xiv.] UNITS AND STANDARDS OF MEASUREMENT. 329 



mining coefficients of expansion ; or by a Joule in deter- 

 mining the mechanical equivalent of heat. There is a 

 morality brought to bear upon such matters which, in 

 point of severity, is probably without a parallel in any other 

 domain of intellectual action." 



Every new natural constant which is recorded brings 

 many fresh inferences within our power. For if n be the 

 number of such constants known, then \ (ri 2 11) is the 

 number of ratios which are within our powers of calcula- 

 tion, and this increases with the square of n. We thus 

 gradually piece together a map of nature, in which the 

 lines of inference from one phenomenon to another rapidly 

 grow in complexity, and the powers of scientific prediction 

 are correspondingly augmented. 



Babbage l proposed the formation of a collection of the 

 constant numbers of nature, a work which has at last 

 been taken in hand by the Smithsonian Institution. 2 It 

 is true that a complete collection of such numbers would 

 be almost co-extensive with scientific literature, since 

 almost all the numbers occurring in works on chemistry, 

 mineralogy, physics, astronomy, &c., would have to be 

 included. Still a handy volume giving all the more 

 important numbers and their logarithms, referred when 

 requisite to the different units in common use, would be 

 very useful. A small collection of constant numbers will 

 be found at the end of Babbage's, Button's, and many 

 other tables of logarithms, and a somewhat larger collec- 

 tion is given in Templeton's Millwright and Engineers 

 Pocket Companion. 



Our present object will be to classify these constant 

 numbers roughly, according to their comparative generality 

 and importance, under the following heads : 



(1) Mathematical constants. 



(2) Physical constants. 



(3) Astronomical constants. 



(4) Terrestrial numbers. 



(5) Organic numbers. 



(6) Social numbers. 



1 British Association, Cambridge, 1833. Report, pp. 484490. 



2 Smithsonian Miscellaneous Collections, vol. xii., the Constants of 

 Nature, part. i. Specific gravities compiled by F. W. Clarke. 8vo. 

 Washington, 1873. 



