ON THE SUPPLY OF WATER TO TOWNS. 77 



In most gathering grounds the water is at times perfectly pure, and a very- 

 large portion of that which flows off the ground is in the most unexcep- 

 tionable condition for immediate consumption. If this were mixed with 

 that wliich had been previously stored in a discoloured state, the whole 

 might be spoiled, and deposition or filtration would have to be resorted to. 



Taking advantage of these circumstances, a system of separation has been 

 adopted in many works, and in the largest and most complete manner in 

 those for the supply of Manchester. There, by simple self-acting means, not 

 liable to any derangement, each stream subject to discoloration is made to 

 separate itself, the pure uncoloured water either flowing direct to Manchester 

 or to reservoirs set apart for the storage of pure water. The turbid water 

 flows to other reservoirs, where it either bleaches and settles for subsequent 

 use, or is employed in aflbrding the required quantity of compensation water 

 to the mills on the stream. This system is probably the simplest, cheapest, 

 and most eff'ective which has been suggested ; and though only recently 

 introduced, is becoming very general, where circumstances are favourable 

 for its adoption. 



5. The supply from natural lakes. — This supply can scarcely be said to 

 differ from that of gathering grounds and large storage reservoirs, but there 

 are one or two peculiarities which it may be desirable to allude to. 



Its simplicity, where it can be adopted, is a material recommendation. It 

 saves the construction of large artificial reservoirs, which is sometimes one of 

 the most difficult works that an engineer can undertake. The great depth, 

 and frequently the large surface, of water which is exposed, in comparison 

 with the collecting area, favour the clarification of the water, and, as lakes 

 are generally found in mountainous districts and in the harder geological 

 measures, the water is frequently of the very purest quality. The towns of 

 Whitehaven and Dumfries are supplied with water from natural lakes ; the 

 first from Ennerdale Lake in Cumberland, and the latter from Loch Rutton 

 in Dumfriesshire. The town of Inverness is also supplied from lake water, 

 the water being taken from the river Ness, a few miles below Loch Ness. 

 But the largest work of this kind when completed will be the supply to the 

 city of Glasgow with water from Loch Katrine, a work for which parlia- 

 mentary sanction has been obtained, and which is now being carried out. 

 The distance is about thirty-four miles, and the supply to the city will be 

 50,000,000 gallons per day. 



Objections have been taken to the quality of these mountain lake waters 

 on account of their excessive purity and their violent action upon new lead 

 under certain circumstances. Similar objections were urged to the supply of 

 very soft and excellent water to the cities of New York, Philadelphia and 

 Boston in the United States, but experience has shown that no practical evil 

 has resulted, either in that country or in this, from the passage of such water 

 through leaden service pipes in any town's supply of water. 



The supply of water in the towns of Inverness and Whitehaven, both of 

 which are supplied with water of the greatest softness and the utmost purity, 

 almost equal in all respects to distilled water, are striking instances of the 

 safety with which such water can be conveyed to the inhabitants through 

 leaden pipes and cisterns. Inverness has been supplied with Loch Ness water 

 for upwards of five-and-twenty years, through the intervention of lead pipes and 

 cisterns, without a single case of illness ever having occurred which could be 

 attributed in the slightest degree to the contamination of the water by lead. 



In Whitehaven the water was introduced from Ennerdale Lake in the 

 summer of 1850. This water is of the same degree of purity and softness as 



