XIV.] UNITS AND STANDARDS OF MEASUREMENT. 329 



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

 niininjf the mechanical equivalent of heat. There is a 

 morality brought to bear upon such matters which, in 

 point of severity, is probably w^ithout 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 | (n^ — n) 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 wliich the 

 lines of inference from one phenomenon to another I'apidly 

 grow in complexity, and the powers of scientific prediction 

 are correspondingly augmented. 



Eabbage 1 proposed the formation of a collection of the 

 constant numbers of nature, a work wliich has at last 

 been taken in hand by the Smithsonian Institution.'^ 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, Ilutton's, and many 

 other tables of logarithms, and a somewhat larger collec- 

 tion is given in Templeton's MUlu-riylU and Engineers 

 Pocket Comijanion. 



Our present object will be to classify these constant 

 numbers roughly, according to their comparative generality 

 and importance, under the following heads : — 

 (i) jSIathenuitical constants. 



(2) Physical constants. 



(3) Astronomical constants. 



(4) Terrestrial numbers. 



(5) Organic numbers. 



(6) Social numbers. 



' British Agsociation, Cambridge, 1833. Report, \m. 484—490. 



2 Smithsonian Miscellaneons Colkctiona, vol. xii., the Constants of 

 Nature, part. i. SpeciHc gravities compiled by ¥. W. Clarke. 8v<x 

 Wa.shinglon, 1873. 



