft
	=63360 in
	=1.60935 kilometers

1 rod	=0.003125 mi
	=16.5 ft.
	=198.0 in
	=5.0292 meters

1 yard	=0.000568 mi
	=0.9144 meter

1 foot	=0.3333 yd
	=0.000189 mi
	=0.3048 meter

1 inch	=1000 mils
	=0.08333 ft
	=0.02777 yd
	=2.54 centimeters

1 mil	=0.001 in
	=0.0254 millimeter

1 fathom	=6 ft
	=1.8288 meter

1 nautical mile	=6080.27 ft US
	=1.1516 stat mi US
	=6080 ft Br Ad
	=1.1515 stat mi
1 statute mile	=0.8684 naut mi US
1 geographical mile	=0°1′ at equator
	=6087.15 ft
	=1.1528 stat mi

1 nautical mi Br Ad
1 nautical mi Br	=1853.248 meters
1 geographical mi (U S)
	=1855.345 meters

1 chain (engineers)
1 chain (engin	=100 ft
	=6.0606 rods
	=1.5157 Gunter’s chain
	=30.48 meters

1 Gunter’s chain	=66 ft
	=4 rods
	=0.66 chain
	=0.0125 mi
	=20.1168 meters

1 link

=7. 92 in

1 kilometer	=0.62137 mi
	=198.8384 rods
	=1093.61 yds
	=3280.83 ft

1 meter	=39.37 in
	=3.28083 ft
	=1.09361 yds

1 centimeter	=0.3937 in
	=0.032808 ft

1 millimeter	=0.03937 m

	=39.37 mils
	=1000 mikrons

1 mikron

=0.001 mm

Square Equivalents

1 square mile	=640 acres
	=102400 sq rd
	=3,097,600 sq yd
	=27,878,400 sq ft
	=2.59 sq kilo

1 acre	=160 sq rd
	=4840 sq yd
	=43560 sq ft
	=4046.87 sq meters
	=0.0404687 hectare

1 square yd	=0.83613 sq meter
1 square foot	=0.1111 sq yd
	=144 sq in
	=0.0929 sq meter
	= 929.03 sq cm

1 square inch	=0.006944 sq ft
	=6.4516 sq cm

1 square mil	=0.00001 sq in
	=0.00064516 sq mm

1 square kilometer
1 square foot	=0.3861 sq mi
	=247.105 acres
	=1,000,000 sq meters

1 square meter	=1.196 sq yd
	=10.7639 sq ft
	=1550 sq in

1 square centimeter
1 square foot	=0.155 sq in
	=0.0001 sq meter

1 square millimeter	=1550 sq mils
	=0.00155 sq m

1 hectare	=2.471 acres
	=107,639 sq ft

Cubic Equivalents

1 cubic yard	=27 cu ft = 46,656
1 cu in	=0.76456 cu meter

1 cubic foot	=0.037 cu yd
	= 1728 cu in
	=7.4805 U S gals
	=6.2321 Imp gal
	=0.0283 cu meter
	=28317 cu cm

1 cubic inch

=16. 3872 cu cm

1 cubic meter	=1.30794 cu yd
	=35.3145 cu ft
	=61,023.4 cu in

1 cubic decimeter (1 liter)
1 cubic decimeter	=0.03531 cu ft
	61 .0234 cu in
	=1000 cu cm
	=0.26417 U S gal
	=0.22 Imp gal

Capacity

1 bushel U S
	=1.24445 cu ft
	=2150.4 cu in

1 bushel Br

=1.28368

1 gallon U S	=0.133681 cu ft

	=231 cu in
	=3.78543 liters
	=3785 cu cm
	=4 qts
	=8 pts

A cylinder 7 in diameter and 6 in high has a capacity of 230.9 cu in—practically 1 gal.

1 gallon, Imperial	=277.274 cu in
	=4.5437 liters

1 quart	=57.75 cu in
	=946.25 cu cm

1 fluid ounce	=1.8047 cu in
	=29.574 cu cm

Weight

1 ton, long	=2240 lbs (av)
	=1.016 met tons
	=1016.05 kg

1 ton, short	=2000 lbs
	=0.907 met ton
	=907 kilo

1 pound avoirdupois	= 16 oz
	=7000 grains
	=0.4536 kg
	=453-59 gram

1 pound troy	=12 oz
	=5760 grains
	=372.631 grams
	=0.373 2 3 kg

1 ounce avoirdupois	=437.5 grains
	=0.0625 lb
	=28.35 grams

1 ounce troy	=480 grains
	=0.0833 lb
	=31.1 grams

1 metric ton	=0.9842 long tons
	=1.1023 short tons
	=2204.62 lbs
	=1000 kg

1 kilogram	=2.20462 lb av
	=2.6792 lb troy
	=35.274 oz av
	=33.140 oz troy

1 gram	=15.432 grains
	= 1000 mg
	=1 cu cm water
1 grain	=0.0648 gram

Work Equivalents

1 horse power
1 horse po	=33,000 ft lb per min
	=1,980,000 ft lb per sec
	=273,746 kg meters
	=2,685,443 joules
	=2544.99 lb
	=641.326 kilo

1 Br. therm, unit	=1 lb 1° F
	=778 ft lb
	=0.252 kg C°
	=107.56 kg meters

1 joule	=0.7373 ft lb
	=0.102 kg meter

1 kilogrammeter
1 kilogrammete	=7.89 h p min
	=0.1315 h p sec
	=7233 ft lb
	=0.8 met h p min
	=0.0133 rnet h p sec
	=9.81 joules

1 kilogram degree C°
1 kilogram degree	= 3087.35 ft lb
	=3.968 deg lb F°
	=426.84 kg meters

1 metric horse power
1 metric horse	=1,952,910 ft lb (hour)
	=2,648,700 joules

Precipitation

1 acre foot	=43, 500 cu ft
	=325,850.58 US gal
	=0.6234 U S gal per sq ft
	=1233.46 cu meters
	=1344.2 tons

1 acre inch	=3630 cu ft
	=27154.21 U S gal
	=102.8 cu meters
	=112.01 tons

1 acre centimeter
1 acre ce	=0.24542 U S gal per sq ft

Atmospheric Equivalents

t = 32°

P = 29.92 in or 760 mm

1 cubic yard of air	=2.17888 lb av
	=988.615 grams

1 cubic foot of air	=0.807 lb av
	=565.061 grains
	=36.615 grams
	=1.291 oz av

1 atmosphere	=29.921 in of mercury
	=760 mm of mercury
	=33.9 ft of water
	=14.7 lb per sq in
	=1.0333 kg per sq cm

1 metric atmosphere
1 metric atmosp	=0.9678 atmosphere

1 cubic meter of air (32° F)
1 cubic meter of air (32°	=2.85 lb
	=1 . 293 kg

Velocity

1 inch per second
1 inch per seco	=300 ft per hour
	=152.4 cm per min

1 foot per second
1 foot per seco	=60 ft per min
	=3600 ft per hour
	=0.682 mi per hour
	=1.097 kilo per hour

1 mile per hour
1 mile per ho	=1.466 ft per sec
	=88 ft per min
	=0.447 meter per sec
	=26.822 meters per min

1 mile per min
1 mile per m	=5280 ft per min
	=96.5608 kilo per hour
	=16.035 kilo per min

1 kilometer per min
1 kilometer pe	=2.2369 mi per hour
	=96.5608 ft per min

Miscellaneous

1 knot

1 k =rate of 1 nautical mile per hour

1′ of longitude at equator
1′ of longitude at e	=1855.345 meters
	=6087.15 ft

1′ of latitude at equator
1′ of latitude at eq	=1842.787 meters
	=6045.95 ft
	=1.14507 st mi

1′ longitude at equator
1′ of longitude at equ	=1.15287 st mi

Equatorial radius of earth
Equatorial radius	=3962.571 mi

Polar radius of earth
Polar radius of ear	=3949.67 mi

1 cu ft of ice at 32°

=57.5 lbs

1 lb of ice at 32°

=0.0174 cu ft

1 inch of mercury in the barometer
1 inch of	tube=13.5956 in of water

Table 2—Inches to Centimeters
Inches	0	1 in	2 in	3 in	4 in	5 in	6 in	7 in	8 in	9 in
	cm	cm	cm	cm	cm	cm	cm	cm	cm	cm
0		2.54	5.08	7.62	10.16	12.70	15.24	17.78	20.32	22.86
10	25.40	27.94	30.48	33.02	35.56	38.10	40.64	43.18	45.72	48.26
20	50.80	53.34	55.88	58.42	60.96	63.50	66.04	68.58	71.12	73.66
30	76.20	78.74	81.28	83.82	86.36	88.90	91.44	93.98	96.52	99.06
40	101.60	104.14	106.68	109.22	111.76	114.30	116.84	119.38	121.92	124.46
50	127.00	129.54	132.08	134.62	137.16	139.70	142.24	144.78	147.32	149.86
60	152.40	154.94	157.48	160.02	162.56	165.10	167.64	170.18	172.72	175.26
70	177.80	180.34	182.88	185.42	187.96	190.50	193.04	195.58	198.12	200.66
80	203.20	205.74	208.28	210.82	213.36	215.90	218.44	220.98	223.52	226.06
90	228.60	231.14	233.68	236.22	238.76	241.30	243.84	246.38	248.92	251.46
100	254.00	256.54	259.08	261.62	264.16	266.70	269.24	271.78	274.32	276.86

