May 15, 1896.] 



SCIENCE. 



745 



in scientific reasoning in spite of the Newtonian 

 definition of motion and the definitions given to 

 momentum, energy, force and power. Curious- 

 ly, I find that even some physicists have not 

 mastered these definitions and still entertain 

 the historical illusion concerning the nature of 

 rest. If my demonstration is studied it will be 

 accepted only in case it does not conflict with 

 some other notion, as that about the nature of 

 relation. 



Finally, let me present three other proposi- 

 tions: First, to produce rest in one body it is 

 necessary to transmute one mode of motion 

 into another; second, to produce a new mode of 

 motion it is necessary to transmute a part or 

 the whole of some other mode of motion. Both 

 of these definitions are included in the axiom 

 which I have previously given, that motion 

 cannot be created or destroyed. Third, if mo- 

 tion is not both absolute and relative it does 

 not exist. J. W. Powell. 



SCIENTIFIC LITER ATUBE. 

 Life, Letters and Works of Louis Agassiz. By 



Jules Maecou. With Illustrations. Two 



volumes. New York, Macmillan& Co. 1896. 



Pp. 302, 318. 



Mrs. Agassiz's life of her illustrious husband 

 has always been considered a model of what 

 such a biography should be, full and minute 

 where the matters were important, brief where 

 they were trivial, and composed by elimination 

 rather than agglomeration, so that the e£Fect is 

 massive and interesting from first to last. Mr. 

 Marcou seems to have aimed at muchness of 

 matter rather than excellence of form, and the 

 result is a very different sort of book, realistic 

 and abounding in traits vifs, but pervaded by a 

 curious commonness of tone, and by a lack of 

 style rather odd in a Frenchman. In his eager- 

 ness to supply every detail of date, place, per- 

 sons present etc., where events are recounted, 

 too many pages are filled with mere statistical 

 enumeration. 



Too much is said of individuals who play 

 subordinate parts in the narrative, and who 

 ought either to have been subordinated still 

 more or made more interesting by becoming 

 more prominent. Any attempt on the part of 

 an outsider to give an in-door view, a view en 



robe de cliambre, so to speak, of a man whose 

 family is still living, savors of a certain had taste, 

 and the strained air of familiarity on Mr. Mar- 

 cou's part ends by displeasing the reader the 

 more, as it frequently appears to be an appear- 

 ance of knowingness rather than a real knowl- 

 edge, where minor events and personages are 

 considered. 



It offends most in the author's handling of 

 certain persons who, having once been co- 

 workers with Agassiz, had in one way or an- 

 other ceased to be his friends. Human nature, 

 even when in the wrong, demands something 

 more than this off-hand contemptuous treat- 

 ment, or else something less in the way of 

 space taken up. The book, moreover, is written 

 most disjointedly, is full of repetitions, and its 

 comments on Agassiz's zoological philosophy 

 are sadly beneath the level of the subject. But 

 in spite of these defects — and they are truly 

 grave ones — Mr. Marcou has evidently taken 

 great pains with his volumes, and has achieved 

 a result which probably comes quite near that 

 at which he aims. In spite of his non-idealiz- 

 ing temperament, he genuinely admires his 

 hero; and what with his facts, his broader ap- 

 preciations, and all his little dabs and touches, 

 the reader gets at last a picture of Agassiz 

 which is both vivid and realistic, and awakens 

 sympathetic admiration far more than any 

 other kind of comment. Agassiz's personality 

 was indeed so immense, his passions so over- 

 powering, his enthusiasms so magnificent, his 

 sociability and friendliness so great, that no 

 other result was possible. His life, in all its 

 phases, becomes inevitably a sort of heroic 

 romance. Never was there so glorious a youth. 

 At 20 he was a great collecting naturalist. At 

 22, whilst a student at Munich, he had pub- 

 lished his folio describing Spix's collection of 

 Brazilian fishes. At 23 he had begun work on 

 his Sistoire Naturelle des Poissons. At 26 his 

 Becherches siir les Poissons fossiles began to ap- 

 pear. At 30 he had proved the ' Glacial Epoch ' 

 and received the Wollaston medal from the 

 Geological Society — a unique honor for so 

 young a man. Mr. Marcou catalogues 43 pub- 

 lications from his pen, many of them of the 

 first order of magnitude, before his 31st year. 

 And all this with no basis of support but his 



