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XVT. Oti (he DUJocations of the Strata of the Earth, 

 Btj Mr. John Fakey. 



To Mr. Tilloch. 

 rp SIR, 



± wo passages in my letter to you of the 2Ist of Msy iSOfil 

 (\o\. XXV. p. 45 and 46j, having occasioned inquiries from 

 dsfiferent friends, as to what I therein nieant, by the opera- 

 tions of gravihj upon the strata, ^' in circumstances which 

 have never yet been conlempla;ed aaiona; the physical in- 

 quiries of mathematicians," f beg the indulgence of your 

 readers (if you shall be pleased to favour me by the insertion 

 of this) to state, that some few months after I hud become 

 acquainted with Mr. IVilUam Smith's d.scoveries respectinfr 

 the strata, principally from considering the worn st »ie of 

 the edbics of the strata in the tissures, " [ was kd to con^ 

 sider an extension of the principles of gravity, which now 

 operate in producing the tides of the ocean, to the case 

 of a large satellitic body once probably revolving near to 

 the surface of the earth, and whose attraction heaved vp 

 the land, at the short intervals of return in its orbit, for 

 restoring the equilibrium, quicker than the waters could 

 run to form a tide capable of so doing, as at present. 

 Bv these supposed tides, and the ultimate fall of the sa- 

 tellite occasioning them, into the mass of the earth, 

 it should seem that I shall be able to account for all the 

 changes, observable or probable, between the state of a 

 sphere whose surface was uniformly covered with water, 

 nearly quiescent, and under which its stratification had pro- 

 ceeded with the most perfect regularity (something similar 

 to crystaiHzation) to the ruptured, auraded, and dislocated 

 form, m which the drv land now appears, projecting above 

 the nearly spheroidal figure assumed by the ocean." 



The articles Coal, CUIicrius, and others expected to suc- 

 ceed them in Dr. Rees's Neio Cydcpa-dia, will, it is hoped, 

 tend to a further elucidation of this subject. I am, sir. 



Your obedient servant, 



John Fj\rey. 



\2, Upper Crown-street, Westminctcr, 

 July 14, 1B07. 



XVII. His- 



