Square Measure.-Measures of Surface. 144 square inches, or 183.35 circular inches = 1 square foot. An acre equals a square whose side is 208.71 feet. Circular Inch; Circular Mil.-A circular inch is the area of a circle 1 inch in diameter = 0.7854 square inch. 1 square inch = 1.2732 circular inches. A circular mil is the area of a circle 1 mil, or .001 inch in diameter. 10002 or 1,000,000 circular mils = 1 circular inch. 1 square inch = 1,273,239 circular mils. The mil and circular mil are used in electrical calculations involving the diameter and area of wires. Solid or Cubic Measure.-Measures of Volume. 1728 cubic inches = 1 cubic foot. 27 cubic feet = 1 cubic yard. 1 cord of wood a pile, 4 x 4 x 8 feet 128 cubic feet. A gallon of water at 62° F. weighs 8.3356 lbs. The U. S. gallon contains 231 cubic inches; 7.4805 gallons = 1 cubic foot. A cylinder 7 in. diam. and 6 in. high contains 1 gallon, very nearly, or 230.9 cubic inches. The British Imperial gallon contains 277.274 cubic inches 1.20032 U. S. gallon, or 10 lbs. of water at 62° F. = The Miner's Inch.-(Western U. S. for measuring flow of a stream of water). The term Miner's Inch is more or less indefinite, for the reason that California water companies do not all use the same head above the centre of the aperture, and the inch varies from 1.36 to 1.73 cubic feet per minute each; but the most common measurement is through an aperture 2 inches high and whatever length is required, and through a plank 14 inches thick. The lower edge of the aperture should be 2 inches above the bottom of the measuring-box, and the plank 5 inches high above the aperture, thus making a 6-inch head above the centre of the stream. Each square inch of this opening represents a miner's inch, which is equal to a flow of 1 cubic feet per minute. Apothecarics' Fluid Measure. 60 minims = 1 fluid drachm. In the U. S. a fluid ounce is the 128th part of a U. S. gallon, or 1.805 cu.*ins. It contains 456.3 grains of water at 39° F. In Great Britain the fluid ounce is 1.732 cu. ins, and contains 1 ounce avoirdupois, or 437.5 grams of water at 62° F. 2 pints 1 quart. Dry Measure, U. S. 8 quarts 1 peck. 4 pecks = 1 bushel. The standard U. S. bushel is the Winchester bushel, which is in cylinder form, 181⁄2 inches diameter and 8 inches deep, and contains 2150.42 cubic inches. A struck bushel contains 2150.42 cubic inches = 1.2445 cu. ft.; 1 cubic foot = 0.80356 struck bushel. A heaped bushel is a cylinder 181⁄2 inches diameter and 8 inches deep, with a heaped cone not less than 6 inches high. It is equal to 14 struck bushels. The British Imperial bushel is based on the Imperial gallon, and contains 8 such gallons, or 2218.192 cubic inches = 1.2837 cubic feet. The English quarter 8 Imperial bushels. Capacity of a cylinder in U. S. gallons =square of diameter, in inches X height in inches X .0034. (Accurate within 1 part in 100,000.) Capacity of a cylinder in U. S. bushels = square of diameter in inches X height in inches x .0003652. Shipping Measure. Register Ton.-For register tonnage or for measurement of the entire internal capacity of a vessel : 100 cubic feet = 1 register ton. This number is arbitrarily assumed to facilitate computation. Carpenter's Rule.-Weight a vessel will carry = length of keel X breadth at main beam × depth of hold in feet ÷95 (the cubic feet allowed for a ton). The result will be the tonnage. For a double-decker instead of the depth of the hold take half the breadth of the beam. 2000 pounds 2204.6 pounds = 1 pound, lb. = 1 quarter, qr. = 1 hundredweight, cwt. = 112 lbs. = 1 net, or short ton. = 1 metric ton. 1 stone = 14 pounds; 1 quintal = 100 pounds. The drachm, quarter, hundredweight, stone, and quintal are now seldom used in the United States. Troy weight is used for weighing gold and silver. The grain is the same in Avoirdupois, Troy, and Apothecaries' weights. A carat, used in weighing diamonds 3.168 grains = .205 gramme. To determine whether a balance has unequal arms.After weighing an article and obtaining equilibrium, transpose the article and the weights. If the balance is true, it will remain in equilibrium; if untrue, the pan suspended from the longer arm will descend." To weigh correctly on an incorrect balance.