20 



SCIENCE. 



[X. p. Vol. I. Xo. 1. 



entomologists, but their aiitoptic acquaint- 

 ance with oiu- fauna is relatively poor ; and 

 while there are ample materials here, there 

 appears a remarkable paucity of students 

 inclined to serious work in this direction. 

 Lists we have in number, but in them al- 

 most invariably figure Acridium, Calop- 

 tenus, Oedipoda, Stenobothi-us, Mantis, etc., 

 genera which in their now resti'icted appli- 

 cation do not or hardly exist in North 

 America. 



There has been some excuse for this, since 

 the broad scope of Stal's work, embracing 

 the Orthoptera of the globe, rendered work 

 upon exclusively American material diffi- 

 cult to one without means of reference to 

 extra- American insects, collections of which 

 are uncommon in this country, though 

 easily obtainable by any one with means. 

 Still, it is sti-ange that no one having access 

 to the museums in our larger cities or uni- 

 versities has undertaken to apply the 

 modern system of classification to one or 

 another of the families or subfamilies of 

 American Orthoptera. He would have 

 earned merited applause from all students 

 ia this field. 



One attempt, indeed, was made to collate 

 what could be known of the Acrididfe, biit 

 it was before Stal began his work, and it 

 may almost be classed as a hindrance. 

 Now, however, the field is open, for Brunner 

 von Wattenwjd, whose collection of Or- 

 thoptera is the richest in the world, pub- 

 lished a year ago a Revision du Systhne des 

 Orthoptcres, through which, by means of 

 the tables given by him of an exceedingly 

 simple character (sometimes in practice one 

 finds them too limited), one may quickty 

 group his collection in a natviral order, and 

 by means of the literature to which refer- 

 ence is briefly made, determine the generic 

 position or affinities of whatever he has be- 

 fore him. The way for a revision of any 

 group is therefore clearer than ever before, 

 and oiir entomologists will have none but 



themselves to blame if they do not here- 

 after better coordinate their work wdth that 

 of the Eiu-opean writers. 



Samuel H. Scuddkr. 

 Cambeidge. 



SCIENTIFIC LITERATURE. 

 An Elementary Treatise on Theoretical Me- 

 chanics. — Part I., Kinematics ; Part 11. , In- 

 trodiietion to Dynamics; Part III., Kinetics. 

 — By Alexander Ziwet, Assistant Pro- 

 fessor of Mathematics in the University 

 of Michigan. — 8vo. — Macmillan & Co., 

 London and New York, 1893-94. Pp. 

 viii+181, vui+183, viii+236. 

 Since Lagrange set the model for analji:i- 

 cal mechanics in his Mecanique Analytique, a 

 little more than a century ago, there has 

 been no serious lack of good elementary 

 works devoted to that science. Most con- 

 spicuous of the latter is Poisson's Mecanique 

 (1811, 2d ed., 1833), which was undoubtedly 

 naore mdely read and followed than any 

 other work duiing the first half of this cen- 

 tury. It is only recently, however, that the 

 great advantage of the analj^tical over the 

 geometrical method in mechanics has come 

 to be generally recognized by authors and 

 educators. The influence of Newton has 

 long held English wi-iters to the geometrical 

 form of the Principia. To this, neverthe- 

 less, there are a few noteworthj' exceptions, 

 the most important of which in the present 

 half centiiry is probably Price, whose vol- 

 umes on analji:ical mechanics {Infinitesimal 

 Calcidus, Vols. III. and IV., 1S(J2) have 

 done excellent service. 



Along with the remai'kable growth of 

 science in general duriQg the past thirty 

 years a great impetus has been given to 

 mechanics. This is traceable chiefly to two 

 sources, namely : first, the develoj^ment of 

 the Faraday-Maxwell view of electricity 

 and magnetism ; and, second, the thought- 

 inspiring qualities of the great work of 

 Thomson and Tait on Natural Philosophy. 



