i86 POPULAR SCIENCE MONTHLY. 



THE METRIC SYSTEM.* 



Bt heebeet spencee. . 



{With a Letter from Sir Frederick Bramwell.) 



A DVOCATES of the metric system allege that all opposition 

 -'LJL- to it results from " ignorant prejudice." This is far from 

 being the fact. There are strong grounds for rational opposition, 

 special and general ; some already assigned and others which re- 

 main to be assigned. I may fitly put first a carefully-reasoned 

 expression of dissent from a late man of science of high authority. 



In 1863 Sir John Herschel published an essay, in which, after 

 referring to an attempt made during the preceding session to 

 carry through Parliament a bill establishing the French metrical 

 system in this country, and anticipating that the bill (said to 

 have been confirmed in principle) would be again brought for- 

 ward, he proceeded to contrast that system with a better one to 

 be reached by making a minute modification in our own unit of 

 measure. The following extract will sufficiently indicate the line 

 of his argument : — 



Let us now see how far the French metre as it stands fulfills the re- 

 quirements of scientific and ideal perfection. It professes to be the 

 10,000,000th part of the quadrant of the meridian passing through France 

 from Dunkirk to Formentera, and is, therefore, scientifically speaking, a 

 local and national and not a universal measure. . . . The metre, as rep- 

 resented by the material standard adopted as its representative, is too short 

 by a sensible and measurable quantity, though one which certainly might 

 be easily corrected. 



[In the appendix it is shown that according to the latest measurements 

 the error is 1-1 63d part of an inch on the metre.] 



Sir John goes on to say that " were the question an open one 

 what standard a new nation, unprovided with one and unfettered 

 by usages of any sort, should select, there could be no hesitation 

 as to its adoption (with that very slight correction above pointed 

 out) " ; and he then continues — 



The question now arising is quite another thing, viz. : — Whether we are 

 to throw overboard an existing, established, and, so to speak, ingrained sys- 

 tem — adopt the metre as it stands for our standard — adopt, moreover, its 

 decimal subdivisions, and carry out the change into all its train of conse- 

 quences, to the rejection of our entire system of weights, measures, and 

 coins. If we adopt the metre we can not stop short of this. It would be a 



* Most of the matter in this article appeared originally in the form of unsigned letters 

 n the London Times. The interest in the subject in the United States warrants its repub- 

 ication in the Monthly, with a view to which Mr. Spencer has kindly consented to allow his 

 authorship of the letters to be made known. 



