Mr. Moore's Remarks on the Origin of Rock-basins. 101 



The geographical longitude of ^| 



the pole of instantaneous ro- | 



tation, 

 The longitude of a given line >= A riot|ic 



quantity multiplied by 



lie time. 



in the body, 



The longitude of a fixed line 

 in the ecliptic, reckoned from 

 the first point of Aries, 



Thus the geographical latitude of the pole of the axis of 

 instantaneous rotation, the angular velocity of rotation, and 

 the obliquity of the ecliptic vary eternally within limits which 

 in fact are extremefy narrow, and thus the stability of the 

 system is preserved. 



I have only shown these results to be true when the earth 

 is supposed to revolve in a medium absolutely devoid of all 

 resistance and friction. It seems worthy of inquiry how they 

 become modified when some degree of friction is supposed 

 to exist. 



XIX. Remarks on the Origin of Rock-basins ; in reply to a 

 Paper by Mr. E. W. BRAYLEY, Jan.* By the Rev. THOMAS 

 MOOUE. 



To the Editors of the Philosophical Magazine and Annals. 

 Gentlemen, 



A N article on the subject of rock-basins, by Mr. Bray ley Jun., 

 ** extracted from his contribution, on the subject of Geo- 

 logy, to "The History and Topography of Devonshire,"a work 

 now in the course of publication, having been inserted, with 

 some slight alterations, in the Philosophical Magazine for No- 

 vember 1830, a place for some remarks in reply to his objec- 

 tions to the artificial origin of those cavities, is now requested. 

 Mr. Bray ley commences his observations in the work just 

 mentioned (page 288, 8vo edit.) by saying, " The writer of 

 these outlines might be considered as liable to a charge of in- 

 attention to his friend the Rev. T. Moore, author of the topo- 

 graphical and principal part of this work, were he to omit 

 noticing the remarks on the origin of rock-basins contained 

 in the first chapter of Book II." &c. The present writer, how- 

 ever, must take the liberty of observing, that, valuable as 



* See Phil. Mag. and Annals, N. S. vol. viii. p. .'531. 



Mr. 



