Our System of Weights and Measures 



i6 5 



Mr Bell: There is a simple relation be- 

 tween volume and weight: one cubic 

 centimeter of water weighs one gram. 

 That fact remembered is the key to the 

 whole subject. 



Now if you want to calculate the 

 weight of any other substance you have 

 simply to express its volume in cubic 

 centimeters and multiply that by the 

 specific gravity of the substance. Here is 

 a piece of steel 10 centimeters long, one 

 centimeter wide, and one-tenth of a centi- 

 meter thick (one millimeter). What is 

 its weight? 



Now you first find out the cubical con- 

 tents of this piece of steel by multiplying 

 together the length, breadth, and thick- 

 ness expressed in centimeters so as to 

 have the answer in cubic centimeters. It 

 is io centimeters long and i centimeter 

 wide ; io times i is io. It has a surface 

 of io square centimeters, it is one-tenth 

 of a centimeter thick. One-tenth of io is 

 i ; that is, its volume is I cubic centi- 

 meter. Now multiply this by the specific 

 gravity of steel and this will give you its 

 weight expressed in grams. The specific 

 gravity of steel, if I remember rightly, is 

 somewhere about 8 ; that is, a piece of 

 steel weighs about 8 times its own volume 

 of water. Eight times I is 8. This piece 

 of steel then weighs about 8 grams. 



Now this happens to be a very simple 

 case ; but the process would give you the 

 weight in grams, whatever the dimension 

 of your piece of steel might be. If its 

 volume should be one million cubic centi- 

 meters its weight would be eight million 

 grams ; that is, if I have correctly ex- 

 pressed the specific gravity by 8. If you 

 wish to express this weight in kilograms, 

 simply shift the decimal point three 

 places to the left. A weight of 8,000,000 

 grams is equivalent to 8,000 kilograms. 



The Chairman: The unit of length is 

 what? 



Mr Bell: One meter. A centimeter is 

 one-hundredth part of that. 



The Chairman: And that is equal to 

 one liter, which filled with water is one 

 kilogram, the unit of weight? 



Mr Bell: The gram is the unit of 

 weight ; and one cubic centimeter of 

 water weighs one gram. The liter is the 

 unit of volume. It is equivalent to a 

 cubical space 10 centimeters long, 10 

 centimeters wide, and 10 centimeters 

 deep. It therefore holds 1,000 cubic 

 centimeters of space; and if filled with 

 water, the water would weigh 1,000 

 grams (or 1 kilogram). 



The fact that one liter of water weighs 

 one kilogram is easily remembered; but 

 if forgotten the knowledge is readily re- 

 covered from the basal fact that one cubic 

 centimeter of water weighs one gram 

 (the unit of weight). 



THE NEW NAMES SIMPEE WHEN UNDER- 

 STOOD 



To an American the metric system ap- 

 pears at first sight to be much more diffi- 

 cult of acquirement than it really is, on 

 account of the un-English appearance of 

 the terminology. After you have once 

 mastered the meaning of the prefixes em- 

 ployed, the whole terminology appears to 

 be beautifully simple and appropriate, the 

 words expressing by their etymology the 

 numerical relation to the units of the sys- 

 tem. 



Thus when we know that deka means 

 ten, hecto one hundred, and kilo one 

 thousand, we see at once that a deka- 

 meter means 10 meters, hectometer 100 

 meters, kilometer 1,000 meters. So with 

 the multiples of gram: A- dekagram 

 means 10 grams, hectogram 100 grams, 

 and kilogram 1,000 grams. So also, when 

 we know that deci means one-tenth, centi 

 one-hundredth, and milli one-thousandth, 

 we see at once that decimeter means one- 

 tenth of a meter, centimeter one-hun- 

 dredth of a meter, and millimeter one- 

 thousandth of a meter. In a similar man- 

 ner when we examine the subdivisions of 

 gram we see that a decigram means one- 

 tenth of a gram, centigram one-hun- 

 dredth of a gram, milligram one-thou- 

 sandth of a gram, etc. 



The foreign words employed need be 

 no bar to the use of the metric system, 



