76 REPORT — 1855. 



to our knowledge on this subject. Most large modern undertakings have 

 been laid out on this principle, and the constantly accumulating information 

 enables the engineer to revise his data, to correct errors, and to make his 

 calculations with additional certainty. To enumerate the works on this 

 principle would be to name most of the important water projects of modern 

 date in this country and in America. The Croton Aqueduct, constructed 

 between ihe years 1835 and ISiS, for the supply of New York in America, 

 from a source nearly forty miles distant, at a cost of £2,500,000, and which 

 yields a daily supply of about 30,000,000 gallons a day, was one of the first 

 large works on this system. The Cochituate Works, for the supply of Bos- 

 ton, United States, are of more recent date. They supply about 7,000,000 

 gallons per day to 140,000 persons. The distance is twenty miles, and the 

 cost has been about £1,500,000. The GorbalsWater Works, as they are 

 now completed, receive their supplies from a tract of elevated ground of 

 2750 acres in extent, furnishing the city of Glasgow and its neighbourhood 

 south of the Clyde with about 4-,000,000 gallons of good water per day, be- 

 sides a stipulated compensation to the stream of 1,310,712 gallons. The 

 annual rain is about 45 inches on the average, and the capacity of the re- 

 servoirs equal to 61,000 cubic feet for each acre of collecting ground. 



The Liverpool Water- Works, now nearly completed, in the neighbourhood 

 of the hills known by the name of Rivington Pike, near Chorley, will collect 

 the water from about 10,000 acres of hilly ground, and are estimated to be 

 capable of affording a supply of from 12,000,000 to 15,000,000 gallons of 

 water per day, after giving about half that quantity as compensation to mills. 

 The rain is about 57 inches on the average, and the capacity of the reservoirs 

 about 49,000 cubic feet per acre of collecting ground. 



The Manchester Water- Works, which are now all but completed, and 

 which have supplied Manchester for nearly five years, collect the water from 

 about 19,000 acres of mountain ground, and are calculated to afford, when 

 finished, about 25,000,000 gallons per day to Manchester and its neigh- 

 bourhood, besides giving 17,000,000 as compensation to the mills on the 

 river upon which the works are constructed. The average rain is a little 

 above 50 inches ; the total storage upwards of 600,000,000 cubic feet, or 

 about 34,000 cubic feet per acre. Much water runs to waste for want of 

 sufficient storage. 



The supplies to Sheffield, Newcastle-upon-Tyne, Halifax, Blackburn, Bol- 

 ton, Bristol, Edinburgh, and most of the large towns and cities in the manufac- 

 turing districts, and in the north of England and Scotland, are supplied in the 

 same manner ; but it would be tedious and needless to describe the peculiari- 

 ties at each place. 



There is, however, one point in connexion with the supplies obtained in 

 this way which should not be passed over. Water obtained from gathering 

 grounds is occasionally, sometimes frequently, discoloured in times of heavy 

 rain, and is rendered unfit for immediate supply to the inhabitants of a town. 

 Various methods have been adopted for obviating this objection. In some 

 cases the discoloration from peat or other causes is so great, that no 

 means which can be practically adopted on a large scale have been suffi- 

 cient to clarify or purify the water to such an extent as could be desired. 



In many works a system of clarification has been adopted by means of a 

 succession of reservoirs, in which the water is allowed time to deposit impu- 

 rities, being gradually decanted off from one to another, until it at last becomes 

 fitted for consumption. In others, mechanical filtration has been applied, 

 the water being passed through layers of fine sand ; but no mechanical filtra- 

 tion will effectually remove the stain of peat. 



