Geological Society . 149 



indicate wherein this edition differs from that previously noticed. 

 The third edition closed with chapter xi. on Mean Value and 

 Probability, this is now chapter xii., chapter xi. being devoted to 

 Multiple Integrals (including an account of Diri chiefs Theorem, 

 Green's Theorems, and applications to Spherical Harmonics). 

 Chapter xiii. is on Fourier's Theorem. The novelties of this last 

 edition are the two concluding chapters. Chapter xiv. treats of 

 Line and Surface Integrals (discussing the theorems named after 

 Stokes and Neumann) : it is a short one and takes up pp. 401-412, 

 concluding with a modification of Sir W. Thomson's theorem on 

 the distribution of electricity on spherical conductors. In chapter 

 xiv. Dr. Williamson gives an account (pp. 413-446) of the appli- 

 cation of the Calculus of Variations to the determination of Curves 

 possessing maxima and minima properties. 



Students who require a further development than is given here 

 are referred to the writings of Jellett, Carll, and Moigno. The 

 work is supplemented by a large collection of Exercises and a 

 sufficient Index. We can only hope that the author's labours may 

 meet in the future with a success equal that which they have 

 already attained. 



Solutions of Examples in Qonic Sections, treated Geometrically. By 

 W. H. Besawt, Sc.D., F.R.S. London : George Bell, 1890. 



We have recently received this copy. As the book is in a third 

 edition, it has evidently met a want. To our cost we know that we 

 have spent many " ten minutes " in the unravelling of the Geo- 

 metrical " Conundrums " contained in the author's " Conies." It 

 is now interesting to compare our solutions with those before us, 

 which though generally very concise furnish the student with a 

 closely fitting Key to all the Problems. The book is most accept- 

 able, but we trust that junior students will not have recourse to it 

 until they have done their best in attempting to solve the Exercises 

 themselves. A subsequent comparison of their own work with 

 that of this " companion " volume will d-o them much good. 



XIV. Proceedings of Learned Societies, 



GEOLOGICAL SOCIETY. 

 [Continued from vol. xxxii. p. 230.] 



November 11, 1891.— Sir Archibald Geikie, D.Sc, LL.D., F.R.S., 

 President, in the Chair. 



THE following communications were read : — 

 1. "On Dacrytlierium ovinum from the Isle of Wight and 

 Quercy." By E. Lyddeker, Esq., B.A., E.G.S. 



2. " Supplementary Remarks on Glen Roy." By T. P. Jamieson, 

 Esq., E.G.S. 



The author discusses the conditions that preceded the formation 

 of the Glen Roy Lake, and appeals to a rain-map of Scotland in 



