SECTION XIII.

THE METRIC SYSTEM OF WEIGHTS

AND MEASURES.

399. The metric system of weights and measures, now used in the greater part of Europe and coming into use in the United States, is derived from the standard METER.

The standard meter is a

NOTE. The word METER means a measure. certain bar of platinum carefully preserved at Paris. Copies of this bar, made with the utmost precision, have been procured and are carefully preserved by the nations that have adopted the Metric System. The standard meter of the United States is such a copy, and it is kept at Washington. The meter-sticks made for ordinary use are copies of the standard meter.

MEASURES OF LENGTH.

400. The standard unit of length in the metric system. is the meter.

NOTE. The teacher should show the pupil a meter and its subdivisions. If none can readily be obtained, one can easily be made from the decimeter represented on the next page. This meter may be divided into decimeters and centimeters. From this measure the pupils can easily make their own of paper or wood.

401. One tenth of a meter is a děc'i-meter.

NOTE. The prefix deci- means one tenth of.

402. One hundredth of a meter is a cen'ti-meter.

NOTE. The prefix centi- means one hundredth of.

403. One thousandth of a meter is a milli-meter.

NOTE. The prefix milli- means one thousandth of.

404. Exercises on the Meter and its subdivisions.

a. How many meters long is the room? How many meters wide?

b. How many decimeters long is the table?

c. How many decimeters wide is the door?

d. How many centimeters long and wide is your slate? the window-pane? etc.

e. How many millimeters apart are two lines on a sheet of writing-paper?

f. How many millimeters thick is your slate-frame? your ruler? etc.

g. How many millimeters are there in one centimeter ?

h. How many centimeters are there in one decimeter?

i. How many decimeters are there in one meter?

j. How many millimeters are there in one decimeter? in one meter?

k. How many centimeters are there in 37 millimeters, and how many millimeters remain ?

1. How many decimeters are there in 84 centimeters, and how many centimeters remain?

ONE DECIMETER.

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CENTIMETERS.

m. How many meters are there in 347 centimeters, and how many centimeters remain ?

n. In measuring the length of the room, did you find it to be an exact number of meters long?

o. If not, how many decimeters do you find in the remainder? Do you find an exact number of decimeters?

p. If there is still a remainder, how many centimeters do you find in it?

To write Numbers in the Metric System.

405. To express a length in meters and parts of a meter, we write whole meters in the units' place, decimeters in the tenths' place, centimeters in the hundredths' place, and millimeters in the thousandths' place.

Thus, if a room is found to be 8 meters 6 decimeters 9 centimeters long, we write :

Length of the room = 8.69 meters.

2 decimeters 3 centimeters 5 millimeters is written :

0.235 meters.

406. The abbreviations used in writing expressions of length are: For meters, m; for decimeters, dm; for centimeters, cm; and for millimeters, mm.

407. Lengths may be expressed in other denominations as well as in meters, by putting the decimal point at the right of the place of the required denomination, and writing the proper name or abbreviation after the figures.

Thus, 0.235m may be written 2.35 dm, 23.5 cm, or 235mm. So also 728 m may be written 72.8 cm,

mm

7.28 dm or 0.728 m.

409. Examples for the Slate.

Change the following to meters:

Multiples of the Meter.

410. Besides the meter and its subdivisions, there are longer measures, which are multiples of the meter.

411. The děk'a-meter is ten times as long as the meter. NOTE. The prefix deka- means tenfold.

412. The hěk'to-meter is a hundred times as long as the meter.

NOTE. The prefix hekto- means a hundredfold.

413. The kilo-meter is a thousand times as long as the meter.

NOTE. The prefix kilo- means a thousandfold.

414. The myria-meter is ten thousand times as long as the meter.

NOTE. The prefix myria- means ten thousandfold.

NOTE. Of these longer measures, the kilometer is used in measuring distances on roads, canals, rivers, etc. The other measures are much less frequently used; the myriameter hardly ever.

415. Exercises on the Multiples of the Meter.

a. Measure off a string ten meters long. What name is given to the length of this string?

NOTE. The string may be used in measuring distances. For this purpose it will be well to make knots at the end of each meter.

b. Measure in dekameters and meters the length and breadth of the school-yard; of a garden; of a field, etc.

c. Measure off in the street, or other convenient place, a distance of 10 dekameters. What name is given to this distance?

d. Walk from the beginning to the end of the distance thus measured off, and count your paces. How many of your paces make a hektometer?

e. How many of your paces would make a kilometer?

f. How many kilometers from your home to the school-house?

g. How long does it take you to walk a kilometer?

h. How many kilometers can you walk in an hour?

i. If 1500 of your paces make a kilometer, how many make a dekameter?

416. To express distances in meters and multiples of a meter, we write meters in the units' place, dekameters in the tens' place, hektometers in the hundreds' place, and so on.

417. To express a distance in kilometers, we write kilometers in the units' place, and then hektometers, dekameters, and meters will be written in the tenths', hundredths', and thousandths' places respectively.

Thus, if the distance from one town to another is found to be 9780 meters, the usual form of writing would be 9.78 kilometers.

NOTE. The greatest distances are usually expressed in kilometers. Thus, the distance of the earth from the sun is about 149000000 kilometers.

418. The abbreviations used in writing are: For the dekameter, Dm; for the hektometer, Hm; and for the kilometer Km.