-First, by substitution. Put the article to be weighed in one pan of the balance a counterpoise it by any convenient heavy articles placed on the o Remove the article to be weighed and substitute for it standar until equipoise is again established. The amount of these weig weight of the article. Second, by transposition. Determine the apparent weight of t as usual, then its apparent weight after transposing the article weights. If the difference is small, add half the difference to th of the apparent weights to obtain the true weight. If the differ per cent the error of this method is 1 part in 10,000. For larger dif or to obtain a perfectly accurate result, multiply the two apparent together and extract the square root of the product. 365 days, 5 hours, 48 minutes, 48 seconds = 1 year. By the Gregorian Calendar every year whose number is divisible by leap year, and contains 366 days, the other years containing 365 da cept that the centesimal years are leap years only when the number year is divisible by 400. The comparative values of mean solar and sidereal time are shown following relations according to Bessel: 365.24222 mean solar days = 366.24222 sidereal days, whence Inlogo 1 mean solar day = 1.00273791 sidereal days; 1 sidereal day = 0 99726957 mean solar day; 24 hours mean solar time = 24h 3m 568.555 sidereal time; 24 hours sidereal time = 23h 56m 48.091 mean solar time, whence 1 mean solar day is 3m 558.91 longer than a sidereal day, reckon mean solar time. In board measure boards are assumed to be one inch in thickness. obtain the number of feet board measure (B. M.) of a board or stic square timber, multiply together the length in feet, the breadth in feet, the thickness in inches. To compute the measure or surface in square feet.-W all dimensions are in feet, multiply the length by the breadth, and the duct will give the surface required. When either of the dimensions are in inches, multiply as above and div the product by 12. When all dimensions are in inches, multiply as before and divide prod by 144. To compute the volume of round timber.-When all dim sions are in feet, multiply the length by one quarter of the product of t mean girth and diameter, and the product will give the measurement cubic feet. When length is given in feet and girth and diameter in inch divide the product by 144; when all the dimensions are in inches, divide 1728. To compute the volume of square timber.-When all dime sions are in feet, multiply together the length, breadth, and depth; th product will be the volume in cubic feet. When one dimension is given inches, divide by 12; when two dimensions are in inches, divide by 144; whe all three dimensions are in inches, divide by 1728. les placed on the other pan. tute for it standard weights Ount of these weights is the parent weight of the article sposing the article and the he difference to the smaller ight. If the difference is 2 000. For larger differences, y the two apparent weights duct. B. WEIGHTS AND MEASURES. Contents in Feet of Joists, Scantling, and Timber. 22222 37 65 56 70 72 84 96 75 93 112 100 117 196 12 18 24 30 36 40 42 36 45 54 63 24 36 48 60 72 75 84 54 72 98 112 126 140 33 37 93 103 90 100 110 120 163 187 210 233 257 280 303 144 168 192 216 240 264 160 173 187 192 208 224 224 243 261 240 260 280 327 312 336 392 425 457 inch in thickness. To f a board or stick of ne breadth in feet, and quare feet.-Wher breadth, and the proy as above and divide e and divide product When all dimenthe product of the he measurement in ! diameter in inches, in inches, divide by When all dimenth, and depth; the ension is given in divide by 144; when 196 224 252 280 308 336 364 392 261 294 327 FRENCH OR METRIC MEASURES. 1 square centimetre = .155 square inch. 6.452 square centimetres = 1 square inch. 1 square millimetre = .00155 sq. in. 1973.5 circ. m 645.2 square millimetres = 1 square inch. = 2.4711 acres = 1 cubic decimetre = 61.023 66 = 1.05671 quarts, 1 hectolitre or decistere 3.5314 cubic feet = 2.8375 bushels 1 stere, kilolitre, or cubic metre 1.308 cubic yards = 28.37 bushels BRITISH and U. S. 61.023 cubic inches, .03531 cubic foot, .2642 gallon (American), 2.202 pounds of water at 62° F. Mr. O. H. Titmann, in Bulletin No. 9 of the U. S. Coast and Geodetic Su vey, discusses the work of various authorities who have compared the ya and the metre, and by referring all the observations to a common standar has succeeded in reconciling the discrepancies within very narrow limit The following are his results for the number of inches in a metre accordin to the comparisons of the authorities named: |