300 Proceedings of Philosophical Societies. [April, 



they appear contemporaneous. Others (as at Trewavas Head, 

 the western side of Portcue Cove, Rosemodris, and Polmear 

 Cove), are so easily separable from the slate, and have walls so 

 distinct, that, under any other circumstances, they would be taken 

 without hesitation for true veins. 



" 12. Fragments of slate are visible in several of the veins, as at 

 Trewavas Head, St. Michael's Mount, Mousehole, Porth Just, 

 &c. I have not observed them in the main body of granite. 



" 13. At Mousehole, and at St. Michael's Mount, the slate is 

 intersected by numerous small quartz veins, some of which are 

 traversed by the granite veins ; others, on the contrary, traverse 

 and heave both the granite veins, and the other quartz veins. 



" 14. At Mousehole, and Whitesand Bay, where a junction of 

 the main bodies of granite and slate takes place, they appear, at 

 some points, so completely intermixed, as almost to exclude 

 any other idea than that of contemporaneous formation, 

 although, at other points, the junction is distinct and regular. 



" 15. In most other places where the junction occurs, the slate 

 reposes on the granite, without any appearance of a dislocation, 

 or disturbance of the strata, particularly at Portcue Cove, Cam 

 Silver, and Polmear Cove." 



After having thus described these curious objects of geological 

 inquiry, Mr. Came briefly examines the various opinions which 

 have been entertained respecting their origin and formation. 

 He then proceeds to describe the remaining veins of the doubt- 

 ful order; viz. veins of steatite, veins of calcareous spar, elvan 

 courses, and veins of oxide of tin. 



(To be continued.) 



Article XI. 



Proceedings of Philosophical Societies. 



ROYAL SOCIETY. 



Feb. 20. — The reading of a paper, entitled, Experiments on 

 the Velocity and Force of Sound, made at Madras, by John 

 Goldingham, Esq. FRS. was resumed and concluded. 



Mr. Goldingham commenced his paper with an account of 

 former experiments, calculations, and assertions, relating to the 

 velocity and force of sound, upon the diversities of which, he 

 stated, the experiments he was about to detail would probably 

 throw some light. He had made some experiments in the years 

 1793 and 1796, but the results of them had not been published ; 

 and more favourable circumstances for the prosecution of the 

 inquiry had since occurred. The experiments and attendant 



