THE METRIC SYSTEM. 725 



to quote another objector to the metric system in the person 

 of Prof. H. A. Hazen, of the United States Weather Bureau, 

 who some time ago argued that its adoption would necessarily 

 include that of the centigrade thermometer scale, and that as, in 

 his opinion, this was very bad, the metric system must be very 

 bad. Among meteorologists and physicists this reference will be 

 thought to be singularly unfortunate, and it furnishes a striking 

 illustration, among the many to be found in the article under 

 review, of Mr. Spencer's inability to recognize or properly esti- 

 mate " values " in regions of thought to which, it must be admit- 

 ted, he is comparatively a stranger. However much one might 

 doubt the conclusions reached by Sir John Herschel, his splendid 

 career as an astronomer and exponent of exact science commands 

 the respect of all lovers of real learning. When we consider that, 

 first, the centigrade thermometer scale has no more to do with 

 the metric of weights and measures than with the coinage of the 

 United States, and, second, its advantages over the unscientific 

 and awkward scale of Fahrenheit are so many and so great that it 

 is already well-nigh universally used, and almost absolutely so 

 among scientific men of all races and nations, it is apparent that 

 no time need be wasted in commenting upon a statement which, 

 by its juxtaposition with that of Herschel, has already achieved 

 a notoriety to which it has no claim either by reason of character 

 or ancestry. 



In his second letter Mr. Spencer's own arguments begin to be 

 developed. He first objects to the metric system because, although 

 it is a century old, it has not yet, even in France, entirely driven 

 out some of the old denominations and units. In reply to this it 

 may be said that little research is required to reveal innumerable 

 examples of persistence in the use of words and things for more 

 than a hundred years after their betters were available. On this 

 point I will imitate Mr. Spencer by quoting from a letter re- 

 cently received from a well-known man of science and admirer 

 of our distinguished opponent. He writes : " This is amazing 

 when coming from Spencer. He says on page 189, ' But one 

 might have thought that after three generations daily use of 

 the new system would have entailed entire disappearance of 

 the old, had it been in all respects better.' Now Spencer knows 

 better than any one else the persistency of habit in all people. 

 A volume a foot thick might be written on the persistence of 

 habit." 



The next objection is worthy of more serious consideration, 

 and it has been given (for it has long been discussed) a good deal 

 of weight by many thoughtful people. It refers to the alleged 

 universal tendency to continual bisection, thus leading to the use 

 of halves, quarters, eighths, sixteenths, thirty- seconds, sixty- 



