These words are prefixed to the units, viz., metre, litre, and We proceed with the other units in the same way, thus: Kilogramme 1,000 grammes 1,000 100 10 We then arrive at our complete table of weights and measures, thus: 1000th 100th 10th (mili) (centi) (deci) Stan- 10 times 100 times 1000 times dard (Deka) (Hecto) (Kilo) mili metre centimetre deci metre METRE: Deka metre Hectometre Kilo metre mili gram centi gram deci gram GRAMME Deka gram Hectogram Kilo gram mili litre centi litre deci litre LITRE : Deka litre Hecto litre Kilo litre This table is all that a child on the Continent has to learn, and when once learned is never forgotten; whereas our children have to learn about a dozen complicated nonsensical tables, most of which are forgotten as soon as school days are over. We may mention that of the denominations given in the above table only the following are in every day use :— Decimal Notation. Before proceeding further it will be well to explain the decimal notation. A decimal number is generally expressed thus: 278-543 that is, the figures are separated by a dot, or "decimal point" as it is generally called. All the numbers to the left of the dot are units, thus in the above example there are 278 units. The figures on the right of the dot are parts of the unit, viz., 10ths, 100ths, 1,000ths, or 10,000ths, according as they stand 1st, 2nd, 3rd, or 4th, after the dot. Any noughts added after the last figure to the right are of no value. Thus 123 divided by 5 is 20.6; 237÷4=59-25; 3÷8=0·375; 121÷2=60·5; 03 ÷ 10 = '003. 1. THE METRE. We now proceed to explain the system in detail, beginning with the metre-the measure of length. We have already explained how this measure is derived. The following is the complete metric table of length. Myria (which we have not given hitherto) is the prefix signifying 10,000 times. It is used chiefly in connection with measures of length and weight, and then very seldom. From the above table it will be seen that Metric measures may be expressed in a variety of ways, thus: The last is the form in which this particular measure would be expressed. (3) (4) 53 2 7 3 in centimetres 53 kilometres 2 hectometres 3 dekametres in Metres in centimetres (5) How many Metres, &c., are there in 73261 centimetres ? (7) Express in terms of a Metre, 31 metres 57 centimetres (8) Find the average of-28 metres; 1 metre 9 decimetres; 6 dekametres 3 metres; 73 hectometres ; 0195 kilometres ; 48 decimetres; and 1500 centimetres. The kilometre is used to express long distances, roads, &c., just as when we speak of miles. The metre is used to measure the length of pieces of cloth, the length of a wall, &c. The centimetre is used to express the width of a piece of cloth, the size of a pane of glass, &c. The millimetre is used to measure the thickness of articles, such as wire, a pane of glass, a sheet of iron, &c. 2. THE MEASURE OF SURFACE. Closely allied to the metre (the measure of length) is the measure of surface, the square metre. This, as its name implies, is a square whose four sides are each a metre in length. The square metre is sub-divided into square decimetres, square centimetres, and square millimetres, and is multiplied into square dekametres, square hectometres, square kilometres, and square myriametres. Therefore, we say that It will be seen that each of these measures is 100 times greater or less than its neighbouring sub-multiple or multiple respectively, thus: Square decimetre (exact size), divided.into 100 square centimetres. Therefore 1 square decimetre is equal to 100 square centimetres. 1 square metre 1 square dekametre 1 square kilometre To read 12 sq. m. 5432, divide each part after the decimal point into two figures (as we are dealing with 100's now, i.e., sq. 10's) thus: 12 sq. m. I 54 sq. dm. I 32 sq. cm. If a single figure, say 3, were added on the right, the above would read 12 sq. m. 54 sq. dm. 30 sq. mm. Exercises. Write in proper form : : (1) 375 sq. m., 32 sq. dm., 33 sq. cm. and 17 sq. mm. (2) 27 sq. m., 5 sq. dm., 2 sq. cm. (3) 54 sq. m., 13 sq. cm., 2 sq. mm. (4) Reduce to square metres, 354 square decimetres 3957. (5) Convert 37.264 sq. m. into decimetres. Square metres are used to express the dimensions of a wall, or the area of a room. Square decimetres are used for smaller surfaces such as a book, a tile, or a brick. Square metres, square dekametres, and square hectometres are used in measuring large plots of landfields, for instance. Square kilometres are used in expressing the area of a country, where we use square miles. In measuring land another measure is used, viz., the are, which is equal to 1 square dekametre or 100 square metres. The only other measures in use derived from the are are the centiare (or 100th part of an are) 1 square metre; and the hectare 100 ares, or 10,000 centiares, or 10,000 square metres. = = 3. MEASURE OF VOLUME OR SOLIDITY. This is what we call in England cubic measure. A cube is a body having six equal sides. A dice, for instance, is a cube. R |