70 Geological Society : — 



cles tieferen, also durch zwei Tone im Einklang gebildet war-en, 

 diese Stosse auch au£ diesen Oberton gehort werden, man nitnmt 

 abergerade das G-egentbeil wakr, d. h. das der Grundton seine I,i- 

 tensitat periodisch dndert und dabei nur in den Momenten grbsster 

 Sehwachung den Jwheren Ton hervortreten liisst, ivie ich fruher 

 bescliriebenr 



With Mr. Bosanquet's permission, I will translate the words 

 in which Dr. Konig states what he observes, namely that " the 

 fundamental tone alters its intensity periodically, and thereby 

 allows the higher tone to come out only in the moments of greatest 

 enfeeblement, as I formerly described. 



I will leave to your readers to decide whether the alleged 

 injustice of my " careless sentence " is objective or subjective 

 in character; or whether credit for discovery is one of those 

 terms in the strict definition of which we are not to believe 

 "much." I remain, Gentlemen, 



Yours faithfully. 



University College, Bristol, SlLVANUS P. THOMPSON. 



December 19th, 1881. 



YIII. Proceedings of Learned Societies. 



GEOLOGICAL SOCIETY. 



[Continued from vol. xii. p. 75.] 



November 2, 1881.— Robert Etberidge, Esq., E.R.S., President, 



in the Chair. 



THE following communications were read : — 

 1. " On the Genus Stoliczkaria, Dune, and its Distinctness 

 from Parlceria, Carp, and Brady." By Prof. P. Martin Duncan, M.B. 

 Lond., F.R.S., E.G.S., Pres. R.M.S. 



2. " On the Elasticitv- and Strength-constants of Japanese 

 Rocks." By Thomas Gray, Esq., B.Sc, E.R.S.E., and John Milne, 

 Esq., F.G.S. 



In this paper the authors described the results of some experi- 

 ments made to determine the elasticity-constants and strength 

 against rupture and crushing of a few of the commoner Japanese 

 rocks, their chief object being to obtain data for calculating the 

 theoretical velocities of earthquake-wave transmission. The rocks 

 submitted to experiment were a grey granite, a pure Avhite crystal- 

 line marble, a greyish-green soft tuff', a mottled clay-rock, and clay- 

 slate. 



Young's modidi were determined by the bending of solid cylin- 

 ders of the rocks in an apparatus described and figured : the 

 deviations produced were read by means of the reflection from a 

 mirror, which magnified them more than 200 times. The process 

 for determining the rigidity was also described and illustrated by a 

 figure ; and the experiments in crushing were made upon columns 

 of stone by means of a Bramah press. In experiments on the 



