144 



SCIENCE. 



[N. S. Vol. XIV. No. 343. 



metrological reform has been unprecedentedly 

 great and there is a general conviction that 

 abandonment of the antiquated, inconvenient 

 and unscientific systems of measure now in use 

 must soon become an absolute necessity. 



Under these conditions the excellent treatise 

 of M. Bigourdan is a most timely and welcome 

 contribution to available literature relating to 

 the history of the origin and the gradual prop- 

 agation of the metric system of weights and 

 measures. In its preparation the author has had 

 the advantage of convenient reference to orig- 

 inal papers, state, scientific and personal, and in 

 his resume of the very important operations of 

 the last quarter of a century, as embodied in the 

 work of the International Bureau of Weights 

 and Measures, he has been able to avail himself 

 of the thorough knowledge of Messrs. Benoit 

 and Guillaume, the two distinguished experts 

 of that bureau. 



The book begins with a brief discussion of 

 the chaotic state of all matters relating to 

 standards of measure during a few centuries 

 preceding the coming of the metric system, in 

 which little is said of anything outside of 

 France. At a very early period in the history 

 of metrologj' attempts were made to establish 

 natural standards — that is, to refer ordinary 

 standards of measure to something in nature 

 fixed and unchangeable. It was not until 1670, 

 however, that a really rational and scientific 

 scheme was proposed by Gabriel Mouton, vicar 

 of the Church of St. Paul in Lyons. 



A few years earlier than this it had been pro- 

 posed to refer the standard of length to the 

 pendulum making a single vibration in one 

 second or in some fraction of a second. Per- 

 haps this suggestion came first from Sir Chris- 

 topher Wrenn, and it was made about 1670-73 

 by Picard and by Huyghens. Mouton' s system 

 was in principle the metric system of to-day ; 

 he proposed to refer the standard of length to 

 an arc of the terrestrial meridian ; his multi- 

 ples and submultiples of the unit were decimal, 

 and he also proposed for convenience of repro- 

 duction a reference to the seconds pendulum. 

 It is interesting to note that when Picard pro- 

 posed the seconds pendulum as a standard of 

 length in 1671, he expressed a suspicion that 

 such a pencjulum must be somewhat shorter 



near the equator than near the pole, although 

 it was only in that same year that Eicher went 

 to South America to make a series of astro- 

 nomical observations, during which this fact 

 was actually proved. 



During the next hundred years many sugges- 

 tions looking to a reformation of standards were 

 made in France and many projects drawn up to 

 bring about a unification of weights and meas- 

 ures throughout the nation, but it was not until 

 one was presented by Talleyrand, about 1789, 

 that the real movement set in. In this project 

 he advocates the use of the pendulum as a 

 standard of length, and with evident apprecia- 

 tion of the importance of the matter with which 

 he is dealing, he suggests a reference of the 

 subject to a joint international commission, to be 

 composed of an equal number of members of 

 the French Academy of Sciences and of Fellows 

 of the Royal Society of London. At about the 

 same time an active agitation in favor of metro- 

 logical reform began in England and also in the 

 United States, its chief exponent in our own 

 country being Thomas Jefferson. Unhappily 

 neither of these movements came to much, for 

 reasons that cannot here be gone into. The 

 history of the creation of the metric system and 

 its adoption by the French Government, which 

 followed within a few years after Talleyrand's 

 project was submitted, is pretty well known to 

 those interested in this phase of the subject, and 

 the details of it constitute the larger part of the 

 volume under review. 



The whole subject was in the beginning re- 

 ferred to a Commission which, with those that 

 were subsequently appointed, fortunately in- 

 cluded such men as Laplace, Lagrange, Borda, 

 Mong6, Condorcet, Lavoisier, Delambre, Coul- 

 omb, Cassini and others, constituting a most 

 brilliant array of Frenchmen most eminent in 

 science. 



Consideration was given to three ' natural ' 

 standards to which the unit of length might be 

 referred : The length of a pendulum beating 

 seconds, the quarter of the terrestrial equator 

 and the quarter of the terrestrial meridian. 

 The pendulum was rejected, principally because 

 its use involved the elements time and force, 

 both foreign to length; the equator was rejected 

 because of the difficulty of measuring it, climatic 



