CHAPTER XI THE METRIC SYSTEM THE metric system of weights and measures originated in France about 1800. Since that time its use has become universal in scientific measurements, and it is established as the commercial system in a large part of the civilized world. The United States made the metric system "lawful" in 1866, and obligatory in Porto Rico and the Philippine Islands about 1900. The advantage of the metric system lies in the fact that it is based on a decimal scale. The only multiplier or divisor used is 10 or a power of 10. Reductions are made by merely changing the position of the decimal point. 99. Definitions of Terms. The unit of length is the meter. It is approximately 39.37 inches. The unit of capacity is the liter (lēter), which is equivalent to a cube having an edge one-tenth of a meter long. The unit of weight is the gram, which is the weight of a cube of distilled water having an edge of of a meter. 100. Fractions and Multiples of Units. Fractional parts of these units are expressed by Latin prefixes, as follows: Multiples of the units are expressed by Greek prefixes, as follows: The prefixes and their meanings should be learned. In the tables which follow the most commonly used measures are printed in heavy type. 101. Measures of Length. 10 millimeters (mm.) 10 centimeters 10 decimeters 10 meters 10 dekameters 10 kilometers = 1 centimeter (cm.). = 1 decimeter (dm.) = 1 meter (m.) = 1 dekameter (Dm.). The following rule is 10 centimeters, or 1 decimeter, long. The smallest subdivisions are millimeters. CENTIMETERS INCHES The meter is used for measuring certain merchandise and for other purposes where the foot and yard would be used in the English system. It is also used in engineering and constructions. The kilometer is used for measuring distances which would be expressed in the English system in miles. The centimeter is used instead of the inch in certain measurements such as in expressing the size of paper and books. The millimeter is used for fine measurements in machine construction and similar work. 3. Reduce 5,427 cm. to m.; Km. 4. Reduce 4.72 Km. to dm. 5. Reduce .034 m. to Km. 6. Reduce .0842 Km. to m. The advantage of the metric system is well illustrated in the measurement of distances. A distance of 1 kilometer, 6 dekameters, 4 decimeters, 8 centimeters, is expressed as 1,060.48 meters, and is read “ten hundred sixty meters and forty-eight centimeters, just as we would say "ten hundred sixty dollars and forty-eight cents." 102. Measures of Area. The table of area is formed by squaring the units of length, as in the English system. 100 sq. millimeters (sq. mm.) = 1 sq. centimeter (sq. cm.). The abbreviations of the system are not uniform, mm.2 is frequently used instead of sq. mm.; etc. 103. Land Measure. The are is ten meters square. It has a side about 33 feet long. The hektare, containing 100 ares, is about 2 acres. The hektare is the unit of land measure. A quarter section (160 acres) is almost exactly 64 hektares. Examples. 1. Reduce .4367 sq. m. to sq. Hm. 1. Reduce 427 sq. m. to sq. Dm; sq. Hm. 2. Reduce 37 sq. cm. to sq. m.; sq. mm. 4. Reduce .1 sq. m. to sq. cm.; sq. mm. 104. Measures of Volume. The cubic meter is the unit of volume. It is sometimes called the stere. 1,000 cu. millimeters (cu. mm.) = 1 cu. centimeter (cu. cm.) 1,000 cu. centimeters 1,000 cu. decimeters 1,000 cu. meters 1,000 cu. dekameters 1,000 cu. hektometers = = 1 cu. decimeter (cu. dm.) 1 cu. meter (cu. m.) = 1 cu. dekameter (cu. Dm.) = 1 cu. hektometer (cu. Hm.) = 1 cu. kilometer (cu. Km.) The abbreviations mm.3, cm.3, etc., are sometimes used. Examples. 1. Reduce 4,386 cu. m. to cu. Dm. The unit of capacity is the liter, which is a cubic decimeter. It equals 1.05668 liquid quarts or 0.9081 dry quart. 10 milliliters (ml.) = 1 centiliter (cl.) 1 deciliter (dl.) 1 liter (1.) 1 dekaliter (Dl.) = 1 hektoliter (Hl.) = 1 kiloliter (Kl.) The liter serves the same purpose in measuring capacities as the quart and gallon. The hektoliter is used for measuring quantities commonly measured by the bushel in countries where the English system is used. Oral Work 1. Reduce 427 1. to Dl.; Hl.; cl. 2. Reduce .043 Dl. to dl.; cl. 3. Reduce .04278 Kl. to 1.; dl.; Hl. 106. Measures of Weight. The gram is the unit of weight. A liter of water weighs a kilogram, or 1000 grams. 10 milligrams (mg.) = 1 centigram (cg.) 1. Reduce 4,736 g. to Kg.; cg.; mg. 2. Reduce .03 cg. to mg.; g.; Dg. 3. Reduce .07428 Kg. to g.; dg.; cg. The kilogram and the "half kilo " are the common measures used in trade. The metric ton or tonneau (1,000 kilograms) is used for larger weights. 107. Comparative Table of Weights and Measures. The following table of comparisons will be useful in reducing measurements stated in the English system to equivalent metric measures, and vice versa. It is not to be memorized. 2.54001 centimeters. = .304801 meter. = .914402 meter. = = €1.60935 kilometers. = 6.452 square centimeters. = .09290 square meter. = = = .8361 square meter. 2.59 square kilometers. = 16.3872 cubic centimeters. |
