336 Mr. Brayley, Jun., on the Connection of 



rately described by Borlase, as evincing the Druidical origin 

 and application of these basins ; and the fallacy of some of 

 which has been acutely pointed out by the author of " Philo- 

 sophy in Sport made Science in Earnest, 5 ' in the additional 

 notes to that ingenious work, vol. iii. p. 170 et seq. 



Nothing remains to be said, in this place, on the alleged 

 Druidical origin of rock-basins ; but the writer is unwilling 

 to quit so interesting a subject, regarding it in a scientific 

 point of view, without adverting to some inferences connected 

 with it, which have recently occurred to him, drawn partly 

 from the researches of Dr. Macculloch and other geologists, 

 and partly from his own very limited observations ; respecting 

 the internal concretionary structure ascribed to the granite of 

 this formation. 



Dr. Macculloch has attributed the " even and rounded 

 concavity" of the rock-basins, to the " uniform texture of the 

 granite;" and agreeably to this opinion, it has been attributed, 

 in the foregoing remarks on Mr. Moore's objections to the 

 equality of action permitted by this uniformity; as being, per- 

 haps, the more strictly accurate mode of stating the fact. But 

 may not this figure, which, in some instances, Dr. Macculloch 

 has remarked, is as " regularly spheroidal internally as if they 

 [the basins] had been shaped by a turning lathe," be, in reality, 

 principally owing to that concealed spherical or rather sphe- 

 roidal structure, the existence of which, in the same granite, 

 has been rendered so highly probable by that eminent geo- 

 logist? For it appears to be obvious that the same variation, 

 in some given ratio from the centre, of the resistance to disin- 

 tegration of a mass of granite, which has led to the separation 

 of the granite of this formation into prismatic and cuboidal 

 blocks, will, when one surface only of the rock is acted upon, 

 and that only at certain points, give rise to cavities having a 

 figure which is precisely that of the rock-basins. And in- 

 deed it would appear that some further cause than the equality 

 of action permitted by the uniformity in texture of the granite, 

 must in reality operate in the formation of these regular sphe- 

 roidal basins; for if that only were the cause, the granite 

 should be as much acted upon in a direction perpendicular to 

 its surface, as in those directions which are parallel to it; so 

 that the depth of the basins ought always to be equal to their 

 diameters, or nearly so; which, so far as the writer's knowledge 

 extends, is seldom, if ever, the case. The occurrence of the rock- 

 basins on the vertical faces of the granite at Scilly, would seem 

 to be a further corroboration of this idea; for it is difficult to 

 conceive how the action of water could produce such cavities 

 in this situation, unless it were aided by the tendency of the 



rock 



