Geological Society/. 203 



p instead of w. The radius of a wire is y, the specific gravity of a 

 metal is d. The letter p is also used for a number of layers of 

 wire. Instead of log. here I. is conveniently used, but Zis also used 

 to indicate a length. 



After all, these do not delay the progress of the earnest student. 

 It is only when the printer uses I and I. indifferently fcir log., and 

 mingles his letters curiously in mathematical formulae, and leaves 

 out very important half-brackets, and perhaps in the same page 

 uses I to represent also a length, that the student has a right to 

 complain, and it is only fair to say that the printers' errors in 

 this volume are much too numerous. 



We note that the authors are careful in almost every case to 

 give the names of the various scientific men whose \^ork they make 

 use of. One noticeable exception is the name of Prof. Tait, in the 

 description of his beautiful geometrical treatment of the damping 

 of vibrations. 



Although we have said that the book will benefit by some revision, 

 we think that Dr. Atkinson, in undertaking and carrying out this 

 translation, has done a very great ser\ice to, and will receive the 

 thanks of, a very considerable number of electricians. 



XXIII. Proceedings of Learned Societies. 



GEOLOGICAL SOCIETY. 

 [Continued from p. 78.] 



December 5, 1888.— W. T. Blanford, LL.D., F.R.S., President, 

 in the Chair. 

 T^HE following communications were read : — 

 -*- 1. " Notes on two Traverses of the Crystalline Rocks of the 

 Alps." By Prof. T. G. Bonney, D.Sc, LL.D., P.R.S., F.G.S. 



These journeys were undertaken in the summer of 1887, in the 

 company of the llev. E. Hill, P.G.S., in order to ascertain whether 

 the apparent stratigraphical succession among the gneisses and 

 crystalline schists which the author had observed in the more cen- 

 tral region of the Alps, held good also in the Western and Eastern 

 Alps. At the same time all circumstances which seemed to throw 

 any light on the origin of the schists were carefully noted. The 

 author examined the rocks along two lines of section : — (1) By 

 the road of the Col du Lautaret from Grenoble to Briangon, and 

 thence by the Mont Genevre and the Col de Sestrieres to Pinerolo, 

 ou the margin of the plain of Piedmont. (2) From Lienz, on the 

 upper waters of the Drave, to Kitzbuhel ; besides examining other 

 parts of the central range, east of the Brenner Pass. The specimens 

 collected have subsequently been examined microscopically. 



The results of the author's investigation may be briefly sum- 

 marized as follows : — 



(1) While rocks of igneous origin occur at all horizons among the 

 crystalline series of the Alps, these, as a rule, can be distinguished ; 

 or, at any rate, even if the crystalline schists in some cases are 