Table 3—Centimeters to Inches
Centi- meters	0	1 cm	2 cm	3 cm	4 cm	5 cm	6 cm	7 cm	8 cm	9 cm
	in	in	in	in	in	in	in	in	in	in
0		0.394	0.788	1.182	1.576	1.970	2.364	2.758	3.152	3.546
10	3.940	4.334	4.728	5.122	5.516	5.910	6.304	6.698	7.092	7.486
20	7.880	8.274	8.668	9.062	9.456	9.850	10.244	10.638	11.032	11.426
30	11.820	12.214	12.608	13.002	13.396	13.790	14.184	14.578	14.972	15.366
40	15.760	16.154	16.548	16.942	17.336	17.730	18.124	18.518	18.912	19.306
50	19.700	20.094	20.488	20.882	21.276	21.670	22.064	22.458	22.852	23.246
60	23.640	24.034	24.428	24.822	25.216	25.610	26.004	26.398	26.792	27.186
70	27.580	27.974	28.368	28.762	29.156	29.550	29.944	30.338	30.732	31.126
80	31.520	31.914	32.308	32.702	33.096	33.490	33.884	34.278	34.672	35.066
90	35.460	35.854	36.248	36.642	37.036	37.430	37.824	38.218	38.612	39.006
100	39.400	39.794	40.188	40.582	40.976	41.370	41.764	42.158	42.552	42.946

1 inch= 2.540005 centimeters; 1 centimeter = 0.397 inch.

Table 4—Cubic inches to Cubic centimeters
	0	1	2	3	4	5	6	7	8	9
0		16.39	32.77	49.16	65.55	81.94	98.32	114.71	131.10	147.48
10	163.87	180.26	196.65	213.03	229.42	245.81	262.19	278.58	294.97	311.35
20	327.74	344.13	360.52	376.90	393.29	409.68	426.06	442.45	458.84	475.23
30	491.61	508.00	524.39	540.77	557.16	573.55	589.94	606.32	622.71	639.10
40	655.48	671.87	688.26	704.65	721.03	737.42	753.81	770.19	786.58	802.97
50	819.36	835.74	852.13	868.52	884.90	901.29	917.68	934.06	950.45	966.84
60	983.23	999.61	1016.0	1032.4	1048.8	1065.2	1081.5	1097.9	1114.3	1130.7
70	1147.1	1163.5	1179.9	1196.3	1212.6	1229.0	1245.4	1261.8	1278.2	1294.6
80	1311.0	1327.4	1343.7	1360.1	1376.5	1392.9	1409.3	1425.7	1442.1	1458.5
90	1474.8	1491.2	1507.6	1524.0	1540.4	1556.8	1573.2	1589.5	1605.9	1622.3
100	1638.7	1655.1	1671.5	1687.9	1704.3	1720.6	1737.0	1753.4	1769.8	1786.2

Table 5—Cubic centimeters to Cubic inches
	0	1	2	3	4	5	6	7	8	9
0		0.0610	0.1220	0.1831	0.2441	0.3051	0.3661	0.4272	0.4882	0.5492
10	0.6102	0.6713	0.7323	0.7933	0.8543	0.9154	0.9764	1.0374	1.0984	1.1595
20	1.2205	1.2815	1.3425	1.4035	1.4646	1.5256	1.5866	1.6476	1.7087	1.7697
30	1.8307	1.8917	1.9528	2.0138	2.0748	2.1358	2.1969	2.2579	2.3189	2.3799
40	2.4409	2.5020	2.5630	2.6240	2.6850	2.7461	2.8071	2.8681	2.9291	2.9902
50	3.0512	3.1122	3.1732	3.2343	3.2953	3.3563	3.4173	3.4784	3.5394	3.6004
60	3.6614	3.7224	3.7835	3.8445	3.9055	3.9665	4.0276	4.0886	4.1496	4.2106
70	4.2717	4.3327	4.3937	4.4547	4.5158	4.5768	4.6378	4.6988	4.7598	4.8209
80	4.8819	4.9429	5.0039	5.0650	5.1260	5.1870	5.2480	5.3091	5.3701	5.4311
90	5.4921	5.5532	5.6142	5.6752	5.7362	5.7973	5.8583	5.9193	5.9803	6.0413
100	6.1024	6.1634	6.2244	6.2854	6.3465	6.4075	6.4685	6.5295	6.5906	6.6516

1 cubic inch = 16.3872 cubic centimeters; 1 cubic centimeter 0.061023 cubic inch.

Table 6—Miles to Kilometers
Miles	0	1	2	3	4	5	6	7	8	9
	kilom	kilom	kilom	kilom	kilom	kilom	kilom	kilom	kilom	kilom
0		1.609	3.219	4.828	6.437	8.047	9.656	11.265	12.875	14.484
10	16.093	17.703	19.312	20.921	22.531	24.140	25.750	27.359	28.968	30.578
20	32.187	33.796	35.406	37.015	38.624	40.234	41.843	43.452	45.062	46.671
30	48.280	49.890	51.499	53.108	54.718	56.327	57.936	59.546	61.155	62.764
40	64.374	65.983	67.592	69.202	70.811	72.420	74.030	75.639	77.249	78.858
50	80.467	82.077	83.686	85.295	86.905	88.514	90.123	91.733	93.342	94.951
60	96.561	98.170	99.779	101.39	103.00	104.61	106.22	107.83	109.44	111.04
70	112.65	114.26	115.87	117.48	119.09	120.70	122.31	123.92	125.53	127.14
80	128.75	130.36	131.97	133.58	135.18	136.79	138.40	140.01	141.62	143.23
90	144.84	146.45	148.06	149.67	151.28	152.89	154.50	156.11	157.72	159.33
100	160.93	162.54	164.15	165.76	167.37	168.98	170.59	172.20	173.81	175.42

Table 7—Kilometers to Miles
Kilom	0	1	2	3	4	5	6	7	8	9
	mi	mi	mi	mi	mi	mi	mi	mi	mi	mi
0		0.6214	1.2427	1.8641	2.4855	3.1069	3.7282	4.3496	4.9710	5.5923
10	6.2137	6.8351	7.4565	8.0778	8.6992	9.3206	9.9419	10.563	11.185	11.806
20	12.427	13.049	13.670	14.292	14.913	15.534	16.156	16.777	17.398	18.020
30	18.641	19.263	19.884	20.505	21.127	21.748	22.369	22.991	23.612	24.233
40	24.855	25.476	26.098	26.719	27.340	27.962	28.583	29.204	29.826	30.447
50	31.069	31.690	32.311	32.933	33.554	34.175	34.797	35.418	36.040	36.661
60	37.282	37.904	38.525	39.146	39.768	40.389	41.010	41.632	42.253	42.875
70	43.496	44.117	44.739	45.360	45.981	46.603	47.224	47.846	48.467	49.088
80	49.710	50.331	50.952	51.574	52.195	52.817	53.438	54.059	54.681	55.302
90	55.923	56.545	57.166	57.788	58.409	59.030	59.652	60.273	60.894	61.516
100	62.137	62.758	63.380	64.001	64.623	65.244	65.865	66.487	67.108	67.729

1 mi. = 1.609347 kilometers; 1 kilometer = 0.62137 mile.

Table 8—Feet to Meters
	0	1	2	3	4	5	6	7	8	9
0		0.305	0.610	0.914	1.219	1.524	1.829	2.134	2.438	2.743
10	3.048	3.353	3.658	3.962	4.267	4.572	4.877	5.182	5.486	5.791
20	6.096	6.401	6.706	7.010	7.315	7.620	7.925	8.230	8.534	8.839
30	9.144	9.449	9.754	10.058	10.363	10.668	10.973	11.278	11.582	11.887
40	12.192	12.497	12.802	13.106	13.411	13.716	14.021	14.326	14.630	14.935
50	15.240	15.545	15.850	16.154	16.459	16.764	17.069	17.374	17.678	17.983
60	18.288	18.593	18.898	19.202	19.507	19.812	20.117	20.422	20.726	21.031
70	21.336	21.641	21.946	22.250	22.555	22.860	23.165	23.470	23.774	24.079
80	24.384	24.689	24.994	25.298	25.603	25.908	26.213	26.518	26.822	27.127
90	27.432	27.737	28.042	28.346	28.651	28.956	29.261	29.566	29.870	30.175
100	30.480	30.785	————	————	————	————	————	————	————	————

Table 9—Meters to Feet
	0	1	2	3	4	5	6	7	8	9
0		3.281	6.562	9.842	13.123	16.404	19.685	22.966	26.247	29.527
10	32.808	36.089	39.370	42.651	45.932	49.212	52.493	55.774	59.055	62.336
20	65.617	68.897	72.178	75.459	78.740	82.021	85.302	88.582	91.863	95.144
30	98.425	101.71	104.99	108.27	111.55	114.83	118.11	121.39	124.67	127.95
40	131.23	134.51	137.79	141.08	144.36	147.64	150.92	154.20	157.48	160.76
50	164.04	167.32	170.60	173.88	177.16	180.45	183.73	187.01	190.29	193.57
60	196.85	200.13	203.41	206.69	209.97	213.25	216.53	219.82	223.10	226.38
70	229.66	232.94	236.22	239.50	242.78	246.06	249.34	252.62	255.90	259.19
80	262.47	265.75	269.03	272.31	275.59	278.87	282.15	285.43	288.71	291.99
90	295.27	298.56	301.84	305.12	308.40	311.68	314.96	318.24	321.52	324.80
100	328.08	————	————	————	————	————	————	————	————	————

1 foot = 0.3048006 meter; 1 meter = 3.280833 feet.

