72 REPORT — 1855. 



placed at considerable elevations above the ground, they probably indicate 

 much less than the real quantity of water reaciiing the surface. By these 

 observations the average annual rain is about '20 inches, but allowing for 

 the probable error, and assuming it at 25 or 26 inches, from which an annual 

 loss of 15 or 16 inches must be deducted, there will remain only about 10 

 inches to supply floods and percolation, just half the quantity which remains 

 at Liverpool and Manchester. As at those places it appears that muchmore 

 water runs off in floods than remains both for floods and percolation at Wol- 

 verhampton, and as undoubtedly a large portion of the water will also run off 

 the ground in floods in that district, a very small quantity can remain to give 

 a constant supply to deep wells. 



In all cases the red sandstone water has to be pumped out of the rock 

 by artificial means. Except where the rock is very porous, and where the 

 downward tendency of the water is little interrupted by intervening beds of 

 shale, and where only it is abundantly supplied by rain on the surface, no 

 large, convenient, or cheap supplies of water can be expected. The hard- 

 ness of the Manchester water at the Gorton well was about 20°, of the water 

 at Wolverhampton about 18°. 



Some small supplies have been obtained by bore-holes in the coal-measures, 

 particularly where they are covered by the new red sandstone ; but they are 

 comparatively of small moment. 



3. From rivers. — It has been so easy and natural a course to resort 

 to rivers for a supply of water to towns, as the springs or local supplies on 

 which they originally depended have failed or become exhausted, that except 

 in districts where the streams have been greatly polluted, recourse to con- 

 tiguous or convenient rivers has been a common practice. Thus the Seine 

 has contributed a large portion of the supply to Paris. The Thames and the 

 Lea contribute the bulk of the water consumed in London. The Clyde 

 afl^brds the main supply to Glasgow. The Ouse supplies York ; the Lee, 

 Cork ; the Trent, Nottingham ; the Dee, Chester ; the Tyne formerly 

 supplied Newcastle, and the Wharfe has just been laid under contribution 

 for the wants of Leeds. 



In general, however, rivers are being abandoned where other sources are 

 within reach, partly from the fouling of the streams by the drainage of 

 towns and by mining and manufacturing operations, and partly on account of 

 the frequent discoloration of the water by floods or vegetable decomposition, 

 and the difficulty of purifying the water so discoloured even by the expensive 

 and troublesome system of careful filtration. But where the rivers are pure 

 and free from discoloration, and local circumstances favour the adoption of 

 such a supply, it possesses many and great advantages. The requisite works 

 are simple and capable of easy extension, and the supply generally is most 

 abundant. Such are the cases of Inverness, Aberdeen, and Perth, all deri- 

 ving their supplies from rivers of unexceptionable quality. 



River- water also possesses to a great extent a power of self-purification, so 

 that a moderate admixture of foul water in the upper part of a stream does 

 not necessarily render the water unfit for the supply of a place lower down in 

 its course. In the case of the river Wharfe, lor example, from whence the 

 town of Leeds is to be partially supplied with water, Dr. Hofmann was unable 

 to detect the presence of any noxious ingredient at the point at which it was 

 proposed to withdraw the water, although it received the drainage of several 

 small towns and villages, and the refuse of several woo'len-mills situated at no 

 great distance higher up on the river. The case, however, of the deleterious 

 character of the water of the Thames is notorious, and I need scarcely cite 



