hood, the subterranean pool being frequently of small extent, 
and of the nature of a channel, and may circulate in irregular 
trenches between impermeable strata. The determination of 
the existence of these wells beforehand is a very difficult 
matter, especially in a locality where no borings have been 
previously made; when a hole is bored down through this 
upper impervious stratum to the surface of the Lake below, the 
water will be forced by the natural law of water seeking its 
level, to a greater or less height according to the elevation of 
the feeding column. 
