THE YARD, PENDULUM, AND METRE. 423 



arising as to the length of any object stated to contain 

 a given number of such units or its aliquots. A very 

 moderate experience would however suffice to convince 

 anybody that among natural objects of the same kind, 

 even those most common, perfect identity of length, of 

 breadth, of thickness, any more than of weight, is never 

 observed even a close approach to it rarely and a 

 very close one extremely so. Still, with all drawbacks 

 so arising on the adoption of a natural standard, the first 

 rude demand for such a standard would be easily enough 

 satisfied, and that in two ways, viz. : ist, by actually 

 fixing upon some individual among all the existing ob- 

 jects of the sort selected, to the exclusion of others or, 

 2dly, by the very natural, though somewhat more re- 

 fined conception of an ideal medium, or mean among a 

 very great multitude of such objects, such as might be 

 regarded as neither unusually great nor unusually little 

 ones of their kind. 



(4.) Among objects of common occurrence, the 

 human person, or some distinct member of it would be 

 most likely to claim the attention of mankind as afford- 

 ing a standard of measure ; if only for the very obvious 

 reason that the relation of the sizes of material objects 

 to that of man mainly determines his facility of hand- 

 ling, or otherwise applying them to human uses. Ac- 

 cordingly, the height of a full grown person, the length 

 of his arm, his fore-arm (ulna or ell), his foot, his 

 hand, his ordinary step, &c., would present, and is well 

 known to have presented itself among almost all com- 

 munities of mankind to their choice for this purpose. 



