. 3« 



it through its middle, and one on each fide of this, about a foot 

 diftant. 



Thefe three lines determine the ftile of mafonry (if I may ufe the 

 expreffion) with which it is built, to wit, horizontal prifms about five 

 feet long, laid in rows on each fide, and in the middle two rows of 

 prifms about one foot fquare each. I itttempt a fketch of thefe lines thus: 



The bafes of the long prifms Iliew their polygonal figures on the fides 

 of the Dyke, and, if taken up and laid horizontally, would exhibit a 

 rude pave; thefe prifms are obvioufly compofed of fmaller ones like 

 Aofe at Port Spagna, but I had not a fledge fuiEciently weighty to 

 afcertain the faft with preciiion. 



When I was on the fpot Mr. Magawly, who is concerned in, and 

 fuperintends the colliery, told me they were then cutting acrofs this 

 Dyke feven hundred yards within the precipice. 



The next Dyke is of ruder bafalt, and more imperfeftj k feems to 

 -exhibit nothing remarkable. 



The fourth Ballycaftle Dyke, or as it is called there the Great Gaw, 

 .emerges from beneath the precipice, of the fame breadth and of the fame 

 rude material and conftruftion with the firfl: and third ; but it is foon 

 joined by what the colliers call its wing, that is a new wall annexed to 

 it on each fide, by which it becomes triple; thefe wings are of a very 

 • different material from the centre, being precifely the fame in grain 

 with the very fine Portrufli flone, which fometimes contains fliells and 

 impreflions of cornua ammonis, but in thefe wings I did not obferve 



any. 



Whea 