Table 10—Barometer Inches to Millimeters
Inches	.0	.01	.02	.03	.04	.05	.06	.07	.08	.09
	mm	mm	mm	mm	mm	mm	mm	mm	mm	mm
0.0	0.00	2.54	5.08	7.62	10.16	12.70	15.24	17.78	20.32	22.86
0.1	0.25	2.79	5.33	7.87	10.41	12.95	15.49	18.03	20.57	23.11
0.2	0.51	3.05	5.59	8.13	10.67	13.21	15.75	18.29	20.83	23.37
0.3	0.76	3.30	5.84	8.38	10.92	13.46	16.00	18.54	21.08	23.62
0.4	1.02	3.56	6.10	8.64	11.18	13.72	16.26	18.80	21.34	23.88
0.5	1.27	3.81	6.35	8.89	11.43	13.97	16.51	19.05	21.59	24.13
0.6	1.52	4.06	6.60	9.14	11.68	14.22	16.76	19.30	21.84	24.38
0.7	1.78	4.32	6.86	9.40	11.94	14.48	17.02	19.56	22.10	24.64
0.8	2.03	4.57	7.11	9.65	12.19	14.73	17.27	19.81	22.35	24.89
0.9	2.29	4.83	7.37	9.91	12.45	14.99	17.53	20.07	22.61	25.15

Proportional Parts


in	in	in	in	in	in	in	in	in	in	in	in
1.00	2.00	3.00	4.00	5.00	6.00	7.00	8.00	9.00	10.00	20.00	30.00
mm	mm	mm	mm	mm	mm	mm	mm	mm	mm	mm	mm
25.40	50.80	76.20	101.60	127.00	152.40	177.80	203.20	228.60	254.00	508.00	762.00


in	in	in	in	in	in	in	in	in	in
0.001	0.002	0.003	0.004	0.005	0.006	0.007	0.008	0.009	0.010
mm	mm	mm	mm	mm	mm	mm	mm	mm	mm
0.025	0.051	0.076	0.102	0.127	0.152	0.178	0.203	0.229	0.254

Table 11—Barometer Millimeters to Inches
Milli- meters	0	1	2	3	4	5	6	7	8	9
	in	in	in	in	in	in	in	in	in	in
0	0.0000	0.0394	0.0787	0.1181	0.1575	0.1969	0.2362	0.2756	0.3150	0.3543
10	0.3937	0.4331	0.4724	0.5118	0.5512	0.5906	0.6299	0.6693	0.7087	0.7480
20	0.7874	0.8268	0.8661	0.9055	0.9449	0.9843	1.0236	1.0630	1.1024	1.1417
30	1.1811	1.2205	1.2598	1.2992	1.3386	1.3780	1.4173	1.4567	1.4961	1.5354
40	1.5748	1.6142	1.6535	1.6929	1.7323	1.7717	1.8110	1.8504	1.8898	1.9291
50	1.9685	2.0079	2.0472	2.0866	2.1260	2.1654	2.2047	2.2441	2.2835	2.3228
60	2.3622	2.4016	2.4409	2.4803	2.5197	2.5591	2.5984	2.6378	2.6772	2.7165
70	2.7559	2.7953	2.8346	2.8740	2.9134	2.9528	2.9921	3.0315	3.0709	3.1102
80	3.1496	3.1890	3.2283	3.2677	3.3071	3.3465	3.3858	3.4252	3.4646	3.5039
90	3.5433	3.5827	3.6220	3.6614	3.7008	3.7402	3.7795	3.8189	3.8583	3.8976

Proportionate Parts

mm	mm	mm	mm	mm	mm	mm	mm
100	200	300	400	500	600	700	800
in	in	in	in	in	in	in	in
3.937	7.874	11.811	15.748	19.685	23.622	27.559	31.496

mm	mm	mm	mm	mm	mm	mm	mm	mm	mm
0.1	0.2	0.3	0.4	0.5	0.6	0.7	0.8	0.9	1.0
in	in	in	in	in	in	in	in	in	in
0.0039	0.0079	0.0118	0.0157	0.0197	0.0236	0.0276	0.0315	0.0354	0.0394

mm	mm	mm	mm	mm	mm	mm	mm	mm	mm
0.01	0.02	0.03	0.04	0.05	0.06	0.07	0.08	0.09	0.1
in	in	in	in	in	in	in	in	in	in
0.0004	0.0008	0.0012	0.0016	0.0020	0.0024	0.0028	0.0031	0.0035	0.0039

Table 12—Barometer Inches to Kilobars
31.00	1049.8	30.80	1043.1	30.60	1036.3	30.40	1029.5	30.20	1022.8	30.00	1016.0	29.80	1009.2
30.99	1049.5	30.79	1042.7	30.59	1036.0	30.39	1029.2	30.19	1022.4	29.99	1015.6	29.79	1008.9
30.98	1049.2	30.78	1042.4	30.58	1035.6	30.38	1028.8	30.18	1022.1	29.98	1015.3	29.78	1008.5
30.97	1048.8	30.77	1042.1	30.57	1035.3	30.37	1028.5	30.17	1021.7	29.97	1015.0	29.77	1008.2
30.96	1048.5	30.76	1041.7	30.56	1034.9	30.36	1028.2	30.16	1021.4	29.96	1014.6	29.76	1007.9
30.95	1048.2	30.75	1041.4	30.55	1034.6	30.35	1027.8	30.15	1021.1	29.95	1014.3	29.75	1007.5
30.94	1047.8	30.74	1041.0	30.54	1034.3	30.34	1027.5	30.14	1020.7	29.94	1013.9	29.74	1007.2
30.93	1047.5	30.73	1040.7	30.53	1033.9	30.33	1027.2	30.13	1020.4	29.93	1013.6	29.73	1006.8
30.92	1047.1	30.72	1040.4	30.52	1033.6	30.32	1026.8	30.12	1020.0	29.92	1013.3	29.72	1006.5
30.91	1046.8	30.71	1040.0	30.51	1033.3	30.31	1026.5	30.11	1019.7	29.91	1012.9	29.71	1006.2
30.90	1046.5	30.70	1039.7	30.50	1032.9	30.30	1026.1	30.10	1019.4	29.90	1012.6	29.70	1005.8
30.89	1046.1	30.69	1039.3	30.49	1032.6	30.29	1025.8	30.09	1019.0	29.89	1012.3	29.69	1005.5
30.88	1045.8	30.68	1039.0	30.48	1032.2	30.28	1025.5	30.08	1018.7	29.88	1011.9	29.68	1005.1
30.87	1045.4	30.67	1038.7	30.47	1031.9	30.27	1025.1	30.07	1018.4	29.87	1011.6	29.67	1004.8
30.86	1045.1	30.66	1038.3	30.46	1031.6	30.26	1024.8	30.06	1018.0	29.86	1011.2	29.66	1004.5
30.85	1044.8	30.65	1038.0	30.45	1031.2	30.25	1024.4	30.05	1017.7	29.85	1010.9	29.65	1004.1
30.84	1044.4	30.64	1037.7	30.44	1030.9	30.24	1024.1	30.04	1017.3	29.84	1010.6	29.64	1003.8
30.83	1044.1	30.63	1037.3	30.43	1030.5	30.23	1023.8	30.03	1017.0	29.83	1010.2	29.63	1003.4
30.82	1043.8	30.62	1037.0	30.42	1030.2	30.22	1023.4	30.02	1016.7	29.82	1009.9	29.62	1003.1
30.81	1043.4	30.61	1036.6	30.41	1029.9	30.21	1023.1	30.01	1016.3	29.81	1009.5	29.61	1002.8

Table 12—Barometer Inches to Kilobars—*Continued*
29.59	1002.1	29.39	995.3	29.19	988.5	28.99	981.8	28.79	975.0	28.59	968.2
29.58	1001.8	29.38	995.0	29.18	988.2	28.98	981.4	28.78	974.7	28.58	967.9
29.57	1001.4	29.37	994.6	29.17	987.9	28.97	981.1	28.77	974.3	28.57	967.6
29.56	1001.1	29.36	994.3	29.16	987.5	28.96	980.8	28.76	974.0	28.56	967.2
29.55	1000.7	29.35	994.0	29.15	987.2	28.95	980.4	28.75	973.6	28.55	966.9
29.54	1000.4	29.34	993.6	29.14	986.9	28.94	980.1	28.74	973.3	28.54	966.5
29.53	1000.1	29.33	993.3	29.13	986.5	28.93	979.7	28.73	973.0	28.53	966.2
29.52	999.7	29.32	993.0	29.12	986.2	28.92	979.4	28.72	972.6	28.52	965.9
29.51	999.4	29.31	992.6	29.11	985.8	28.91	979.1	28.71	972.3	28.51	965.5
29.50	999.0	29.30	992.3	29.10	985.5	28.90	978.7	28.70	972.0	28.50	965.2
29.49	998.7	29.29	991.9	29.09	985.2	28.89	978.4	28.69	971.6	28.49	964.8
29.48	998.4	29.28	991.6	29.08	984.8	28.88	978.1	28.68	971.3	28.48	964.5
29.47	998.0	29.27	991.3	29.07	984.5	28.87	977.7	28.67	970.9	28.47	964.2
29.46	997.7	29.26	990.9	29.06	984.1	28.86	977.4	28.66	970.6	28.46	963.8
29.45	997.4	29.25	990.6	29.05	983.8	28.85	977.0	28.65	970.3	28.45	963.5
29.44	997.0	29.24	990.2	29.04	983.5	28.84	976.7	28.64	969.9	28.44	963.1
29.43	996.7	29.23	989.9	29.03	983.1	28.83	976.4	28.63	969.6	28.43	962.8
29.42	996.3	29.22	989.6	29.02	982.8	28.82	976.0	28.62	969.2	28.42	962.5
29.41	996.0	29.21	989.2	29.01	982.5	28.81	975.7	28.61	968.9	28.41	962.1
29.40	995.7	29.20	988.9	29.00	982.1	28.80	975.3	28.60	968.6	28.40	961.8

