Geological Society. 575 



will also be observed that the book as a whole presents an orderly 

 development of a single beautiful theory with few 7 divergences 

 into by-paths, though with some indications of possible extensions. 

 In particular the two-dimensional or logarithmic potential is not 

 exhaustively treated in the same manner as the ordinary potential, 

 although the importance of the results obtained in respect of the 

 general theory oE functions is pointed out. The extension to space 

 of more than three dimensions is not treated in any detail. 



It is very unfortunate that a book otherwise so excellent should 

 bd carelessly printed, some of the misprints are of a most irritating 

 character. A. E. H. L. 



A History of Physics in its Elementary Branches, including the 

 Evolution of Physical Laboratories. By Elokian Cajobi, Ph.D. 

 New York : The Macmillan Company, 1899. 

 This is in many rejpects a disappointing book. The author has 

 endeavoured to write a history of experimental method in the 

 various branches of physics, rather than a historical survey of the 

 development of physical thought and ideas. The result is that a 

 large portion of the volume is made up of material gathered from 

 the ordinary text-books and somewhat amplified, to which short 

 biographies of the various physicists mentioned have been added. 

 As a concise collection of facts, most of which are well known to 

 the majority of teachers of physics, although gathered from various 

 sources, it may serve a useful purpose in directing a student's 

 reading ; but it can scarcely be regarded as an important contri- 

 bution to the history of physics. J. L. H. 



LV1. Proceedings of Learned Societies. 

 GEOLOGICAL SOCIETY. 



[Continued from p. 499.] 



January 18th, 1899.— W. Whitaker, B.A., E.R.S., President, 

 in the Chair, 

 HPHE following communications were read : — 

 -*- 1. ' On a small Section of Eelsitic Lavas and Tuffs near Conway 

 (North Wales).' By Frank Rutley, Esq., E.G.S. 



The rocks described in this communication were collected in 

 1877, in series, at short intervals, from a point at the mouth of the 

 liiver Conway near Bodlondeb. They consist of felsitic lavas and 

 tuffs, sometimes nodular, and generally exhibiting some variety of 

 fluxion -structure, corrugated, or banded. A specimen showing 

 brown bands is compared with one described by Iddiugs from 

 the Yellowstone Park. "What were once possibly red bands are 

 now represented by devitrified brown glass, and the change in 

 colour may have been due to the action of water upon the ferric 

 oxide which originally gave its colour to the glass. Some of 

 the rhyolites are tufaceous, and envelop fragments of rocks, some 

 of which were originally vitreous, others lithoidal. Coarser rhyolitic 

 tuff occurs at the northern end of the series. 



