Geological Society. 219 



upon papers by Dr. Eobinson in the ' Irish Transactions ' (1850) 

 and by Prof. Stokes in the ' Proceedings of the Royal Society ' 

 (1881). In Chapter IV. " Eigidity of Cords " is considered in 

 connexion with Friction. In Chapter Y. some articles are intro- 

 duced upon " Screws " in connexion with the articles upon 

 " Composition of Rotations ;" and articles on " Finite Rotations " 

 replace the former articles on " Moving Axes and Relative Motion " 

 and " Motion relative to the Earth : " these new sections contain 

 Rodrigues' Theorem, Sylvesters Theorem, Conjugate Rotations, and 

 Composition of Screws. In Chapter VI. there are some additional 

 articles, and a few of the old ones have been removed, but the 

 chief divisions remain unaltered. Chapter VII. has undergone 

 more change than has fallen to the lot of the previous chapters : 

 the articles on " Principles of Least Action and Varying Action "are 

 relegated to the second part, as are those on the " Theory of moving 

 axes and of Motion relative to the Earth " (of old Chapter V.), 

 and Chapters IX. to XII. of the third edition. The Theory of 

 small oscillations with several degrees of freedom both about a position 

 of equilibrium and a state of steady motion, and the Theory of forced 

 oscillations are also to form part of the advanced course. 



Lagrange s Equations, the Theory of reciprocation and Sir W. 

 Hamilton's Equations, the modified Lagrangianfunction,non-conserva- 

 tive forces, and indeterminate multiplier siorm the contents of Chapter 

 VIII. Chapter IX. contains elementary portions of old chapter VIII. 

 on "Small Oscillations;" and Chapter X. is devoted to some special 

 problems on Oscillations of a rocking body in three dimensions, of Cones 

 in three dimensions, Large Tautochronous motions, and Oscillations of 

 Cylinders and Cones to the Second Order. 



The whole book bears evidence that the author has worked upon 

 this new edition con amore, and has done his utmost to bring the 

 treatment as near to perfection as possible. Such a work reflects 

 the highest credit upon the University that has assisted at its birth ; 

 and the principle of " thorough " which prevades every part ex- 

 plains how it is that the writer is so successful a teacher. 



XXXI. Proceedings of Learned Societies. 



GEOLOGICAL SOCIETY. 

 [Continued from p. 65.] 



January 10, 1883.— J. W. Hulke, Esq., F.R.S., 

 President, in the Chair. 



THE following communications were read: — 

 1. "On the Lower-Eocene Section between Reculvers and 

 Heme Bay, and some Modifications in the Classification of the 

 Lower London Tertiaries." By J. S. Gardner, Esq., F.G.S. 



The author noticed Prof. Prestwich's classification of the Lower 

 London Tertiaries, and the introduction by the Survey of the term 

 " Oldhaven Beds " for some of his basement beds of the London 

 Clay. He next discussed the conditions under which the Lower 

 Tertiaries were produced, and showed that throughout the Eocenes 