Table 12—Barometer Inches to Kilobars—*Continued*
28.39	961.5	28.19	954.7	27.99	947.9	27.79	941.1	27.59	934.4	27.39	927.6
28.38	961.1	28.18	954.3	27.98	947.6	27.78	940.8	27.58	934.0	27.38	927.3
28.37	960.8	28.17	954.0	27.97	947.2	27.77	940.5	27.57	933.7	27.37	926.9
28.36	960.4	28.16	953.7	27.96	946.9	27.76	940.1	27.56	933.3	27.36	926.6
28.35	960.1	28.15	953.3	27.95	946.6	27.75	939.8	27.55	933.0	27.35	926.2
28.34	959.8	28.14	953.0	27.94	946.2	27.74	939.4	27.54	932.7	27.34	925.9
28.33	959.4	28.13	952.7	27.93	945.9	27.73	939.1	27.53	932.3	27.33	925.6
28.32	959.1	28.12	952.3	27.92	945.5	27.72	938.8	27.52	932.0	27.32	925.2
28.31	958.7	28.11	952.0	27.91	945.2	27.71	938.4	27.51	931.7	27.31	924.9
28.30	958.4	28.10	951.6	27.90	944.9	27.70	938.1	27.50	931.3	27.30	924.5
28.29	958.1	28.09	951.3	27.89	944.5	27.69	937.7	27.49	931.0	27.29	924.2
28.28	957.7	28.08	951.0	27.88	944.2	27.68	937.4	27.48	930.6	27.28	923.9
28.27	957.4	28.07	950.6	27.87	943.8	27.67	937.1	27.47	930.3	27.27	923.5
28.26	957.1	28.06	950.3	27.86	943.5	27.66	936.7	27.46	930.0	27.26	923.2
28.25	956.7	28.05	949.9	27.85	943.2	27.65	936.4	27.45	929.6	27.25	922.8
28.24	956.4	28.04	949.6	27.84	942.8	27.64	936.1	27.44	929.3	27.24	922.5
28.23	956.0	28.03	949.3	27.83	942.5	27.63	935.7	27.43	928.9	27.23	922.2
28.22	955.7	28.02	948.9	27.82	942.2	27.62	935.4	27.42	928.6	27.22	921.8
28.21	955.4	28.01	948.6	27.81	941.8	27.61	935.0	27.41	928.3	27.21	921.5
28.20	955.0	28.00	948.2	27.80	941.5	27.60	934.7	27.40	927.9	27.20	921.2

Table 12—Barometer Inches to Kilobars—*Continued*
27.19	920.8	26.99	914.0	26.79	907.3	26.59	900.5	26.39	893.7	26.19	887.0
27.18	920.5	26.98	913.7	26.78	906.9	26.58	900.2	26.38	893.4	26.18	886.6
27.17	920.1	26.97	913.4	26.77	906.6	26.57	899.8	26.37	893.0	26.17	886.3
27.16	919.8	26.96	913.0	26.76	906.3	26.56	899.5	26.36	892.7	26.16	885.9
27.15	919.5	26.95	912.7	26.75	905.9	26.55	899.1	26.35	892.4	26.15	885.6
27.14	919.1	26.94	912.4	26.74	905.6	26.54	898.8	26.34	892.0	26.14	885.3
27.13	918.8	26.93	912.0	26.73	905.2	26.53	898.5	26.33	891.7	26.13	884.9
27.12	918.4	26.92	911.7	26.72	904.9	26.52	898.1	26.32	891.4	26.12	884.6
27.11	918.1	26.91	911.3	26.71	904.6	26.51	897.8	26.31	891.0	26.11	884.2
27.10	917.8	26.90	911.0	26.70	904.2	26.50	897.4	26.30	890.7	26.10	883.9
27.09	917.4	26.89	910.7	26.69	903.9	26.49	897.1	26.29	890.3	26.09	883.6
27.08	917.1	26.88	910.3	26.68	903.5	26.48	896.8	26.28	890.0	26.08	883.2
27.07	916.8	26.87	910.0	26.67	903.2	26.47	896.4	26.27	889.7	26.07	882.9
27.06	916.4	26.86	909.6	26.66	902.9	26.46	896.1	26.26	889.3	26.06	882.5
27.05	916.1	26.85	909.3	26.65	902.5	26.45	895.8	26.25	889.0	26.05	882.2
27.04	915.7	26.84	909.0	26.64	902.2	26.44	895.4	26.24	888.6	26.04	881.9
27.03	915.4	26.83	908.6	26.63	901.9	26.43	895.1	26.23	888.3	26.03	881.5
27.02	915.1	26.82	908.3	26.62	901.5	26.42	894.7	26.22	888.0	26.02	881.2
27.01	914.7	26.81	907.9	26.61	901.2	26.41	894.4	26.21	887.6	26.01	880.9
27.00	914.4	26.80	907.6	26.60	900.8	26.40	894.1	26.20	887.3	26.00	880.5

For the extension of this table multiply the number of inches and hundreths by 33.866, the value of 1 inch in kilobars
1 millimeter = 1.3332 kilobars. 1000 kilobars = 29.5306 barometer inches, or 750.076 millimeters.

Table 13—Miles per Hour to Feet per Second
Miles per hour	0	1	2	3	4	5	6	7	8	9
	meters per sec	meters per sec	meters per sec	meters per sec	meters per sec	meters per sec	meters per sec	meters per sec	meters per sec	meters per sec
0	0.00	0.45	0.89	1.34	1.79	2.24	2.68	3.13	3.58	4.02
10	4.47	4.92	5.36	5.81	6.26	6.71	7.15	7.60	8.05	8.49
20	8.94	9.39	9.83	10.28	10.73	11.18	11.62	12.07	12.52	12.96
30	13.41	13.86	14.31	14.75	15.20	15.65	16.09	16.54	16.99	17.43
40	17.88	18.33	18.78	19.22	19.67	20.12	20.56	21.01	21.46	21.91
50	22.35	22.80	23.25	23.69	24.14	24.59	25.03	25.48	25.93	26.38
60	26.82	27.27	27.72	28.16	28.61	29.06	29.50	29.95	30.40	30.85
70	31.29	31.74	32.19	32.63	33.08	33.53	33.98	34.42	34.87	35.32
80	35.76	36.21	36.66	37.10	37.55	38.00	38.45	38.89	39.34	39.79
90	40.23	40.68	41.13	41.57	42.02	42.47	42.92	43.36	43.81	44.26
100	44.70	45.15	45.60	46.05	46.49	46.94	47.39	47.83	48.28	48.73
110	49.17	49.62	50.07	50.52	50.96	51.41	51.86	52.30	52.75	53.20
120	53.64	54.09	54.54	54.99	55.43	55.88	56.33	56.77	57.22	57.67
130	58.12	58.56	59.01	59.46	59.90	60.35	60.80	61.24	61.69	62.14
140	62.59	63.03	63.48	63.93	64.37	64.82	65.27	65.72	66.16	66.61
150	67.06	67.50	67.95	68.40	68.84	69.29	69.74	70.19	70.63	71.08

1 mile per hour = 0.4470409 meters per second; 1 meter per second = 3.6 kilometers per hour; 1 kilometer per hour = ${\frac {10}{36}}$ meters per second.

1 mile per hour = ${\frac {44}{30}}$ foot per second; 1 foot per second = ${\frac {30}{44}}$ mile per hour.

Table 14—Meters per Second to Miles per Hour
Meters per sec	0.0	0.1	0.2	0.3	0.4	0.5	0.6	0.7	0.8	0.9
	miles per hour	miles per hour	miles per hour	miles per hour	miles per hour	miles per hour	miles per hour	miles per hour	miles per hour	miles per hour
0	0.0	0.2	0.4	0.7	0.9	1.1	1.3	1.6	1.8	2.0
1	2.2	2.5	2.7	2.9	3.1	3.4	3.6	3.8	4.0	4.3
2	4.5	4.7	4.9	5.1	5.4	5.6	5.8	6.0	6.3	6.5
3	6.7	6.9	7.2	7.4	7.6	7.8	8.1	8.3	8.5	8.7
4	8.9	9.2	9.4	9.6	9.8	10.1	10.3	10.5	10.7	11.0
5	11.2	11.4	11.6	11.9	12.1	12.3	12.5	12.8	13.0	13.2
6	13.4	13.6	13.9	14.1	14.3	14.5	14.8	15.0	15.2	15.4
7	15.7	15.9	16.1	16.3	16.6	16.8	17.0	17.2	17.4	17.7
8	17.9	18.1	18.3	18.6	18.8	19.0	19.2	19.5	19.7	19.9
9	20.1	20.4	20.6	20.8	21.0	21.3	21.5	21.7	21.9	22.1
10	22.4	22.6	22.8	23.0	23.3	23.5	23.7	23.9	24.2	24.4
20	44.7	45.0	45.2	45.4	45.6	45.9	46.1	46.3	46.5	46.8
30	67.1	67.3	67.6	67.8	68.0	68.2	68.5	68.7	68.9	69.1
40	89.5	89.7	89.9	90.1	90.4	90.6	90.8	91.0	91.3	91.5
50	111.8	112.1	112.3	112.5	112.7	113.0	113.2	113.4	113.6	113.9
60	134.2	134.4	134.7	134.9	135.1	135.3	135.6	135.8	136.0	136.2

1 meter per second = 2.236932 miles per hour.

