THE YARD, PENDULUM, AND MET'RE. 447 



under line three places to the right and subtracting), and 

 the thing is done, and vice versa* Suppose now the 

 same length stated in French metres, and we would 

 ascertain what decimal fraction it is of a quadrant of the 

 French meridian. The number of metres assigned must 

 be divided by 8194 either by a long division sum or by 

 the use of a table, before the proper number to be sub- 

 tracted can be found. Which then is the shorter pro- 

 cess? and which, both scientifically and practically, the 

 preferable unit? 



(30.) If we are to legislate at all on the subject then, 

 the enactment ought to be to increase our present stand- 

 ard 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 im- 

 aginable. The change, so far as relates to any practi- 

 cal 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 milk 

 in measure or in coin would create the smallest difficulty. 

 Neither could it be doubted that our example would be 



* Strictly speaking for the conversion and reconversion we should 

 .subtract one 999th and add one loooth. But the difference is only 

 one part in a million which can never be of the slightest importance. 

 Per contra the conversion of the metre according to the process here 

 stated leads to a result which, though exact in parts of the French 

 meridian, is erroneous in parts ol the mean terrestrial meridian by 

 & considerably larger proportional part, and this is what we really 

 want to know. 



