190 



SCIENCE. 



[N. S. Vol. VIII. No. 189. 



■once its purpose and test. In accordance with 

 this view, it might prove simpler, as well as 

 more honest and logical, to make any desired 

 concessions to usage as exceptions rather than 

 by introducing subsidiary rules of doubtful 

 sanction, such as the fifty-year limit. We could 

 then work with the ideal before us, and such 

 dififerences as continued to exist would concern 

 particulars merely. 



Many of the points treated in the various 

 codes are, relatively, matters of slight impor- 

 tance, and are doubtlesss capable of being set- 

 tled for all except the most cantankerous by 

 simple rules or by-laws which might accompany 

 a general platform or code, since in many such 

 matters usage furnishes the only criterion of 

 judgment and no logical or moral principles 

 are involved. Instead of being essentially com- 

 plicated, however, nomenclature is in reality 

 a very simple matter. Stability and uniformity 

 are the prime requisites, and these can be at- 

 tained under the binominal system by adhering 

 to the use of the oldest specific name without 

 regard to generic reference, and by confining 

 the application of a generic name to the genus 

 in which its assigned type or first binominal 

 species is included. The complicated and de- 

 batable nature of the various codes arises from 

 the neglect of these principles or from attempts 

 at limiting their application, either for avoiding 

 bibliographic labor or in the interests of usage. 

 O. F. Cook. 



U. S. National Museum, 

 July 27, 1898. 



SCIENTIFIC LITERATURE. 



SOME RECENT WORKS ON MECHANICS. 



A Treatise on Analytical Statics. By E. J. 



RouTH. Cambridge, University Press. 8vo. , 



Vol. I., pp. xii+ 407, 1891; Vol. 11. , pp. 



xii -f 224, 1892. 

 Traits de micanique rationelle. Par Paul Ap- 



PELL. Paris, Gauthier-Villars et Fils. 8vo., 



Vol. I., pp. vi + 549, 1893; Vol. II., pp. 



vi + 538, 1896. 

 The Elementary Principles of Mechanics. By A. 



Jay Du Bois. New York, John Wiley & 



Sons. 8vo., Vol. I., pp. x + 281, 1894 ; Vol. 



II., pp. viii -f 392, 1894 ; Vol. III., pp. x + 



296, 1895. 



Dynamics. By P. G. Tait. London, Adam 

 and Charles Black. 1895. 12mo. Pp. xii-f- 

 361. 

 Elements of Mechanics. By Thomas Wallace 

 Wright. New York, D. Van Nostrand & 

 Co. 1896. 12mo. Pp. viii + 392. 

 Applied Mechanics. By John Perry. New 

 York, D. Van Nostrand & Co. 1898. 12mo. 

 Pp. viii -f 678. 

 XJeher die Theorie des Kreisels. Heft I., Die 

 Kinematischen und Kinetischen Grundlagen 

 der Theorie. Von F. Klein und A. Sommee- 

 FELD. Leipzig, B. G. Teubner. 8vo. Pp. 

 iv + 196. 



The didactic excellence of the numerous 

 treatises on the principles of mechanics which 

 have appeared in recent years demonstrates an 

 increasing appreciation of the importance of 

 those principles and a progressive effort towards 

 brevity and lucidity in their exposition. The 

 doctrine of energy, now about half a century 

 old, has not only supplied new ways of visual- 

 ising the familiar and of investigating the un- 

 familiar in mechanics, but it has also forced us 

 to recognize the omnipresence of mechanical 

 phenomena. The growth of this doctrine and 

 the accompanying developments of the mathe- 

 matico-physicalsciences have furnished, during 

 the past twenty years especially, extensive ad- 

 ditions in subject-matter and in applications 

 not hithertOj available to writers of works on 

 mechanics. Almost equally important with 

 these additions in the way of material are the 

 improvements in terminology which have been 

 slowly but surely gaining general approval dur- 

 ing the present half century. The new points 

 of view afforded by the doctrine of energy, and 

 the critical spirit which has given precision to 

 the terminology, have led also to a revision of 

 the foundations of mechanics. Recent writers 

 devote much space to explanation, illustration 

 and discussion of the so-called axioms of the 

 science ; and the trend of current thought is 

 toward the conclusion that most of these axioms 

 are not such at all in the Euclidean sense, but 

 that they are facts of nature which have been 

 discovered by observation. Less stress than 

 formerly is now laid on alleged mathematical 

 proofs of mechanical principles and more at- 

 tention is given to the phenomena wherein 