Table 15—Comparison of Approximate Absolute, Centigrade, and Fahrenheit Thermometer Scales
Abs°	C°	F°	Abs°	C°	F°	Abs°	C°	F°	Abs°	C°	F°	Abs°	C°	F°
374	100	212.0	349	75	167.0	324	50	122.0	299	25	77.0	274	±0	32.0
373	99	210.2	348	74	165.2	323	49	120.2	298	24	75.2	273	-1	30.2
372	98	208.4	347	73	163.4	322	48	118.4	297	23	73.4	272	-2	28.4
371	97	206.6	346	72	161.6	321	47	116.6	296	22	71.6	271	-3	26.6
370	96	204.8	345	71	159.8	320	46	114.8	295	21	69.8	270	-4	24.8
369	95	203.0	344	70	158.0	319	45	113.0	294	20	68.0	269	-5	23.0
368	94	201.2	343	69	156.2	318	44	111.2	293	19	66.2	268	-6	21.2
367	93	199.4	342	68	154.4	317	43	109.4	292	18	64.4	267	-7	19.4
366	92	197.6	341	67	152.6	316	42	107.6	291	17	62.6	266	-8	17.6
365	91	195.8	340	66	150.8	315	41	105.8	290	16	60.8	265	-9	15.8
364	90	194.0	339	65	149.0	314	40	104.0	289	15	59.0	264	-10	14.0
363	89	192.2	338	64	147.2	313	39	102.2	288	14	57.2	263	-11	12.2
362	88	190.4	337	63	145.4	312	38	100.4	287	13	55.4	262	-12	10.4
361	87	188.6	336	62	143.6	311	37	98.6	286	12	53.6	261	-13	8.6
360	86	186.8	335	61	141.8	310	36	96.8	285	11	51.8	260	-14	6.8
359	85	185.0	334	60	140.0	309	35	95.0	284	10	50.0	259	-15	5.0
358	84	183.2	333	59	138.2	308	34	93.2	283	9	48.2	258	-16	3.2
357	83	181.4	332	58	136.4	307	33	91.4	282	8	46.4	257	-17	1.4
356	82	179.6	331	57	134.6	306	32	89.6	281	7	44.6	256	-18	-0.4
355	81	177.8	330	56	132.8	305	31	87.8	280	6	42.8	255	-19	-2.2
354	80	176.0	329	55	131.0	304	30	86.0	279	5	41.0	254	-20	-4.0
353	79	174.2	328	54	129.2	303	29	84.2	278	4	39.2	253	-21	-5.8
352	78	172.4	327	53	127.4	302	28	82.4	277	3	37.4	252	-22	-7.6
351	77	170.6	326	52	125.6	301	27	80.6	276	2	35.6	251	-23	-9.4
350	76	168.8	325	51	123.8	300	26	78.8	275	+1	33.8	250	-24	-11.2

Table 15—Comparison of Approximate Absolute, Centigrade, and Fahrenheit Thermometer Scales—*Continued*
Abs°	C°	F°	Abs°	C°	F°	Abs°	C°	F°	Abs°	C°	F°	Abs°	C°	F°
248	-26	-14.8	223	-51	-59.8	198	-76	-104.8	173	-101	-149.8	148	-126	-194.8
247	-27	-16.6	222	-52	-61.6	197	-77	-106.6	172	-102	-151.6	147	-127	-196.6
246	-28	-18.4	221	-53	-63.4	196	-78	-108.4	171	-103	-153.4	146	-128	-198.4
245	-29	-20.2	220	-54	-65.2	195	-79	-110.2	170	-104	-155.2	145	-129	-200.2
244	-30	-22.0	219	-55	-67.0	194	-80	-112.0	169	-105	-157.0	144	-130	-202.0
243	-31	-23.8	218	-56	-68.8	193	-81	-113.8	168	-106	-158.8	143	-131	-203.8
242	-32	-25.6	217	-57	-70.6	192	-82	-115.6	167	-107	-160.6	142	-132	-205.6
241	-33	-27.4	216	-58	-72.4	191	-83	-117.4	166	-108	-162.4	141	-133	-207.4
240	-34	-29.2	215	-59	-74.2	190	-84	-119.2	165	-109	-164.2	140	-134	-209.2
239	-35	-31.0	214	-60	-76.0	189	-85	-121.0	164	-110	-166.0	139	-135	-211.0
238	-36	-32.8	213	-61	-77.8	188	-86	-122.8	163	-111	-167.8	138	-136	-212.8
237	-37	-34.6	212	-62	-79.6	187	-87	-124.6	162	-112	-169.6	137	-137	-214.6
236	-38	-36.4	211	-63	-81.4	186	-88	-126.4	161	-113	-171.4	136	-138	-216.4
235	-39	-38.2	210	-64	-83.2	185	-89	-128.2	160	-114	-173.2	135	-139	-218.2
234	-40	-40.0	209	-65	-85.0	184	-90	-130.0	159	-115	-175.0	134	-140	-220.0
233	-41	-41.8	208	-66	-86.8	183	-91	-131.8	158	-116	-176.8	133	-141	-221.8
232	-42	-43.6	207	-67	-88.6	182	-92	-133.6	157	-117	-178.6	132	-142	-223.6
231	-43	-45.4	206	-68	-90.4	181	-93	-135.4	156	-118	-180.4	131	-143	-225.4
230	-44	-47.2	205	-69	-92.2	180	-94	-137.2	155	-119	-182.2	130	-144	-227.2
229	-45	-49.0	204	-70	-94.0	179	-95	-139.0	154	-120	-184.0	129	-145	-229.0
228	-46	-50.8	203	-71	-95.8	178	-96	-140.8	153	-121	-185.8	128	-146	-230.8
227	-47	-52.6	202	-72	-97.6	177	-97	-142.6	152	-122	-187.6	127	-147	-232.6
226	-48	-54.4	201	-73	-99.4	176	-98	-144.4	151	-123	-189.4	126	-148	-234.4
225	-49	-56.2	200	-74	-101.2	175	-99	-146.2	150	-124	-191.2	125	-149	-236.2

Table 15—Comparison of Approximate Absolute, Centigrade, and Fahrenheit Thermometer Scales—*Continued*
Abs°	C°	F°	Abs°	C°	F°	Abs°	C°	F°	Abs°	C°	F°	Abs°	C°	F°
123	-151	-239.8	98	-176	-284.8	73	-201	-329.8	48	-226	-374.8	23	-251	-419.8
122	-152	-241.6	97	-177	-286.6	72	-202	-331.6	47	-227	-376.6	22	-252	-421.6
121	-153	-243.4	96	-178	-288.4	71	-203	-333.4	46	-228	-378.4	21	-253	-423.4
120	-154	-245.2	95	-179	-290.2	70	-204	-335.2	45	-229	-380.2	20	-254	-425.2
119	-155	-247.0	94	-180	-292.0	69	-205	-337.0	44	-230	-382.0	19	-255	-427.0
118	-156	-248.8	93	-181	-293.8	68	-206	-338.8	43	-231	-383.8	18	-256	-428.8
117	-157	-250.6	92	-182	-295.6	67	-207	-340.6	42	-232	-385.6	17	-257	-430.6
116	-158	-252.4	91	-183	-297.4	66	-208	-342.4	41	-233	-387.4	16	-258	-432.4
115	-159	-254.2	90	-184	-299.2	65	-209	-344.2	40	-234	-389.2	15	-259	-434.2
114	-160	-256.0	89	-185	-301.0	64	-210	-346.0	39	-235	-391.0	14	-260	-436.0
113	-161	-257.8	88	-186	-302.8	63	-211	-347.8	38	-236	-392.8	13	-261	-437.8
112	-162	-259.6	87	-187	-304.6	62	-212	-349.6	37	-237	-394.6	12	-262	-439.6
111	-163	-261.4	86	-188	-306.4	61	-213	-351.4	36	-238	-396.4	11	-263	-441.4
110	-164	-263.2	85	-189	-308.2	60	-214	-353.2	35	-239	-398.2	10	-264	-443.2
109	-165	-265.0	84	-190	-310.0	59	-215	-355.0	34	-240	-400.0	9	-265	-445.0
108	-166	-266.8	83	-191	-311.8	58	-216	-356.8	33	-241	-401.8	8	-266	-446.8
107	-167	-268.6	82	-192	-313.6	57	-217	-358.6	32	-242	-403.6	7	-267	-448.6
106	-168	-270.4	81	-193	-315.4	56	-218	-360.4	31	-243	-405.4	6	-268	-450.4
105	-169	-272.2	80	-194	-317.2	55	-219	-362.2	30	-244	-407.2	5	-269	-452.2
104	-170	-274.0	79	-195	-319.0	54	-220	-364.0	29	-245	-409.0	4	-270	-454.0
103	-171	-275.8	78	-196	-320.8	53	-221	-365.8	28	-246	-410.8	3	-271	-455.8
102	-172	-277.6	77	-197	-322.6	52	-222	-367.6	27	-247	-412.6	2	-272	-457.6
101	-173	-279.4	76	-198	-324.4	51	-223	-369.4	26	-248	-414.4	1	-273

