Economic Geology. 31 



to a circumstance of this nature would inevitably prove 

 unsuccessful. When the deposits rest in basins these 

 observations are of much importance, since by neglecting 

 them the bore might be commenced on the verge of the 

 porous strata, instead of at some distance within the basin ; 

 and in such a case as no pressure would be exerted on 

 the water the establishment of an overflowing well would be 

 impracticable. A clear apprehension of the general princi- 

 ples on which the Artesian method depends will suggest 

 several minuter sources of failure, but it is unnecessary to 

 specify these in detail, since on careful examination of the 

 locality they would not escape notice. Improvements in the 

 mechanical department of boring, will, it may be expected, 

 gradually diminish the risk of failure from the depth to 

 which the porous or impervious beds may extend, and also 

 from the tenacity or hardness which the latter may possess. 

 The first mentioned sources of failure can only be discovered 

 and guarded against by the aid of the geologist, and we 

 repeat again, that no boring operations ought ever to be 

 undertaken irrespective of the information he is able to 

 afford, otherwise there is no reasonable warrant for the 

 expense their prosecution involves. 



We have hitherto spoken of boring exclusively as a prin- 

 ciple, but in conclusion it may be remarked, that it is not 

 unfrequently useful as an auxiliary in meeting demands for 

 increased supplies of water. When a water-bearing stratum 

 is pierced by the auger, and the water is found to rise only 

 partially in the bore, a common well may then be sunk 

 down to this level, and the bore will act as its feeding pipe. 

 The comparatively slight expence of boring admits of its 

 extensive employment in this way, and it is peculiarly appli- 

 cable in doubtful localities, where the great outlay required 

 for a common well of considerable diameter, combined with 

 the possibility of its being ultimately unsuccessful after all, 

 would effectually prevent its being resorted to. 



