Geological Society. 221 



by Neumann (" Untersuchungen iiber das Logarithmische und 

 Newton'sche Potential")*. 



There is no attempt made at original investigation, for the notes 

 are professedly elementary in character, and to a great extent 

 reproduce work given in Todhunter's ' Analytical Statics ' and 

 Minchin's ' Statics.' Dr. Peirce has, however, carefully consulted 

 numerous other authorities, the most important works both by 

 English and Continental writers, and derives much of his matter 

 from original Memoirs. There are five chapters in all. In the first 

 the author treats of the Attraction of Gravitation ; in the second of 

 the Newtonian Potential Function in the case of Gravitation; in the 

 third of the same function in the case of Repulsion ; in the fourth 

 of the properties of Surface Distributions and of Green's Theorem 

 (also of Thomson's Theorem) ; and in the last Chapter he applies 

 his preceding results to Electrostatics. It will be thus seen that 

 the writer has endeavoured to meet the difficulty experienced by 

 his class of getting " from any single book in English a treatment of 

 the subject at once elementary enough to be within their easy 

 comprehension, and at the same time suited to the purposes of such 

 of them as intended eventually to pursue the subject farther, or 

 wished, without necessarily making a speciality of mathematical 

 Physics, to prepare themselves to study Experimental Physics 

 thoroughly and understandingly." To the list of 20 works recom- 

 mended to students, we would add such parts of Todhunter's 

 ' History ' as bear upon the subject. We have detected a few simple 

 misprints, but the " get up " maintains the reputation already 

 acquired by the printers and publishers. 



XXIII. Proceedings of Learned Societies. 



GEOLOGICAL SOCIETY. 



[Continued from p. 72.] 



January 12, 1887.— Prof. J. W. Judd, E.R.S., President, 

 in the Chair. 



THE following communications were read : — 

 I. " The Ardtun Leaf-beds." By J. Starkie Gardner, Esq., 

 F.G.S., E.L.S. ; with Notes by Grenville A. J. Cole, Esq., E.G.S. 



2. " On the Echinoidea of the Cretaceous Strata of the Lower 

 Narbada Region." By Prof. P. Martin Duncan, M.B., E.R.S., E.G.S. 



3. "On some Dinosaurian Vertebrae from the Cretaceous of India 

 and the Isle of Wight." By R. Lydekker, Esq., B.A., E.G.S. 



* In the Index to his ' History of the Theories of Attraction. . .' Mr. 

 Todhunter gives numerous references to articles in his book which treat 

 of the Potential. §789 assigns the introduction of the function, on the 

 authority of Legendre, to Laplace, but it is in §790 (to which he omits to 

 refer in the Index) that we learn that the term was first used by Green 

 (1828, Papers, p. 22 s ), and apparently independently by Gauss (1840) : cf. 

 also Thomson and Tait, Nat. Phil. vol. ii. §482. 



