From the testimony of a number of reputable physicians, before the Rivers Pollution Commission, of 1874, hard water, to a limited extent, ten degrees, was not considered injurious, and, by some, absolutely beneficial to health, although soft water, for a general water supply, was preferable. Mr. Homersham, C. E., the designer of several of these works, testified, before this commission, that it cost £1, 7s. for precipitating 1,000,000 gallons. To introduce this system into London, with a consumption of 100,000,000 daily, the cost, he says, would be $3,000,000 for plant, and requiring over thirty-three acres of ground for basins, etc. The relative sanitary condition of cities, in the United Kingdom, using hard and soft water, is shown in the following table: AVERAGE CHARACTER AVERAGE RATE NO. OF TOWNS. POPULATION. OF WATER. OF MORTALITY PER 10,000. 26 73,366 Not exceeding 5° 29.1 25 81,655 Above 5°, but not 28.3 exceeding 10° 60 44,797 Above 10° 24.3 London 3,254,260 From 16° to 32° 24.6 The celebrated engineer, Mr. Bateman, of England, estimates the saving to Glasgow, by soft water, at $180,000 per annum; and if London used the same character of water, the equivalent would be $2,000,000 annually. The use of lime, by private consumers, is recommended by the trustees of the water department of Columbus, O. They say that one ounce of lime, when added to thirty-six gallons of water, make it superior, for washing purposes, to the rain-water usually obtained from the cistern. CHAPTER IV. SYSTEM OF SUPPLY. The systems of supply may be arranged under three general heads, viz: 1st. By springs and wells. 2d. By gravitation. 3d. By pumping. SPRINGS AND WELLS. We have, under this name, nature’s resources for supplying our wants, whose facilities for furnishing the requisite supply depend upon the local rain-fall, configuration of the land, and the nature, or geological formation, of surface and subsoils. Land springs are fed by rain-water, gravitating through loose permeable soils. The waters are very readily affected by infiltration of surrounding soils, and their course so easily changed in any direction that the permanence of such a source can not be relied upon.