Table 16—Fahrenheit Degrees to Centigrade Degrees
F°	C°	F°	C°	F°	C°	F°	C°	F°	C°
-40	-40.0	12	-11.1	64	17.8	116	46.7	168	75.6
-39	-39.4	13	-10.6	65	18.3	117	47.2	169	76.1
-38	-38.9	14	-10.0	66	18.9	118	47.8	170	76.7
-37	-38.3	15	-9.4	67	19.4	119	48.3	171	77.2
-36	-37.8	16	-8.9	68	20.0	120	48.9	172	77.8
-35	-37.2	17	-8.3	69	20.6	121	49.4	173	78.3
-34	-36.7	18	-7.8	70	21.1	122	50.0	174	78.9
-33	-36.1	19	-7.2	71	21.7	123	50.6	175	79.4
-32	-35.6	20	-6.7	72	22.2	124	51.1	176	80.0
-31	-35.0	21	-6.1	73	22.8	125	51.7	177	80.6
-30	-34.4	22	-5.6	74	23.3	126	52.2	178	81.1
-29	-33.9	23	-5.0	75	23.9	127	52.8	179	81.7
-28	-33.3	24	-4.4	76	24.4	128	53.3	180	82.2
-27	-32.8	25	-3.9	77	25.0	129	53.9	181	82.8
-26	-32.2	26	-3.3	78	25.6	130	54.4	182	83.3
-25	-31.7	27	-2.8	79	26.1	131	55.0	183	83.9
-24	-31.1	28	-2.2	80	26.7	132	55.6	184	84.4
-23	-30.6	29	-1.7	81	27.2	133	56.1	185	85.0
-22	-30.0	30	-1.1	82	27.8	134	56.7	186	85.6
-21	-29.4	31	-0.6	83	28.3	135	57.2	187	86.1
-20	-28.9	32	0.0	84	28.9	136	57.8	188	86.7
-19	-28.3	33	0.6	85	29.4	137	58.3	189	87.2
-18	-27.8	34	1.1	86	30.0	138	58.9	190	87.8
-17	-27.2	35	1.7	87	30.6	139	59.4	191	88.3
-16	-26.7	36	2.2	88	31.1	140	60.0	192	88.9
-15	-26.1	37	2.8	89	31.7	141	60.6	193	89.4
-14	-25.6	38	3.3	90	32.2	142	61.1	194	90.0
-13	-25.0	39	3.9	91	32.8	143	61.7	195	90.6
-12	-24.4	40	4.4	92	33.3	144	62.2	196	91.1
-11	-23.9	41	5.0	93	33.9	145	62.8	197	91.7
-10	-23.3	42	5.6	94	34.4	146	63.3	198	92.2
-9	-22.8	43	6.1	95	35.0	147	63.9	199	92.8
-8	-22.2	44	6.7	96	35.6	148	64.4	200	93.3
-7	-21.7	45	7.2	97	36.1	149	65.0	201	93.9
-6	-21.1	46	7.8	98	36.7	150	65.6	202	94.4
-5	-20.6	47	8.3	99	37.2	151	66.1	203	95.0
-4	-20.0	48	8.9	100	37.8	152	66.7	204	95.6
-3	-19.4	49	9.4	101	38.3	153	67.2	205	96.1
-2	-18.9	50	10.0	102	38.9	154	67.8	206	96.7
-1	-18.3	51	10.6	103	39.4	155	68.3	207	97.2
0	-17.8	52	11.1	104	40.0	156	68.9	208	97.8
1	-17.2	53	11.7	105	40.6	157	69.4	209	98.3
2	-16.7	54	12.2	106	41.1	158	70.0	210	98.9
3	-16.1	55	12.8	107	41.7	159	70.6	211	99.4
4	-15.6	56	13.3	108	42.2	160	71.1	212	100.0
5	-15.0	57	13.9	109	42.8	161	71.7
6	-14.4	58	14.4	110	43.3	162	72.2
7	-13.9	59	15.0	111	43.9	163	72.8
8	-13.3	60	15.6	112	44.4	164	73.3
9	-12.8	61	16.1	113	45.0	165	73.9
10	-12.2	62	16.7	114	45.6	166	74.4
11	-11.7	63	17.2	115	46.1	167	75.0

Table 17—Boiling Point of Water (F) as Affected by Pressure.
P inches	t°	P inches	t°	P inches	t°	P inches	t°
16.79	184.0	19.96	192.0	23.59	200.0	27.73	208.0
16.97	184.5	20.1	192.5	23.84	200.5	28.00	208.5
17.16	185.0	20.39	193.0	24.08	201.0	28.69	209.0
17.35	185.5	20.61	193.5	24.33	201.5	28.56	209.5
17.54	186.0	20.82	194.0	24.58	202.0	28.85	210.0
17.74	186.5	21.05	194.5	24.83	202.5	29.15	210.5
17.93	187.0	20.26	195.0	25.0	203.0	29.42	211.0
18.12	187.5	20.49	195.5	25.33	203.5	29.71	211.5
18.32	188.0	21.71	196.0	25.59	204.0	30.00	212.0
18.52	188.5	21.95	196.5	25.86	204.5	30.30	212.5
18.72	189.0	22.17	197.0	26.11	205.0	30.59	213.0
18.92	189.5	22.41	197.5	26.38	205.5	30.89	213.5
19.13	190.0	22.64	198.0	26.64	206.0	31.10	214.0
19.33	190.5	22.89	198.5	26.91	206.5
19.54	191.0	23.11	199.0	27.18	207.0
19.74	191.5	23.36	199.5	27.45	207.5

Table 17—Boiling Point of Water (F) as Affected by Pressure.
P mm	t°	P mm	t°	P mm	t°	P mm	t°
680	96.92	710	98.11	740	99.26	770	100.37
682	97.00	712	98.18	742	99.33	772	100.44
684	97.08	714	98.26	744	99.41	774	100.51
685	97.12	715	98.30	745	99.44	775	100.55
686	97.16	716	98.34	746	99.48	776	100.58
688	97.24	718	98.42	748	99.56	778	100.66
690	97.32	720	98.49	750	99.63	780	100.73
692	97.40	755	98.57	752	99.70	782	100.80
694	97.48	724	98.65	754	99.78	784	100.87
695	97.52	725	98.69	755	99.82	785	100.91
696	97.56	726	98.72	756	99.85	786	100.94
698	97.63	728	98.80	758	99.93	788	101.02
700	97.71	730	98.88	760	100.00	790	101.09
702	97.79	732	98.95	762	100.04	792	101.16
704	97.87	734	99.03	764	100.11	794	101.23
705	97.91	725	99.07	765	100.18	795	101.26
706	97.95	736	99.10	766	100.22	796	101.30
708	98.03	738	99.18	768	100.29	798	101.37

Table 19—Quantity of Rainfall in Cu Ft and U S Gallons per Acre
Inches of rainfall	Cu ft per acre	Gallons per acre	Inches of rainfall	Cu ft per acre	Gallons per acre
0.01	36.3	271.5	0.10	363	2715.4
0.02	72.6	543.5	0.20	726	5430.5
0.03	108.9	814.5	0.30	1089	8146.5
0.04	145.2	1086.5	0.40	1452	10861.5
0.05	181.5	1357.5	0.50	1815	13577.5
0.06	217.8	1629.5	0.60	2178	16292.5
0.07	254.1	1900.5	0.70	2541	19007.5
0.08	290.4	2172.5	0.80	2904	21723.5
0.09	326.7	2443.5	0.90	3267	24438.5
0.10	363.0	2715.5	1.00	3630	27154.5

The U S or Queen Anne gallon used in the foregoing table contains 231 cu in or 0.1368 cu ft. The Imperial or British gallon contains 277.3 cu in. To reduce U S to Imperial gallons multiply by 0.83⅓.

To find the quantity of rainfall per square mile, multiply the quantity per acre by 640.

One inch of rain per acre is at the rate of 113 tons per acre or 7320 tons per sq mi.

Table 20—Depth of Water in a Standard 8-inch Gauge
Corresponding to the Weight of Snow or Rain.
Weight Pounds	.00	.01	.02	.03	.04	.05	.06	.07	.08	.09
	in	in	in	in	in	in	in	in	in	in
0.0	.00	.01	.01	.02	.02	.03	.03	.04	.04	.05
0.1	.06	.06	.07	.07	.08	.08	.09	.09	.10	.10
0.2	.11	.12	.12	.13	.13	.14	.14	.15	.15	.16
0.3	.17	.17	.18	.18	.19	.19	.20	.20	.21	.21
0.4	.22	.23	.23	.24	.24	.25	.25	.26	.26	.27
0.5	.28	.28	.29	.29	.30	.30	.31	.31	.32	.32
0.6	.33	.34	.34	.35	.35	.36	.36	.37	.37	.38
0.7	.39	.39	.40	.40	.41	.41	.42	.42	.43	.44
0.8	.44	.45	.45	.46	.46	.47	.47	.48	.48	.49
0.9	.50	.50	.51	.51	.52	.52	.53	.53	.54	.55

One pound equals 0.5507 in.

