465 



No doubt, igneous fufion would at once fatisfaftorily account for the 

 want of a particle of fluid water in thefe majfes : let us try the fad ; 

 I have frequently met with, in columnar bafalt, cavities filled with freih 

 water ; I particularly'refer to the (tratum open at Ballylagun, two miles 

 fouth from Portrujh ; it is prifmatic and columnar, and almoft every 

 (lone when broken, contains cavaties filled with frefli water. 



Sometimes too, contiguous to the Giant's Caufeway itfelf, I have found 

 water in prifmatic bafalts, which I fufpeft had fallen from an upper 

 ftratum of pillars. 



As tbefe fa£ls fo pofitively contradift Dr. Hutton's afiertion, which 

 he puts fo ftrongly ; and as they are obvioufly fatal to all Theories which 

 fuppofe bafalt to have been once in fufion, but have not (as far as I 

 know) been obferved by any other Naturalift, I am happy to have my 

 folitary teftimony confirmed by moft refpeftable authority. 



The Hon. Mrs. Stuart of Armagh, vifited the Giant's Caufeway 

 laft fummcr, and in one of the flones lying near it, which fhe had 

 (among many others) direfted to be broken, found in the infide of 

 it, a cavity containing near two tea fpoons full of water, alfo a nodule 

 which ftie was fo kind as to ftiew me ; it was a rounded rufty flone 

 about the fize of a marble, the interior was very fine chalcedony, coated 

 with a ftony fubftance of which the outfide was fmooth *. 



Vol. IX. ( 3 N ) Dr. 



* This is not the only faft Mrs. Stuart difcovered, which had efcaped the notice of fo 

 many Naturahfts who have vifited the Giant's Caufeway, and even publilhed accounts of it. 



Mrs. Stuart lliewed me in the Colleflion ftie had made, a number of fmall neat prifms, 

 triangular, quadrangular, and trapezoidal, the fides of the very fmalleft lefs than half an 

 inch ; of thefe minute prifms laid horizontally, our vertical Whys Dykes are formed. 

 [See a preceding Memoir in this vol. upon Whyn Dykes.] 



How a bafalt, differing confiderably in grain, and totally in form, from the contiguous 

 Giant's Caufeway bafalt, could fo long have efcaped notice, is beyond my comprehenfion ; 

 but neither Dr. Hamilton, nor any other writer, mentions thefe minute prifms, nor have I 

 met with them before in any colkftion of bafalt fpecimens, except where I depofitecj them 

 myfelf. 



