THE METRIC SYSTEM. 187 



standing reproach and anomaly — a change for changing's sake. The 

 change, if we make it, must be complete and thorough. And this is in the 

 face of the fact that England is beyond all question the nation whose com 

 mercial relations, both internal and external, are the greatest in the world, 

 and that the British system of measures is received and used, not only 

 throughout the whole British Empire (for the Indian '"Hath" or revenue 

 standard is defined by law to be 18 British imperial inches), but throughout 

 the whole North American continent, and (so far as the measure of length 

 is concerned) also throughout the Russian Empire. . . . Taking commerce, 

 population, and area of soil then into account, there would seem to be far 

 better reason for our Continental neighbors to conform to our linear unit 

 could it advance the same or a better a priori claim than for the move to 

 come from our side. (I say nothing at present of decimalization.) 



Sir John Herschel then argues that the 10,000,000th part of 

 the quadrant of a meridian, which is the specified length of the 

 metre, is, on the face of it, not a good unit of measure, inasmuch 

 as it refers to a natural dimension not of the simplest kind, and 

 he continues thus : — 



Taking the polar axis of the earth as the best unit of dimension which 

 the terrestrial spheroid affords (a better a priori unit than that of the met- 

 rical system), we have seen that it consists of 41,708,088 imperial feet 

 which, reduced to inches, is 500,497,056 imperial inches. Now, this diffei*s 

 only by 2,944 inches, or by 82 yards, from 500,500,000 such inches, and 

 this would be the whole error on a length of 8,000 miles which would 

 arise from the adoption of this precise round number of inches for its 

 length, or from making the inch, so defined, our fundamental unit of 

 length. 



After pointing out that the calculation required for correlat- 

 ing a dimension so stated with the earth's axis is a shorter one 

 than that required for correlating such dimension with the quad- 

 rant of a meridian. Sir John Herschel argues that — 



If we are to legislate at all on the subject, then the enactment ought to 

 be to increase our present standard yard (and, of course, all its multiples and 

 submultiples) by one precise thousandth part of their present lengths, and 

 we should then be in possession of a system of linear measure the purest 

 and most ideally perfect imaginable. The change, so far as relates to any 

 practical transaction, commercial, engineering, or architectural, would be 

 absolutely unfelt, as there is no contract for work even on the largest scale, 

 and no question of ordinary mercantile profit or loss, in which one per 

 mille in measure or in coin would create the smallest difficulty. 



Hitherto I have said nothing about our Aveights and measures of ca- 

 pacity. Now, as they stand at present, nothing can be more clumsy and 

 awkward than the numerical connection between these and our unit of 

 length. 



And then, after pointing out the way in which the slight modi- 

 fication of the unit of linear measure described by him could be 

 readily brought into such relation with the measures of capacity 

 and weight as to regularize them, he goes on : — 



And thus the change which would place our system of linear measure 