Table 21—Weight of a Cubic Foot of Saturated Water
Temp F	Grains Troy	Temp F	Grains Troy	Temp F	Grains Troy	Temp F	Grains Troy	Temp F	Grains Troy	Temp F	Grains Troy
-30	0.095	-5	0.377	20	1.244	45	3.436	70	8.066	95	17.305
-29	0.100	-4	0.391	21	1.301	46	3.563	71	8.329	96	17.812
-28	0.106	-3	0.411	22	1.362	47	3.693	72	8.600	97	18.330
-27	0.112	-2	0.433	23	1.425	48	3.828	73	8.879	98	18.863
-26	0.119	-1	0.455	24	1.490	49	3.965	74	9.165	99	19.407
-25	0.126	0	0.479	25	1.558	50	4.108	75	9.460	100	19.966
-24	0.134	1	0.503	26	1.629	51	4.225	76	9.761	101	20.538
-23	0.141	2	0.529	27	1.703	52	4.407	77	10.072	102	21.123
-22	0.150	3	0.056	28	1.779	53	4.564	78	10.392	103	21.723
-21	0.158	4	0.584	29	1.859	54	4.725	79	10.720	104	22.337
-20	0.167	5	0.613	30	1.942	55	4.891	80	11.056	105	22.966
-19	0.176	6	0.644	31	2.028	56	5.062	81	11.401	106	23.611
-18	0.187	7	0.676	32	2.118	57	5.238	82	11.756	107	14.721
-17	0.197	8	0.709	33	2.200	58	5.420	83	12.121	108	24.946
-16	0.208	9	0.744	34	2.286	59	5.567	84	12.494	109	25.663
-15	0.220	10	0.780	35	2.375	60	5.800	85	12.878	110	26.343
-14	0.232	11	0.818	36	2.466	61	5.999	86	13.272	111	27.066
-13	0.244	12	0.858	37	2.560	62	6.203	87	13.676	112	27.807
-12	0.258	13	0.900	38	2.658	63	6.413	88	14.090	113	28.563
-11	0.272	14	0.943	39	2.759	64	6.630	89	14.515	114	29.338
-10	0.286	15	0.988	40	2.863	65	6.852	90	15.591	115	30.130
-9	0.302	16	1.035	41	2.970	66	7.082	91	15.400	116	30.940
-8	0.318	17	1.084	42	3.082	67	7.317	92	15.858	117	31.768
-7	0.335	18	1.135	43	3.196	68	7.560	93	16.328	118	32.616
-6	0.353	19	1.189	44	3.315	69	7.809	94	16.810	119	33.842

The foregoing values accord with the determinations of Marks and Davis, 1909. Te specific gravity of saturated vapor at 32° F (0° C) is 0.6238; at 50° F (10° C) 0.6256.

Table 22—Expansion of Air from the Freezing to the Boiling Point of Water
t°	V	t°	V	t°	V	t°	V	t°	V	t°	V
32	1000.000	52	1040.700	72	1081.400	92	1122.100	112	1162.800	132	1203.500
33	1002.035	53	1042.735	73	1083.435	93	1124.135	113	1164.835	133	1205.535
34	1004.070	54	1044.770	74	1085.470	94	1126.170	114	1166.870	134	1207.570
35	1006.105	55	1046.805	75	1087.505	95	1128.205	115	1168.905	135	1209.605
36	1008.140	56	1048.840	76	1089.540	96	1130.240	116	1170.940	140	1219.780
37	1010.175	57	1050.875	77	1091.575	97	1132.275	117	1172.975	145	1229.955
38	1012.210	58	1052.910	78	1093.610	98	1134.310	118	1175.010	150	1240.130
39	1014.245	59	1054.945	79	1095.645	99	1136.345	119	1177.045	155	1250.305
40	1016.280	60	1056.980	80	1097.680	100	1138.380	120	1179.080	160	1260.480
41	1018.315	61	1059.015	81	1099.715	101	1140.415	121	1181.115	165	1270.655
42	1020.350	62	1061.050	82	1101.750	102	1142.450	122	1183.150	170	1280.830
43	1022.385	63	1063.085	83	1103.785	103	1144.485	123	1185.185	175	1291.005
44	1024.420	64	1065.120	84	1105.820	104	1146.520	124	1187.220	180	1301.180
45	1026.455	65	1067.155	85	1107.855	105	1148.555	125	1189.255	185	1311.355
46	1028.490	66	1069.190	86	1109.890	106	1150.590	126	1191.290	190	1321.530
47	1030.525	67	1071.225	87	1111.925	107	1152.625	127	1193.325	195	1331.705
48	1032.560	68	1073.260	88	1113.960	108	1154.660	128	1195.360	200	1341.880
49	1034.595	69	1075.295	89	1115.995	109	1156.695	129	1197.395	205	1352.055
50	1036.630	70	1077.330	90	1118.030	110	1158.730	130	1199.430	210	1362.230
51	1038.665	71	1079.365	91	1120.065	111	1160.765	131	1201.465	212	1366.300

Approximate difference for each degree F = 2.035

Table 23—Wind Pressure—Pounds per Square Foot
Ind Vel	0			1			2			3			4			5			6			7			8			9
0	..	.	...	..	.	...	..	.	...	..	.	...	..	.	...	0	.	104	0	.	144	0	.	190	0	.	243	0	.	303
10	0	.	369	0	.	433	0	.	511	0	.	586	0	.	666	0	.	762	0	.	853	0	.	949	1	.	05	1	.	16
20	1	.	27	1	.	38	1	.	50	1	.	63	1	.	76	1	.	90	2	.	04	2	.	19	2	.	34	2	.	48
30	2	.	64	2	.	81	2	.	98	3	.	14	3	.	32	3	.	50	3	.	67	3	.	87	4	.	04	4	.	24
40	4	.	44	4	.	64	4	.	84	5	.	07	5	.	27	5	.	51	5	.	72	5	.	93	6	.	18	6	.	40
50	6	.	66	6	.	89	7	.	12	7	.	40	7	.	64	7	.	88	8	.	14	8	.	43	8	.	69	8	.	95
60	9	.	22	9	.	49	9	.	76	10	.	1	10	.	4	10	.	6	10	.	9	11	.	2	11	.	6	11	.	9
70	12	.	2	12	.	5	12	.	8	13	.	1	13	.	5	13	.	8	14	.	1	14	.	4	14	.	8	15	.	1
80	15	.	5	15	.	8	16	.	2	16	.	5	16	.	9	17	.	3	17	.	6	18	.	0	18	.	4	18	.	8
90	19	.	2	..	.	...	..	.	...	..	.	...	..	.	...	..	.	...	..	.	...	..	.	...	..	.	...	..	.	...

The foregoing are calculated for wind ressure on plane surfaces at right angles to the direction of the wind by the formula $P=.004{\frac {B}{30}}SV^{2}$ . $P=$ pressure in pounds avoirdupois; $S=$ surface in square feet; $V=$ true (or corrected) velocity in mi per hour; $B=$ height of barometer in inches.

Corrected velocites indicated for Robinson anemometer for above table.

Ind Vel	0			1			2			3			4			5			6			7			8			9
0	..	.	...	..	.	...	..	.	...	..	.	...	..	.	...	5	.	1	6	.	0	6	.	9	7	.	8	8	.	7
10	9	.	6	10	.	4	11	.	3	12	.	1	12	.	9	13	.	8	14	.	6	15	.	4	16	.	2	17	.	0
20	17	.	8	18	.	6	19	.	4	20	.	2	24	.	0	21	.	8	22	.	6	23	.	4	24	.	2	24	.	9
30	25	.	7	26	.	5	27	.	3	28	.	0	28	.	8	29	.	6	30	.	3	31	.	1	31	.	8	32	.	6
40	33	.	3	34	.	1	34	.	8	35	.	6	36	.	3	37	.	1	37	.	8	38	.	5	39	.	3	40	.	0
50	40	.	8	41	.	5	42	.	2	43	.	0	43	.	7	44	.	4	45	.	1	45	.	9	46	.	6	47	.	3
60	48	.	0	48	.	7	49	.	4	50	.	2	50	.	9	51	.	6	42	.	3	53	.	0	43	.	8	54	.	5
70	55	.	2	55	.	9	56	.	6	57	.	3	48	.	0	58	.	7	59	.	4	60	.	1	60	.	8	61	.	5
80	62	.	2	62	.	9	63	.	6	64	.	3	65	.	0	65	.	8	66	.	4	67	.	1	67	.	8	68	.	5
90	69	.	2	..	.	...	..	.	...	..	.	...	..	.	...	..	.	...	..	.	...	..	.	...	..	.	...	..	.	...

