VOL. LXXX.] PHILOSOPHICAL TRANSACTIONS. 63Q 



stituent part of water, with phlogisticated air, is taken into the growing sub- 

 stance. Thus the phlogisticated and light inflammable airs are brought together 

 by the process of vegetation. 



IX. On the Strata and Volcanic Appearances in the North of Ireland and 

 Western Islands of Scotland. By Abraham Mills, Esq. p. 73. 



At Moneymore, in Ireland, Mr. M. first perceived tumblers of lava ; hence 

 by Maghera, Garvagh, Coleraine, Portrush, and to Bush-Mills, lava is conti- 

 nually seen, either in solid masses, forming the basis of the vegetable soil, or 

 else in tumblers dispersed over the surface. He employed 2 days in studying 

 the various appearances at the Giant's Causeway, and regretted being obliged to 

 quit it so hastily. So much has been already said on this spot, that he only re- 

 marks that the red ochry joints between the beds of rude lava, and the different 

 heights at which the basalt pillars are seen, give probability to the conjecture, 

 that the whole mass has been the produce of several successive eruptions. He 

 embarked at Port Ballintrea, and after ] 2 hours sailing arrived at Hay, where, 

 inspecting the lead mines, it was impossible to avoid noticing the singular ap- 

 pearance of those masses which run in a kind of veins in various directions, and 

 are called Whyn Dykes, which had in some places a basaltic appearance. 



On returning from Hay he landed at Portrush ; and, in his way to Ballycastle, 

 viewed the Giant's Causeway from the top of the cliffs, and was much struck 

 with seeing below, in the 4th or eastern bay, a kind of Whyn Dyke, which ran 

 into the sea towards the n. n. e. Examining the cliffs at Ballycastle, he found 

 the horses, or faults, of which there are several between the coals, were veins of 

 lava, resembling the Whyn Dykes of Hay, standing vertically, intersecting the 

 various strata of coal and freestone, and running into the sea. The largest of 

 the veins or Whyn Dykes is near 12 feet in breadth, and ranges n. by e. and s. 

 by w. 



Returning to Dublin, through Clogh, Ballymena, Antrim, Glanevy, Moira, 

 Banbridge, Loughbrickland, and to within a short distance of Newry, he con- 

 stantly saw tumblers of lava, and in some places the fixed mass of lava, in which 

 were fissures ranging n. e. and s. w. When Mr. M. reached home, his mind 

 being strongly impressed with the similitude between the Hay Whyn Dykes and 

 those of Ballycastle, which take their rise in a country confessedly abounding 

 with volcanic matter ; that he might be enabled to form a better judgement of 

 their substance when he should again visit Hay, he repeatedly and attentively 

 examined the Derbyshire and toad-stone in the neighbourhood of Buxton, and 

 found it very like the specimens of the Whyn Dykes, which he had brought 

 from Hay. 



Early in the last summer Mr. M. again visited Ireland, and having spent some 



