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WEIGHTS AND MEASURES
PUBLISHED BY J. H. BUTLER
The following pages, taken mainly from the Franklin Written Arithmetic, are intended to present the Metric System of Weights and Measures in a simple and practical way, for the purposes of school instruction.
This system has been presented by itself, unencumbered by comparisons between its units and the units now in common use. Such comparisons are given at the end. This course is believed to be the best ; for pupils will form clear and lasting impressions of the meter, the liter, the gram, their multiples and subdivisions, not by being told how many inches, quarts, or grains they are equivalent to, but by seeing and using the actual measures and weights until he becomes perfectly familiar with them. When a pupil knows the new measures well, he may then begin to make comparisons between the new measures and the old.
A table of specific gravities has been added, with a few examples to illustrate its usefulness, especially when employed in connection with metric weights and measures.
WEIGHTS AND MEASURES.
§ 1. 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.
Note. The word METER means a measure. The standard meter is a 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.
§ 2. 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, a meter 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.
§ 3. One tenth of a meter is a děc'i-meter.
Exercises on the Meter and its subdivisions.
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 ?
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 ?
0. 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?
MEASURES OF LENGTH.
To write Numbers in the Metric System. § 7. 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. $ 8. The abbreviations used in writing expressions of length are: For meters, m; for decimeters, dm; for centimeters, cm; and for millimeters, mm.
$ 9. 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, 0.235 m may be written 2.35 dm, 23.5 or 235 mm So also 728 mm may be written 72.8 cm, 7.28 din, or 0.728 m.
§ 10. Exercises in reading Numbers. Read the following: a. 5 m e. 5.926 m
i. 6.58 dm b. 47 m f. 36 d
j. 3.4 cm c. 3.9 m g. 428
k. 43.7 cm d. 4.21 m h. 23 mm
1. 2.5 m
Examples for the Slate. Change the following to meters : (1.) 1 dm
(4.) 14 (2.) 13 dm
(7.) 1 (5.) 38 cm (3.) 214 dm
(8.) 48 (6.) 529 cm
(9.) 3675 m