446 THE YARD, PENDULUM. AND METRE. 



from our side. (I say nothing at present of decimaliza- 

 tion). 



(29.) Let us see then how this part of the matter stands. 

 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 metrical 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 differs only by 2944 inches, or by 82 yards 

 from 500,500,000 (five hundred million and five hundred 

 thousand) such inches and this would be the whole error 

 on a length of 8000 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 funda- 

 mental unit of length. Suppose, then, that any length 

 were proposed in English measure, and we desire to 

 know what decimal fraction such length were of the 

 earth's axis. We have only to express it in inches and 

 decimals, and from the number so stated take off its 

 thousandth part (a calculation involving only the writing 

 down the number twice over, removing the figures of the 



* A writer in Quesnevilles Moniteur Scientifiqtie, No. 163, v. 736, 

 argues that itinerary measures ought to be based on the circumfer- 

 ence of the globe and not on its axis by reason that the decimal 

 principle of sub-division, if carried out, would apply to the decimal 

 graduation of the quadrant adding that "the greatest advantage 

 of the French system is in reality its decimal division" but for- 

 getting- to add that the decimal division of the quadrant was intro- 

 duced in France, but was abandoned by common constnt even in 

 France, and can never be reintroduced. In the " Mondes" (SuppL 

 38, p. 6 1 6) the same argument is advanced, and the same answer 

 applies. 



