[ M4 ] 



theory on this fubjed, for which work indeed it does not appear 

 that any naturahft has hitherto colledled fufficient materials, and 

 as we would confider it rafhnefs in us to attempt fuch an under- 

 taking, confidering the (hort fpace of time we had to invefti- 

 gate matters, we will confine ourfelves to the following ob- 

 fervations : 



ift. The granite that forms the fouth fide of the mountains of 

 Glan, and extends acrofs the river of Oughterard as far as the 

 foot of Mahiramore, does not feem to be covered or interrupted 

 any where with any other fubflance. 



2d. It is not interfeded by any perceptible vein ; but one may 

 remark, about two hundred paces above the bridge of Oughterard, 

 fome veins or threads of fpar, fo minute as to be almolt imper- 

 ceptible, through which fome cryftals are interfperfed, whofe 

 greateft thicknefs does not exceed half an inch. 



3d. Thirty feet above the river, on the right fide, there are 

 feveral beds of granite, which feem to have been fradured by 

 fome violent force. The fpace between their numerous ruptures 

 is filled with fpar, which holds a great quantity of lead. 



4th. All the country in the neighbourhood of Oughterard 

 abounds with fcattered lumps of rolled granite, fo.Tie of which 



are 



