Our System of Weights and Measures 



161 



You will probably require paper and pen- 

 cil to perform the computation; but on 

 the metrical plan the solution is so easy 

 that any intelligent person can arrive at 

 the result mentally without any calcula- 

 tion whatever. 123,456 square centi- 

 meters is equivalent to 12.3456 square 

 meters. 



Even should we forget that there are 

 10,000 square centimeters in a square 

 meter, a moment's thought will enable us 

 to recover the knowledge. The merest 

 tyro knows that a meter consists of 100 

 centimeters (the name "centimeter" itself 

 meaning "one-hundredth of a meter"), 

 so that a square meter is a surface meas- 

 uring 100 centimeters one way by 100 

 centimeters the other. 100 times 100 is 

 10,000, the figure I followed by four 

 ciphers, which means that we must shift 

 the decimal point four places to the left 

 to ascertain the number of square meters. 



HOW MUCH WATER IN THE) RESERVOIR 



Now try cubical measure ; take any 

 problem that comes to the mind. Sup- 

 pose we have a rectangular tank or reser- 

 voir of a certain length, width, and 

 depth — how much water will it hold, and 

 how much will the water weigh? 



We begin of course by multiplying to- 

 gether the length, width, and depth to 

 ascertain the cubical contents. This kind 

 of calculation must be performed, what- 

 ever the system of measurement em- 

 ployed, and I shall simply say that the 

 computation is much simpler on the met- 

 rical plan than on the other because no 

 non-decimal fractions are involved. If 

 the length, breadth, and depth be ex- 

 pressed by an exact number of feet, the 

 labor involved in this portion of the cal- 

 culation will be the same in both cases ; 

 but as a general rule in such computations 

 one or more of the dimensions will not 

 be exact in feet, but may be four feet 

 "and a half," or 3 feet "4 inches," etc., 

 and we then find it advisable to reduce 

 the whole to the lowest denomination 

 used — sav cubic inches. In such a case the 



metrical system has greatly the advan- 

 tage. But after the whole computation is 

 over and we have ascertained the cubical 

 contents in the lowest denominations em- 

 ployed, the problem is solved if the 

 metrical system is used, whereas much 

 labor is required on the present system to 

 put the answer into final shape. 



A LABOR-SAVING DEVICE 



We shall take a specific case, and in 

 order to show the ease with which the 

 problem can be mentally solved on the 

 metric system with the very largest 

 figures, we will take a sum involving nine 

 figures, thus running up into the millions. 

 Having measured our tank or reservoir 

 and performed our initial calculation, 

 suppose we find that the tank contains 

 123,456,789 cubic inches of water. 



How many gallons have we there ? And 

 how much does the water weigh? 



I will not attempt to work the result 

 out to its final conclusion even with the 

 aid of paper and pencil, for I must con- 

 fess that my memory does not hold the 

 exact number of cubic inches contained in 

 a gallon and I have no means of recover- 

 ing this knowledge excepting by refer- 

 ence to a printed table. Then again my 

 memory does not retain a distinct impres- 

 sion of the relation of weight to volume 

 of water on our present system. The 

 problem is therefore absolutely insoluble 

 to me at the present moment. I must 

 consult some reference book for the in- 

 formation that would enable me to work 

 it out. But put the problem in metrical 

 terms and the problem is solved as soon 

 as you have ascertained the cubical con- 

 tents in any of the metrical denomina- 

 tions you prefer; the translation of the 

 result into other more convenient de- 

 nominations of the metrical system re- 

 quires no calculation and is a mere ques- 

 tion of putting the decimal point in the 

 proper place. 



For example, suppose we find that our 

 tank hold 123,456,789 cubic centimeters 

 of water. How many liters have we 



