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a powerful impetus to the study of the natural sciences at the 

 close of the last century. For their authors, with great abilitj' and 

 with much logical acumen and fulness of illustration, maintained 

 most peremptorily, as Locke had done more than a century before, 

 that all our knowledge is really due to the study of the external 

 world. Under the influence of the leading principle thus forcibly 

 inculcated, some of the ablest intellects of France began to devote 

 themselves, with extraordinary activity, to the study of the phe- 

 nomena of nature. The laws of the radiation and conduction of 

 heat were worked out by Prevost and Fourier ; electrical phe- 

 nomena were investigated by D'Alibard and Coulomb, while 

 Mains and Fresnel, bj r their researches upon double refraction 

 and the polarization of light, extended the bounds of our knowl- 

 edge of optics. At the same time Lavoisier, by investigating with 

 great ability the laws of oxidation, placed chemistry upon a 

 strictly scientific basis, and, in conjunction with Berthollet, De 

 Morveau, and Fourcnrv, laid down, for the first time, a systematic 

 chemical nomenclature. Meanwhile, geology was also cultivated 

 with eminent success by Buflbn, Rouelle, Desmarest, Dolomieu 

 and Montlosier; while astronomy, both ph} T sical and mathemati- 

 cal, was materially advanced by La Grange's discovery of the 

 periodical inequalities of the planets, and by the publication of 

 the " Mechanique Celeste" of Laplace, in which was clearly pre- 

 sented to the world for the first time the famous " nebular hypo- 

 thesis" an lrppothesis which is steadily approaching the character 

 of a demonstration with every new discovery in astronomical 

 science, and which has not only anticipated, but has also paved 

 the way for, the co-ordinate doctrine of evolution in biology. In 

 1TG2 Paubenton gave a new interest to palseontolog}^ by apply- 

 ing, for the first time, the principles of comparative anatomy to 

 the study of fossil bones. In this epoch, also, the illustrious Cu- 

 vier gave to both geology and palceontology an eminently philoso- 

 phical character by practically associating the study of the earth's 

 strata with the fossil remains found therein. This greatest of all 

 descriptive anatomists did much for philosophical natural history 

 by showing that the classification of animals must be based upon 

 the comprehensive study of their organs rather than their ex- 

 ternal characters. Histolog}', botany, and mineralogy likewise 

 found zealous investigators during this remarkable intellectual 

 period. While Bichat witli scientific skill and industry was 



