76 



THE POPULAR EDUCATOR. 



LESSONS IN ARITHMETIC. XLVIII. 



THE METKIC SYSTEM. 



THE advantage of adopting the Metric System of weights 

 and measures in this country has become a question of con- 

 siderable public interest. By an Act of Parliament passed in 

 1864, the use of the Metric System was rendered legal. In the 

 session of 1868 a bill for rendering its use compulsory was read 

 a second time in the House of Commons by a majority of 219 to 

 C7, and was only withdrawn out of deference to a request on the 

 part of the Government not to press it forward until the com- 

 pletion of the labours of a Eoyal Commission then sitting on the 

 currency question. Petitions in its favour have been, presented 

 to Parliament by the Associated Chambers of Commerce, and at 

 several meetings of the International Statistical Congress, and 

 of the British Association for the Advancement of Science, 

 resolutions have been passed recommending its general adop- 

 tion. Finally, it may be stated that the Metric System has 

 been already accepted, either wholly or in part, by 360 millions 

 of people, and that in every country there exists a strong and 

 growing feeling that an international system, founded on 

 rational principles, such as the metric, would be of inestimable 

 advantage to science, commerce, and education. 



Under these circumstances, it is proposed to give in the pages 

 of the POPULAR EDUCATOR a familiar account of the Metric 

 System. As the catechetical method of instruction presents 

 many advantages in expounding the principles of a scientific 

 system, the form of question and answer has been adopted as 

 follows: 



Q. What is the Metric System ? A. The Metric System is a 

 rational system of measures and weights designed for the use of 

 all civilised nations. 



Q. Why do you call it a rational system ? A. For the fol- 

 lowing reasons : Firstly, Because in all its multiples and sub- 

 divisions it follows the decimal arrangement. Secondly, Because 

 all its parts, whether of length, surface, volume, or weight, 

 being directly derived from the unit of length, are mutually 

 dependent. Thirdly, Because the names given to the measures 

 and weights are well fitted for adoption into all civilised lan- 

 guages. 



Q. Why is the system called Metric ? A. Because it is 

 founded on the meter as the unit of length. 



Q. What is the meter? A. The meter is a line equal in 

 length to the ten-millionth part of the earth's meridian, mea- 

 sured from the pole to the equator. 



Q. Can you give an account of the names by which the various 

 measures and weights of the Metric System are described ? 

 A. Yes, very simply. There are four prefixes derived from the 

 Greek language, and three from the Latin, which, placed before 

 the unit of each denomination, constitute the entire language 

 of the Metric System. They are as follow : 



From the Greek Myria, signifying ten thousand times. 

 Kilo, one thousand times. 



Hecto, 

 Beka, 



From the Latin Deci, 

 Centi, 

 Milli, 



one hundred times, 

 ten times, 

 one tenth part, 

 one hundredth part. 

 one thousandth part. 



Q. Can you give an example of the application of these prin- 

 ciples ? A. Yes, by repeating the 



TABLE OF LINEAR MEASURE. 



Myriameter = 10,000 meters. 

 Kilometer = 1,000 

 Hectometer = 100 

 Dekameter = 10 



METER = 1 meter. 

 Decimeter = -f s of a meter. 

 Centimeter = T ij 

 Millimeter = To 1 ?, 



Q. Has the length of the meter ever been exactly determined 

 in English measures ? A. Yes, by Captain Kater, in the year 

 1818, acting under the authority of a Eoyal Commission, and 

 the permission of the French Government. 



Q. What was the length thus found ? A. The length thus 

 found was 39-37079 inches. 



Q. Without reference to an exact standard, how would you 

 instruct a common carpenter to make a meter? A. I would 

 tell him to cut a slip of wood of the length 3 feet 3 inches, 

 3 eighths, then divide the whole into ten equal parts, and each 

 of these into ten equal parts. I would then have a meter, 



sufficiently correct for all practical purposes, divided into 

 decimeters and centimeters. 



