3 2 4 POPULAR SCIENCE MONTHLY. 



cf labor in school could be saved to the scholars of all the U. S. public 

 schools, by the substitution of the metric system for the existing sys- 

 tem. This saving would enable the scholars to learn more in other 

 directions during the time saved. Nevertheless, it is sometimes gravely 

 asserted that the value of the present system is the difficulty it provides 

 for exchange, and estimates, and computations of all kinds, thus afford- 

 ing useful mental exercise, both for school children and for adults. 

 Fears are occasionally expressed that the substitution of the metric sys- 

 tem would make mental arithmetic in such matters so easy that the 

 aptitude would be lost. According to this argument, we should make 

 all mental operations as hard as possible, artificially. 



So complex is our customary system of weights and measures, that 

 there are comparatively few persons who can recite from memory all 

 the various tables taught in our schools. So ambiguous is the system, 

 that many cultured persons are not aware of the difference between 

 British and U. S. gallons, quarts, pints, bushels, pecks, etc. Some 

 cultured persons are even unaware of the difference between the 

 apothecary's ounce or pound and the avoirdupois ounce or pound. 



The argument is often made that the English-speaking people 

 should adhere, for patriotic reasons, to their national standards as 

 against standards of French creation. Surely the answer to such a 

 plea is that the question is not between the English and the French 

 peoples, but between the English-speaking peoples and the rest of the 

 civilized world. The metric system is the only system of weights and 

 measures that can be called international. Moreover, only the very 

 best available system should be good enough for Americans. 



It is sometimes complained that the meter as a unit should be set 

 aside because it is inaccurate. In order to make the standard length 

 international, France decided upon a decimal fraction (the ten mill- 

 ionth part) of the distance between the geographical pole and the 

 equator, measured on the Paris Meridian of the earth's surface. The 

 meter arrived at by the French geodesists at the beginning of the 

 nineteenth century appears by the most recent publications of the 

 Bureau des Longitudes to have been a little short of the mark. It 

 seems that the international meter, defined as the distance between 

 the centers of two marks on the standard meter bar kept in the Inter- 

 national Bureau of Weights and Measures at Paris, is just about one- 

 fiftieth part of 1 per cent, shorter than the ten millionth part of the 

 quadrantal arc of the earth above referred to. This small discrepancy 

 is evidently of no material consequence; partly because a discrepancy 

 ceases to be a source of error as soon as its magnitude becomes known, 

 and partly because all copies of the meter are made by bar-to-bar com- 

 parison and not from comparison with the dimension of the earth, 



