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LIV. A Letter from Mr, R. E. Rafpe^ 
f, R, S, to M. Maty, M, D, Sec, R. S. 
containing a Jhort Account of fome Bafalt 
Bilk in Haflia 
Dear SiVy 
Gaficl, November 29, 1769. 
Read Feb. 8, 
1770. 
I 
HAVE lately difeovered in tha 
neighbourhood of this city, feveral 
hills, compoled of bafalt rocks, formed in polyedrous 
and mofUy pentagonal columns.. As this fort of ftone 
has hitherto met with few obfervers, and. affords many 
curious lingularities, 1 defire you to lay before the 
Royal Society, the following account of my re- 
fearches.. 
Our bafalt rocks differ from thofe of the Giant’s 
Caufeway in Ireland, by their want of articulation ; 
and from thofe anciently found at .Syena in Egypt, 
and deferibed with tolerable exadnefs by Strabo,, 
Lib. xvii. by their being lefs thick, and not ex- 
* The printifig of this paper was poftponed, cit account of 
the delays and difficulties which attended the fending of the 
plates, which the author dcfired miglit be executed ii> the btfl 
manner, under his eyes. 
ceeding 