Q. Can you give a simple relation in whole numbers between 

 the principal linear measures of the English and Metric Systems ? 

 A. The following relations are very simple, and sufficiently 

 exact for practical purposes, the latter especially : 10 meters = 

 11 yards ; and 64 meters = 70 yards = 210 feet. 



Q. Proceeding from linear measure, can you give an account 

 of metric land measure? A. Yes, the unit of land measure is 

 the ar, and the table of land measure is formed in the same 

 manner as before, by the addition of the metric prefixes. 



Q. What is the ar ? The ar is a square standing on a deka- 

 meter, and is therefore equal to one hundred square meters or 

 centiars. 



Q. Repeat the table of land measure. A. The table repeated 

 in full is as follows : 



TABLE OF LAND MEASURE. 

 Myriar = 10,000 ars. , AE = 1 ar. 



Kilar = 1,000 Deciar = }$ of an ar. 



Hectar = 100 Centiar = T J S 



Dekar = 10 Milliar = TOSS 



Q. Why do you say repeated in full ? A. Because in those 

 countries which have adopted the Metric System, three denomina- 

 tions only are ever used in practice, land being always mea- 

 sured in hectars, ars, and centiars. 



Q. What is the exact value of an ar and of a hectar ? A. An 

 ar is equal to 119*60333 square yards; a hectar is equal to 

 2'47114 acres. 



Q. Can you state the value of a hectar approximately in Eng- 

 lish measures ? A. Yes, a hectar is very nearly equal to 10 

 roods or 2 acres. 



Q. Is this value of the hectar too great or too small ? A. It 

 is too great. A more exact relation is the following : 40 

 hectars = 99 acres. 



Q. This seems to furnish an easy rule for turning hectars intc 

 acres. A. Yes; consider each hectar as 10 roods, and from the 

 result deduct 1 per cent. 



Q. Passing from land measure, can you give an account of 

 cubic measure ? Yes ; the unit of volume or cubic measure is 

 ^ohe liter, and the table is formed in the usual way. 



Q. What is the liter ? The liter is a volume equal to the con- 

 tents of a cube each of whoso sides is a decimeter. 



Q. Eepeat the table of cubic measure. A. : 



TABLE OF CUBIC MEASURE. 



Myrialiter = 10,000 liters. ! LITER = 1 liter. 

 Kiloliter 1,000 Deciliter = & ol a liter. 



Hectoliter = 100 Centiliter = T Jj 



Dekaliter = 10 Milliliter = rr. 1 ,^ 



Q. Have you any observations to make on these measures ? 

 Yes ; the first two namely, the myrialiter and kiloliter are 

 rarely if ever used in practice. The hectoliter is practically 

 the unit of corn measure. 



Q. What is the exact value of the liter to cubic inches ? A. 

 The liter is equal to 61-02705 cubic inches. 



Q. How do you prove this P The length of a decimeter is 

 3'937079 inches ; by calculating the cube of this number by 

 continued multiplication, we arrive at the number 61 '02705. 



Q. Can you give any simple relation connecting the cubic 

 measure of the Metric System with English liquid measure ? 

 A. The following is very nearly true, and is sufficiently correct 

 for all practical purposes : 1 hectoliter = 22 gallons. 



Q. Can you give any other ? A. Yes ; the following is very 

 simple, but not so exact as the last : 1 gallon = 4J liters. 



Q. Passing from cubic measure, can you inform me as to the 

 unit of weight of the Metric System ? A. The gram, the unit of 

 weight of the Metric System, is the weight of a cubic centi- 

 meter of pure water taken at its greatest density. 



Q. What do you mean by water at its greatest density ? A. 

 The density of water, or weight which fills a given bulk, varies 

 with its temperature or degree of heat. The greatest density 

 corresponds to the temperature of 40 degrees. 



Q. The unit of weight being thus determined, how do you 

 state the table of metric weight ? A. As follows : 



