f40 THE YARD, PENDULUM, AND METRE. 



of its meridian) that to raise an objection against the 

 practical reception of the metre, either perse, or as a sub- 

 stitute for the yard, on this score, would savour of hyper- 

 criticism. A more serious objection is the choice made 

 of the circumference of the meridional or generating 

 ellipse of the terrestrial spheroid in preference to its 

 axis of revolution. This is a blemish on the very face 

 of the system a sin against geometrical simplicity. 

 Still, were the length of the metre as determined by the 

 French geometers rigorously exact, or correct within 

 limits which the much more extensive measurements of 

 meridian arcs since made elsewhere than in France have 

 proved to be attainable, this would be only a matter of re- 

 gret, and could hardly, of itself, be drawn into an argument 

 for its rejection. But this is far from being really the 

 case. The metre, as represented by the material stand- 

 ard adopted as its representative, is too short by a 

 sensible and measurable quantity, though one which 

 certainly might be easily corrected. To show this it 

 will be necessary to enter into some detail. 



(22.) In effect, that standard is declared, in the An- 

 nuary of the Bureau des Longitudes, to be equal to 

 39-37079 British imperial standard inches. The quad- 

 rant of the French meridian then ought, if this be correct, 

 to be 393,707,900 such inches, or 32,808,992 feet. And 

 by whatever aliquot part of its whole length the true 

 quadrant exceeds this, by that same aliquot of its length 

 is the metre, so stated, erroneous. 



(23.) Mr Airy, by a combination of the whole series of 

 meridian arcs whose measures had been obtained in 



