ORIGIN OF BASALT. £83 



tion to any thing suggested from such high authority, I took Facts and ob- 



mv friend, Mr. Joy, to the spot where I used to find the water servations re- 



J ' / , ^T^ „ 1 s TTr 1 1 specLing basalt 



in the greatest abundance (Ballylagan). We broke several j^ t^e county 



stones, and, where we found water, observed that, at first, it of Antrim ; ad- 

 wet the whole fracture evenly ; but, as it evaporated gradually, ^^^^ -^ °g ^^^ 

 the wet was confined to cracks, diverging from the little ca- volcanic. 

 vity that had contained the water. These, therefore, we at 

 first supposed must have been the passages through which the 

 water had made its way: but, on attentively examining the 

 cracks, we perceived that, as they radiated from the cavity, 

 they diminished in breadth, and finally terminated in the 

 solid stone; of course, that the water had not come in by 

 them. ' 



Another fact seems conclusive against percolation. I never 

 found, in our basalt, any cavities but those which contained 

 water, or which bore evident marks of having been once filled 

 with it. We have, therefore, this alternative: 



Either the water first made its way through the compact 

 tissue of the basalt, then collected, and dilated itself with such 

 force, as to form rounded cavities, often larger than a pistol- 

 bullet, which, on many occasions, it afterwards forsook: 



Or, we must admit the water to have been coeval with the 

 basalt: to which, of course, we Cannot ascribe an igneous 

 origin. ' 



Sixthly. As we know the high state of ignition in which 

 lava issues from a volcano, it is reasonable to expect that,, 

 ' when,, in its course, it meets with extraneous substances, it 

 should produce upon them such alterations as are the usual 

 effect of intense heat, applied to these same substances. Basalt, 

 likewise, is often found in contact with similar matters. Hence, 

 by a minute examination of these contacts, we have an ob- 

 vious mode of ascertaining, whether the basalt also had en.- 

 countered them in the same state of ignition we know the 

 kva did. 



As my country, to a great extent around me, is composed 

 of nothing but basalt and lime-stone, I have no other substance 

 but lime-stone upon which I can make observations. This, 

 liovvever, I apprehend, will be found abundantly sufficient to 

 decide the question. 



About one hundred yards fiwm the beautiful cavern, called 



Long 



