ylceount of the WHYNN DYKES in the Neighbourhood of the GIANT'S 

 CAUSEWAY, BALLYCASTLE, and BELFAST, in a Letter to 

 the LORD BISHOP OF DROMORE, from WILLIAM RICH- 

 ARDSON, D. D. late Fellow of TRINITY COLLEGE, DUBLIN, 

 Ready April i3, 1802, 



My Lord, 



When I laft had the honour of converfing with you on 

 bafalt fubjefts, you were furprifed when I told you that the Whynn 

 Dykes, which of late have fo much occupied the attention of naturalids 

 in the Weftern Mes of Scotland, originated on our Irilh coafl, and 

 efpecially about the Giant's Caufeway. 



As your Lordfliip expreffed a wifli for further information on the fub, 

 jeft, I promifed to communicate to you fuch obfervations as I fliould 

 make when I had examined the coaft a fecond time, in order to afcer. 

 tain the fa{ls with the utmoft precifion. 



Previous to my entering into a particular account of our dykes, I will 

 take the liberty of making a few general obfervations on thofe in both 



countries. 



The Whynn Dykes in the Hebrides are feen under very different cir- 

 cumftances from thofe on the northern coaft of Ireland. There they 

 are found on, and above, the furface, generally a few feet ; and often 

 ferve as fences, whence they obtain their name. In this form they run 

 northwards quite to the extremity of thefe iflands, afcending and de- 

 fcending mountains, croffmg feas, and where thefe are narrow, the Dykes 

 that run into the water at one fide of a channel, are feen rifing out of 

 it at the other fide, fteacjily purfuing their formed reftilineal courfe. 



With us they are fometimes exhibited in a very different manner. 

 Their firft appearance is in the faces of our vaft perpendicular precipices, 



where 



