Constantinople presents remains of the skill possessed by the Romans in the numerous subterraneous reservoirs, covered with stone arcades supported by pillars. Pont du Gard is another relict that supplied the town of Nismes, France. “It consists of 3 tiers of arches, the lowest of 6 arches, supporting 11 of equal span in the center tier, surmounted by 35 of smaller size. Its height is 180 feet, the channel way being 5 feet high by 10 feet wide; the capacity was estimated at 14 million gallons per day.” In Mexico and Peru are found water channels of marvelous length, while India is noted for the numerous impounding reservoirs of wonderful dimensions,--the Poniary reservoir, having an area of 50,000 acres, and banks 50 miles in extent. While the ancients have left monuments of their skill in gathering and conducting waters, modern science has been, and is, endeavoring to leave a reputation for its devotion to the knowledge of pollution in, and purification of waters required for mankind. The vast amount of literature devoted to this subject, containing a varied scope of discussions, arguments and analyses, has a tendency to lead one to the conclusion that wholesome water scarcely exists. In fact, the theory advanced by the Massachusetts State Board of Health, in their Fifth Annual Report, is not so premature. They say: “The time may come when it will be necessary to supply our drinking water from sedulously guarded but limited sources of supply, and to furnish for manufacturing and other uses less pure water. This plan is partly carried out in Paris, and it is the purpose to enlarge it, although much of the water is unfit to drink. “The injurious character of a water, impregnated with sewage matter, might not be discovered for years. You might go on using it for years and might not be discovered, and you might have some outbreak of disease in the place, which nevertheless might be connected with the use of that sewage water.” The Rivers Pollution Commission of Great Britain struggled with this subject for six years, and at last resolved upon the following classification of potable waters: { 1. Spring water. } Wholesome, { 2. Deep well water. } very palatable. { 3. Upland surface water. } { 4. Stored rain water. } moderately Suspicious, { 5. Surface water from cultivated lands. } palatable. { 6. River water to which sewage gains } Dangerous, { access. } palatable. { 7. Shallow well water. }