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to find an opportunity of explaining the nature of Basalt 

 and Volcanic Trap, which has caused so much argument 

 amongst men of science as to its nature and origin. 



The upper specimen shows an almost independent largish 

 crystal. 



The lower specimen is a considerable group of small 

 crystals, with sometimes curved or concave faces, marked 

 with diagonal strias : — see the lateral magnified figure. 



This substance in these shapes occurs in many parts 

 abroad, as well as in Scotland ; but I do not know that it 

 has been mentioned as found in Ireland till now. 



