SCIENCE-ADVERTISEMENTS 



THE 

 PRINCIPLES OF 

 STRATIGRAPHY 



BY 

 AMADEUS W. GRABAU. S.M.. S.D. 



PROFESSOR OF PALEONTOLOGY IN 

 COLUMBIA UNIVERSITY 



"Should be on the reference shelf of every col- 

 lege, normal school, and large high school in the 

 United States." — Journal of Geography. Vol. XIII, 

 Jan. 1915. 



8co, 1150 pages, 264 iUastrationi. Price, $7.30 



Deicriptive Circular Sent upon Request 



k. G. SEILER & CO. 



NEW YORK CITY 



THEORY OF INVARIANTS 



By OUVER E. GLENN 



The University of Pennsylvania 



254 pages With Diagrams. 



S2.75 



A book of ten chapters, which aims in 

 moderate space to give an adequate intro- 

 duction to the study of original memoirs. 

 The Aronhold symbolism is introduced early 

 in the course, but much emphasis is placed 

 upon the methods of the great English 

 mathematicians. 



The chapter titles are: I, The Principles 

 of Invariant Theory ; II, Properties of In- 

 variants ; III, The Processes of Invariant 

 Theory; IV,Reduction; V.Gordan's Theorem; 

 VI, Fundamental Systems; VII, Combinants 

 and Rational Curves; VIII, Semin variants. 

 Modular Invariants; IX, Invariants of 

 Tenary Forms ; X, Appendix ; Theorems 

 and Exercises. 



GINN AND COMPANY: Publishers 



Boston New York Chicago London 



R¥HRD HFRieHN STUDIES 



A new series devoted to African anthropology in its widest 

 sense, and comprising annual volumes of short papers and 

 occasional monographs. 



Now ready. Volume I, xiv + 292 pp., 30 heliotype ph., 

 30 photolitb ph., many text figs., handsomely bound in Cloth 



Contains articles on ancient Egyptian fishing, Benin bronzes, 

 Egyptian archeology, Swahili didactic literature, etc. 

 Copies may be obtained by sending $10.00 to the Assistant 

 Editor, H. A. S. 



HFRieHN DEPARTMENT ©F THE PEHB0DY MUSEUM 

 Harvard University Cambridge, Mass. 



