Makch 8, 1895.] 



SCIENCE. 



269 



Mr. Lawrence was one of the most care- 

 ful and prolific of American oruithologists. 

 The list of his published \\Titings * contains 

 r_'l titles, the earliest of which appeared in 

 1844, the latest in ISill. The period of 

 his productive activity thus covered nearly 

 half a century. He was an active contem- 

 porary of all American ornithologists from 

 Audubon and Xuttall to the younger writ- 

 ers of the present day. ' Baird, Cassin and 

 . LiiwTcnce ' ai-e classic names in ornithology 

 — names associated in joint authorship in 

 Biiird's gi-eat work on the birds of North 

 America, published in 1858. For nearly 

 fifty j-ears Baird and Lawi'ence, then the 

 foremost authorities on jAmerican birds, 

 were waim personal friends, and on more 

 than one occasion accomplished, by hearty 

 cooperation, what neither could have done 

 alone. It should not be forgotten that their 

 arduous labors paved the way for the re- 

 finement of detail that characterizes the 

 bird work of to-day. 



Baird busied himself chiefly with the 

 birds of the Vnited States, Lawrence chieflj- 

 with those of tropical America. LawTence 

 described more than .'JUO new species from 

 the West Indies, Mexico, Central and South 

 America. One genus and twenty species 

 were named in his honor — tokens of respect 

 and esteem — by American and European 

 naturalists. 



Baird and Lawrence lived under widely 

 diflerent conditions. Baird led an active 

 official life, burdened with the cares and 

 responsiljilities of three great institutions, 

 two of which, the National Museum and 

 Fish Commission, were his own creation ; 

 he was constantlj' overworked and died 

 prematurely at the age of sixty-five years. 

 Lawrence led a quiet, retiring life, far away 

 from the public eye, and died at the ripe 

 age of fourscore years and nine. Still, the 



*The Published Writiiif.'sof George Newliold Liiw- 

 reiice, by L. S. Foster. Hull. U. S. National Musemn, 

 No. 40. 1892. 



two had many traits in common ; both were 

 plain and unassuming, kind and thoughtful 

 in their family relations, and ever ready to 

 extend a helping hand to those, however 

 young, whose tastes led them to tlie study 

 of birds. In looking l)ack over the twenty- 

 five years that have passed since I first 

 enjoyed their acquaintance, my mind con- 

 stantly recurs to the kindly words of en- 

 couragement and advice that shaped my 

 early course as a naturalist, and the friend- 

 shijjs that followed will always live among 

 my most cherished memories. 



C. Hart Merriam. 



SCIENTIFIC LITERATURE. 

 A Ti-eatUe on Hydrostatic. By Alfred 

 George Greenhill, Professor of Mathe- 

 matics in the Artillerj' College, AVool- 

 wich. Macmillau & Co., London and 

 New York. 16mo, pp. viii-|-53t5. 

 The science of hydrostatics, originating 

 -with Archimedes, is now more than twentj' 

 centuries old. It is, in many respects, one 

 of the most perfect and satisfactorj' of the 

 sciences. This fact, however, arises from 

 the simplicity of the phenomena with which 

 hydrostatics has to deal rather than from 

 anj'thing like continuity of progress during 

 its lengthy history. Indeed, as regards 

 purely hydrostatical priuciples, we are not 

 very greatly in advance of Archimedes. 

 Our superiority over him is due, first, to an 

 immensely enlarged capacity, through the 

 developments of mathematics, for the aj)- 

 plication of those principles; and, secondly, 

 to the e.xjjloration of the much larger and 

 more interesting domain of hydrodynamics, 

 of which, in fact, hydrostatics is only a 

 special case. 



The work of Professor Greenhill treats 

 hydrostatics from the modern point of view. 

 He does not hesitate to cross the border for 

 an excursion into hydrokinetics whenever 

 desirable or essential, although some might 



