riCTNITT of EDINBURGH. 421 



ftate; while it differed from No.- 37., the ftone on the fides, 

 which were perfectly fimilar to each other in compofi- 

 tion. 



Tracing the friable purple-coloured portion upwards, I 

 found it gradually became harder, and, of a fudden, change to a 

 fine-grained blue-coloured greenflone ; and the p art correspond* 

 ing with the included mafs, alter to a hard coarfe-grained rock, 

 (No. 38.) I foon obferved, that this coarfe-grained mafs, which 

 is about ten inches thick, continued upwards, maintaining an 

 uniform dimenfion and pofition, in refpect. to the walls of the 

 vein, as high as the eye could trace it in the rock, thus divid- 

 ing it into two portions j that on the left fide being about eigh- 

 teen inches wide, while the other is about five feet. 



On comparing the texture of the included ftripe, with that 

 of the walls on each fide, (No. 39. left fide; No. 40. included, 

 flripe; No. 41. right fide,) taken in a horizontal line, about fix 

 feet above the flrata, I found as clofe a refemblance as it is poffible 

 to conceive ; they are all coarfe-grained, and highly cryftallifed. 

 This fimilarity is not more remarkable, than the difference be- 

 tween the fubftance of the vein and the included mafs. Speci- 

 mens taken from the junction of thefe, mark this in a ftriking 

 manner. No. 42. is from the left fide of the right portion of 

 the vein, to which the fine-grained part belongs. No. 43. is 

 from the middle of this portion ; and No. 44. from the fide 

 next the right w^all. Thefe were alfo taken in a horizontal 

 line, and exhibit the fame gradation of grain noticed as 

 exifling in the great bed. Even in the narrow portion of 

 eighteen inches, on the left fide, this circumftance is quite vi- 

 fible; but the fpecimens taken from the other are highly illu- 

 ftrative of the fad. 



