150 



SCIENCE. 



[N. S. Vol. I. No. 6. 



subjects. His memoirs ( of which there 

 are more than 150) must even now be 

 classed amongst the best models of scientific 

 exposition. 



It is a striking series of facts that the three 

 most eminent workers in our science during 

 the period in question, a period extending, 

 say, from 1775 to 1825, were all Frenchmen, 

 that they were warm personal friends, and 

 that they all resided, in their later years at 

 least, at Paris. Still more striking is the 

 fact that this period of extraordinary devel- 

 opment in mechanical science was coinci- 

 dent with a period of most profound social 

 agitation with Frenchmen in general and 

 with Parisians in particular. How was it 

 possible to pursue abstract theories of matter 

 and motion, how was it possible to con- 

 template the grandeur of the celestial uni- 

 verse at a time when the heads of states- 

 men and philosophers were falling into the 

 waste basket, not before the metaphorical 

 axe of changing ministers, but before the 

 whetted blade of the guillotine ? Tocque- 

 ville, in his Democracy in America, has 

 warned us against the depressing effect on 

 abstract thought of the incessant attrition 

 of American life. Why did not the stormy 

 times of the French Kevolution check the 

 cui'rent of scientific progress ? The answer 

 to these questions is to be found, I think, 

 in the fortunate circumstance that French- 

 men and the French government, whatever 

 may have been their shortcomings in other 

 respects, have developed a higher apprecia- 

 tion for science and scientific men than any 

 other nationality. However they may have 

 fallen out as a people on questions of religion 

 and politics, they have maintained a high 

 regard for scientific thought. It was his 

 admirable devotion to celestial mechanics 

 that saved Laplace from disgrace, or a worse 

 fate, at the hands of his fellow-countrymen. 

 Even the sorry figure he cut during his brief 

 career as Minister of the Interior, into the 

 business of which he introduced the ' spirit 



of the infinitesimals,' as the future emperor 

 said, did not deprive him of favors due to a 

 man of science. 



The personal characteristics and the inti- 

 mate friendship and association of Lagrange, 

 Laplace, and Poisson are amongst the most 

 attractive features of their lives, and worthy 

 of a brief digression. 



Lagi-ange was of French descent, though 

 he was born at Turin and became famous 

 before taking up a residence at the focus of 

 French civilization. While yet a youth, 

 the ample means of his family were lost in 

 commercial speculation; and to this early 

 lesson of adversitj' is due, probably, the de- 

 termination of his career, for he was wont 

 to say that had he been rich he might never 

 have pursued mathematical studies. Like 

 most mathematicians of distinction, he 

 seems to have owed much less to scholastic 

 instruction than to his own efforts and in- 

 dustrjr. At the age of eighteen he was ap- 

 pointed professor of mathematics at the 

 royal school of artillerj^ at Turin; and at 

 nineteen he was in correspondence with 

 Euler concerning isoperimetrical problems, 

 which ultimatelj^ led to his perfection of that 

 highest branch of pure mathematics, the 

 caculus of variations. At twenty-two he 

 was one of the founders of a society which 

 afterwards became famous as the Turin 

 Academy of Sciences. At the early age of 

 thirtj' he was called to the post of director 

 of the mathematical department of the Ber- 

 lin Academy of Sciences as the successor of 

 the distinguished Euler. Here he remained 

 for twenty years' working with marvelous 

 industry and success. About the time of 

 the appearance of his great work on analy- 

 tical mechanics in 1788, he removed to Paris 

 at the instance of the French court, which 

 made him a ' veteran pensioner ' and re- 

 ceived him with the most flattering honors. 

 He lived throxigh the stormy period of the 

 Revolution, winning additional favoi-s and 

 distinctions fi-om the French government, 