Table 24

Weight of a cubic foot of water in pounds, av., between the freezing and the boiling point. F

t°	Wt	t°	Wt
32	62.42	130	61.56
40	62.42	140	61.37
50	62.41	150	61.18
60	62.41	150	61.18
70	62.31	170	60.77
80	62.23	180	60.55
90	62.13	190	60.32
100	62.13	190	60.32
110	61.89	210	59.88
120	61.74	212	59.83

Volume of a cubic foot of water from temperature of maximum density to that of boiling point. F

t°	Wt	t°	Wt
39.1	1.00000	131	1.01423
50	1.00025	140	1.01678
59	1.00083	140	1.01678
68	1.00171	158	1.02241
77	1.00286	167	1.02548
86	1.00425	176	1.02872
95	1.00586	185	1.03213
104	1.00767	194	1.03570
113	1.00967	203	1.03943
122	1.01186	212	1.04332

Table 25—Longest Summer Day and Winter Night in Different Latitudes
Read down
Lat	Mar 20	Apr 5	Apr 20	May 5	May 20	June 5	June 20	Lat
0°	12:00	12:00	12:00	12:00	12:00	12:00	12:00	0°
10	12:00	12:11	12:23	12:34	12:44	12:47	12:49	10
20	12:00	12:21	12:47	13:08	13:27	13:34	13:38	20
30	12:00	12:32	13:10	13:42	14:10	14:21	14:27	30
40	12:00	12:43	13:33	14:16	14:53	15:08	15:16	40
45	12:00	12:48	13:43	14:33	15:35	15:31	15:40	45
50	12:00	12:54	13:57	14:48	15:36	15:55	16:05	50
55	12:00	13:07	14:26	15:32	16:28	16:58	17:17	50
60	12:00	13:20	14:55	16:14	17:20	18:00	18:30	60
65	12:00	13:45	15:40	17:25	19:10	20:55	22:40	65
65.5	12:00	14:00	16:00	18:00	20:00	22:00	24:00	65.5
	Sept 20	Sept 5	Aug 20	Aug 5	July 20	July 5	June 20
Read up

Table 26—Mean Barometer at Different Latitudes
Lat	January^[1]		July^[1]		Year^[2]
Lat	mm	in	mm	in	mm	in
75°	758.3	29.86	758.0	29.85	760.0	29.92
70	760.1	29.93	757.6	29.82	758.6	29.86
65	762.0	30.00	757.5	29.82	758.2	29.85
60	760.8	29.96	757.7	29.83	758.7	29.86
55	761.1	29.97	758.1	29.84	759.7	29.91
50	762.3	30.03	758.9	29.92	760.7	29.95
45	763.0	30.04	759.6	29.90	761.5	29.98
40	763.9	30.08	760.0	29.92	762.0	30.00
35	764.8	30.11	759.8	29.91	762.4	30.02
30	765.0	30.11	759.3	29.89	761.7	29.99
25	764.0	30.08	758.5	29.86	760.4	29.94
20	762.3	30.03	758.0	29.84	759.2	29.89
15	760.5	29.24	757.5	29.82	758.3	29.85
10	759.1	29.88	757.7	29.80	757.9	29.84
5	758.2	29.85	758.5	29.86	758.0	29.84
0	758.0	29.84	759.1	29.88	758.0	29.84

↑ ^1.0 ^1.1 Spitaler
↑ Ferrel

The difference in results shown in the foregoing tables are much too great to be attributed merely to observational error. Spitaler’s means were computed mainly from observations made in Europe; Ferrel’s from American data. Means obtained in latitudes lower than Lat 25 are from unknown sources. The following means were obtained at the Key West Weather Bureau Station, Lat 24° 33′.

	mm	in		mm	in		mm	in
Jan.	764.40	30.09	May	761.58	29.98	Sept.	760.90	29.96
Feb.	764.08	30.08	June	761.80	29.99	Oct.	760.38	29.94
March	763.58	30.03	July	763.10	30.04	Nov.	763.05	30.07
April	762.90	30.03	Aug.	762.20	30.01	Dec.	764.34	30.09

Mean for the years 1891-1904, 762.69 mm, 30.03 in.

Table 27—Determination of Speed per Hour According to Distance in Seconds per Mile
Time in		Miles	Time		Miles	Time		Miles
min	sec	per hour	min	sec	per hour	min	sec	per hour
0	20	180.0	0	44	81.8	1	08	52.9
0	21	171.4	0	45	80.0	1	09	52.2
0	22	163.6	0	46	78.3	1	10	51.4
0	23	156.5	0	47	76.6	1	11	50.7
0	24	150.0	0	48	75.0	1	12	50.0
0	25	144.0	0	49	73.5	1	13	49.3
0	26	138.5	0	50	72.0	1	14	48.6
0	27	133.3	0	51	70.6	1	15	48.0
0	28	128.6	0	52	69.2	1	16	47.4
0	29	124.1	0	53	67.9	1	17	46.8
0	30	120.0	0	54	66.7	1	18	46.2
0	31	116.1	0	55	65.5	1	19	45.6
0	32	112.5	0	56	64.3	1	20	45.0
0	33	109.1	0	57	63.2	1	21	44.4
0	34	105.9	0	58	62.1	1	22	43.9
0	35	102.9	0	59	61.0	1	23	43.4
0	36	100.0	0	60	60.0	1	24	42.9
0	37	97.3	1	01	59.0	1	25	42.4
0	38	94.7	1	02	58.1	1	26	41.9
0	39	92.3	1	03	57.1	1	27	41.4
0	40	90.0	1	04	56.2	1	28	40.9
0	41	87.8	1	05	55.4	1	29	40.4
0	42	85.7	1	06	54.5	1	30	40.0
0	43	83.7	1	07	53.7	1	31	39.6

To find the rate of speed in miles per hour divide 3600, the number of seonds in an hour by the number of seconds required to traverse 1 mile. That is, if 1 mile is traversed in 25 seconds, the rate per hour in miles = 3600 ÷ 25 = 144 miles per hour

Table 28—Mean Altitude, in Feet of Clouds at Different Latitudes
Summer
Station	Ci	Ci-St	Ci-Cu	A-St	A-Cu	St-Cu	Nb	Cu top	Cu base	Cu-Nb top	St
Bossekop, 70° N	27,000	22,000	17,500	15,000	11,500	4,500	3,200	7,100	4,300	13,000	2,200
Pavlovsk, 60° N	28,900	26,600	15,000	······	10,000	6,100	······	7,900	5,400	15,400	2,760
Upsala, 60° N	27,000	20,000	21,000	9,100	13,000	5,800	3,900	6,600	4,700	13,000	······
Potsdam, 52° N	29,000	26,000	19,000	10,800	12,000	7,100	5,900	6,900	4,700	13,100	2,230
Trappe, 49° N	29,200	25,600	19,000	12,500	12,000	5,970	3,500	7,100	······	18,000	3,100
Toronto, 44° N	35,800	29,200	29,100	13,900	11,500	6,760	······	······	······	······	······
Blue Hill, 42° N	31,200	33,100	22,000	20,400	12,300	3,800	3,900	9,500	5,800	29,500	1,670
Washington, 39° N	33,800	34,800	29,900	19,000	16,400	9,400	6,300	8,000	3,900	16,300	2,760
Allahabad, 25° N	35,100	······	37,000	······	14,700	······	2,700	······	······	······	······
Manilla, 15° N	36,100	42,500	22,300	14,000	18,700	6,200	4,500	······	······	21,000	3,500
Batavia	37,800	34,500	20,700	······	17,800	······	······	······	······	······	2,300
Winter
Pavlovsk	25,300	23,300	19,600	······	10,400	4,900	······	5,200	3,700	······	3,300
Upsala	22,900	17,700	20,000	13,400	13,600	6,400	3,200	5,000	2,300	17,000	1,600
Potsdam	26,500	25,000	17,700	9,800	11,000	4,700	4,200	5,700	3,200	3,200	2,000
Trappe	27,900	19,100	18,400	12,500	14,000	5,300	3,400	7,800	······	12,600	······
Toronto	32,800	27,900	26,900	13,700	8,200	5,000	······	······	······	······	······
Blue Hill	28,200	29,200	20,200	15,000	12,000	5,200	2,200	5,300	5,000	······	2,000
Washington	31,200	31,300	24,300	15,700	12,500	7,800	5,900	7,500	3,900	12,200	3,700
Manilla	34,800	38,300	21,000	12,500	15,200	7,600	4,900	······	······	10,300	······

Table 29—Constants

Circular Measure
Radius of a circle in seconds of arc	=	206,264	.	8062
Radius of a circle in minutes of arc	=	3437	.	74677
Radius of a circle in degrees of arc	=	57	.	2957795
Circumference of a circle (360°) in seconds	=	1,296,000
Circumference of a circle in minutes =	=	21,600
Ratio of circumference to diameter (2πR)	=	3	.	1415926536

Astronomical
Calendar year	=	365 d, 5 h, 48 min, 46 sec.
Sidereal year	=	365.2563578 days
Sidereal day	=	23 h, 56 min, 41 sec
Mean solar day in sidereal time	=	24 h, 03 min, 56.5 sec
Mean distance of the earth from the sun	=	92,800,000 miles

Physical
Velocity of light per second	=	186,337 miles
Velocity of light per second	=	299,878 kilometers
Velocity of sound per second in dry air at 0° C	=	$1090{\sqrt {1+0.00367t^{\circ }}}$ C feet
Velocity of sound per second in dry air at 32° F	=	$1090{\sqrt {1+0.00204t^{\circ }}}$ F feet

The formula $1090{\sqrt {1+{\tfrac {t^{\circ }}{273}}}}$ for Centigrade, and $1090{\sqrt {1+{\tfrac {t^{\circ }}{459}}}}$ for Fahrenheit scales is practically the same. For all ordinary purposes the value 1110 ft per sec when the temperature of the air is 50° F (30° C) or 1148 ft per sec when the temperature is 86° F (30° C) will meet all requirements.

[p296-1-1] 1.0 ^1.1 Spitaler

[2] Ferrel

[1]

[2]