38 



*' mafs of bafaltcs that forms the northern extremity of Fairhcad, has 

 " defcended over the adjoining ftrata," and that he has it ready " to 

 " /// uj) each cleft and vacuity." (Ham. Antrim, let. 5 part i.) 



I will alfo admit in favour of Dr. Hutton, that he has his unerupted 

 lava ready at the bottoms of thefe chafms, that he has his machinery 

 prepared for forcing it up, and that he has furmounted his great difEculty, 

 and difcovered a mode of fupporting fuch a mafs when railed ; a point 

 upon which, having failed himfelf, he would difcourage others from form- 

 ing conjeftures. (Edinburgh Tranf. vol. i page 285.) 



Notwithftanding thefe concelllons it will not be difficult to fliew that 

 thefe gentlemen have not difcovered the fecret of nature in the conftruc- 

 tion of thefe Angular walls, and that tliey were not formed by liquid 

 lava filling up mighty chafras. 



I ft. Many of our contiguous Dykes differ materially from each other, 

 yet their proximity is fuch, that according to the theory of either Dr. 

 Hamilton or Dr. Hutton, they mud: have been filled up from the fame 

 fource, and with the fame material. 



2dly. Many of thefe Dykes, both in Ireland and Scotland, fliew a 

 material difference between their middle parts and their fides, both in 

 grain, and internal principle of conftruftion ; the change too is not gra- 

 dual, but per faltum, as if the diffnnilar parts were feparated from each 

 ■other by planes parallel to their fides; all this is perfectly uicompatible 

 with the high ftate of fluidity in which the lava muft have been, to 

 enable it to fill up vafl chafms of fuch diminutive breadth. 



3dly. Our Whynn Dykes come in contaft with a great variety of dif- 

 ferent fubftances, without producing fuch effeft upon any one of them, 

 as might be expefted from the contiguity of fo glowing a mafs; but 

 however this argument may bear againft the Volcanijisy the Fluionifts 

 will fay it does not apply to them, for the chemical operations of nature 

 are carried on in Dr. Hutton's fubterranean laboratory very differently 

 from what we fee on the furface of our globe, in the former Dr. Hutton 

 Ja^s calcareous Jirata are confolidated by the operation of heat andfimplefufion, 

 and again, having proved that^ thefe Jirata had been confolidated byfimple 



fufion 



