1878-1879.] 345 



bearing rocks of the trappean area of Antrim and Deny form a 

 basin which, on being tapped by boring through the basalt, must 

 yield an abundant supply of good water. But the practical value 

 of such a communication depends upon considerations which seem 

 to have been overlooked by Mr. Traill. All things being equal, a 

 gravitation scheme is manifestly superior to a supply from wells of 

 any depth requiring pumping. This being chiefly an engineering 

 scheme, we need not discuss it here. But before any depreciatory 

 comparisons be drawn between our practice in Ireland and the 

 practice in some places in England, it should, in Mr. Gray's opinion, 

 be shown from a knowledge of the geology and physical geography 

 of the North, that gravitation schemes are not available for our 

 towns, either from a deficiency in the height of water commanding 

 the towns or from the defective quality of such waters. And he 

 was disposed to suspect that no such difficulty existed, when he 

 considered the schemes already projected for the supply of such 

 towns as Ballymena, Ballymoney, Cookstown, Coleraine, and Port- 

 rush. Let us take any point within the basaltic area and consider 

 the source and quality of the water. If the supply is to come from 

 the basalt, then there is a chance, if not a certainty, that the water 

 will be charged with iron. If we take our supply from the under- 

 lying Cretaceous rocks the water must be hardened by the lime ; 

 if we go deeper into the Keuper marls, we can scarcely avoid the 

 injurious effects of salt and gypsum ; and the waters from these 

 sources being beyond our reach, we cannot test them by chemical 

 analysis until expensive boring operations have been resorted 

 to. The height at which the Chalk is occasionally found around 

 the margin of the trappean area does not necessarily prove the 

 existence of a basin-like depression under the basaltic rocks. In- 

 deed, the more uniform level at which the Chalk occurs along the 

 entire boundary rather indicates that the intermediate beds below 

 the basaltic area are tolerably level, and the outcrop of the Chalk at 

 Templepatrick would indicate the same. But admitting the exist- 



