325

THE METRIC SYSTEM.

372. THE METRIC SYSTEM of Weights and Measures is based upon the decimal system of notation.

It was authorized to be used in the United States, and its use introduced into some departments of public service, in 1866, by an Act of Congress.

373. The Principal Units, or those from which the others are derived, are:

The METER, which was intended to be, and is nearly, one ten-millionth of the distance on the earth's surface from the equator to the pole.

The SQUARE METER, which is the square whose side is one meter; and the ARE (pronounced air), which is the square whose side is ten meters.

The CUBIC METER, or STERE (pronounced stair), which is the cube whose edge is one meter; and the LITER (pronounced leeter), which is one thousandth of a cubic meter.

The GRAM, which is the weight, in vacuum, of a cubic centimeter of distilled water, at the greatest density.

374. The HIGHER DENOMINATIONS are expressed by prefixing to the name of the principal unit,

DEKA, 10; HECTO, 100; KILO, 1000; MYRIA, 10,000; and the LOWER DENOMINATIONS by prefixing

DECI, 10th; CENTI, 100th; MILLI, 1000th.

NOTE. Kilo is pronounced kilo, and Deci, dès'é.

NOTE 1. The meter is used as the unit of measure in measuring cloth, and common lengths and distances, and the kilometer in measuring long distances, as the length of roads and rivers, distances between cities, etc.

NOTE 2. A meter is very nearly 3 feet, 3 inches, and 3 eighths of an inch in length; and a kilometer is about 200 rods, or g of a mile.

100

376. MEASURES OF SURFACE.

sq. millimeters (mm2.)=1 sq. centimeter, cm2.,=.00155 sq. in. 100 sq. centimeters, 1 sq. decimeter, dcm2.,

.1076 sq. ft.

100 cen'tiares (ca.), or sq. me.,

100 ares,

1 hectare, ha.,

2.471 acres.

NOTE 1. The square meter is used in general in measuring surfaces. The are is the principal unit in measuring land; and the hectare is also taken as a unit of the same kind of measurement.

NOTE 2. A square meter is about 1 square yards, and an are nearly 4 square rods.

377. MEASURES OF VOLUME.

1000 cu. millimeters, (mm3.), 1 cu. centimeter, cm3., .061 cu. in.

1000 cu. centimeters,

1000 cu. decimeters,

1 cu. decimeter, dcm3., 61.022 cu. in. 1 CU. METER, m3., 1.308 cu. yd.

Also,

10 dec'isteres (dcs.) =1 STERE, or cu. meter, st.,=1.308 cu. yd.

NOTE 1. The cubic meter is used in general in measuring volume, and the stere in estimating wood.

NOTE 2. The liter is used in measuring liquids; it is about 11 liquid quarts, or of a dry quart; 1000 liters are equal to 1 cubic meter.

NOTE 3. The hectoliter, or for brevity hecto, is generally taken as the unit in measuring dry articles, such as grains, salt, etc., and is about 25 bushels, or of a barrel.

NOTE 1. The gram is the unit in weighing gold, silver, and jewels, in mixing medicines, determining postage, etc.; the kilogram, or, for brevity, kilo, is the ordinary weight of commerce; and the tonneau, or metric ton, is used in weighing coal, hay, and all very heavy articles.

NOTE 2. A kilo is about 2 avoirdupois pounds, or 2.68 Troy pounds; and a metric ton a little more than 2200 avoirdupois pounds.

379. Equivalents of denominations of common weights and measures in metric denominations are exhibited in the following

The numbers in the tables are determined approximately, but are sufficiently exact for all ordinary purposes.

380. In expressing Metric Weights and Measures the decimal point, as in United States money, is placed between the unit, and its subdivisions decimally written.

One, two, or three orders of figures are required to express

each metric denomination, lower than the unit, according as the scale is 10, 100, or 1000. Thus,

We write according to the unit and scale, 6 kilometers, 3 dekameters, 5 meters, 7 decimeters, and 2 centimeters, as 6.03572 kilometers, or 6035.72 meters.

16 hectares, 35 ares, and 25 centiares, as 16.3525 hectares, or 1635.25 ares.

41 cubic meters, 5 cubic centimeters, and 428 cubic millimeters, as 41.000005428 cubic meters.

381. The metric system is made very simple of application by the practice of using in general but a few of its denominations. Thus,

Of LENGTHS, the meter, or kilometer; of SURFACES, the square meter, are, or hectare; of VOLUME, the cubic meter or stere, the liter, or hectoliter; and of WEIGHTS, the gram, kilo, or metric ton.

382. In a metric expression, a decimal part, if any, may be either read as a decimal of the unit; or, which is better, as a number of the lowest metric denomination denoted. Thus,

15.75 meters may be read as fifteen meters and seventy-five centimeters.

25.0035 hectares, as twenty-five hectares and thirty-five centiares.

EXERCISES.

1. Copy and read 45.63 meters.

This mixed number may be read forty-five and sixty-three hundredths meters, or forty-five meters and sixty-three centimeters.

10. Write in figures eight meters, four centimeters.

Regarding a meter the unit, we write 8, which will denote the number of meters, as the integral part of a decimal expression, and place the decimal point. Then, as there are no decimeters, we write 0 in the place of decimeters, and 4, which will denote the number of centimeters, in the place of centimeters, and have as the required expres sion, 8.04 me.

Write in figures,

11. Twenty-four meters and three centimeters. Ans. 24.03 me. 12. Sixteen meters and twenty-one millimeters.

13. As hectares, thirty-five hectares, four ares, and fourteen centiares. Ans. 35.0414 ha.

14. Fifteen ares and seventy-five centiares.

15. Forty-five square meters, three square decimeters, and forty-one square centimeters. Ans. 45.0341 m2. 16. One hundred square meters and fifty-six square millimeAns. 100.000056 m2.

ters.

17. Three cubic meters and sixty-two cubic centimeters.

Ans. 3.000062 m3.

18. Sixty-three liters, four deciliters, and five centiliters.

Ans. 63.45 lt.

Ans. 5.7 st.

19. Five steres and seven decisteres. 20. Two hundred twenty-five kilos and seventy-two grams.

Ans. 225.075 k.

21. As tonneaux, three tonneaux, seven quintals, and five kilos.

22. Reduce 9.607 kilometers to meters.

Ans. 3.705 t.

Since in 1 kilometer there are 1000 meters, in 9.607 kilometers there must be 9.607 times 1000 meters, or 9607 meters.

23. In 568 ares, how many hectares?

Since there is 1 hectare in 100 ares, there are as many hectares in 568 ares as 100 ares are contained times in 568 ares, or 5.68 hectares. 24. Reduce 15.045 m2. to square centimeters.

Ans. 150450 cm2.

25. In 185.67 liters, how many hectoliters? Ans. 1.8567 lt.

26. In 43.61 kilograms, how many grams ? Ans. 43610 gm. 27. In 1064.000 cm3, how many cubic meters?

28. In 3.05 m3, how many cubic millimeters?

Ans. 1.064 m3.

Ans. 3050000000 mm3.

29. Add 31.04 meters, 67.05 meters, and 11.05 meters.

Ans. 109.14 me.

30. Find the sum of 416.54 kilos, 312.065 kilos, and 100.5

kilos.

Ans. 829.105 k.