Three plans were suggested : an open canal, an arched brick tunnel, and iron pipes. The first is condemned, because of the impurities, which, in its course it would be liable to gather ; and upon the whole, the preference is given to the arched tunnel, which, according to an estimate of Canvass White, might be constructed, of five feet diameter, for $31,174 per mile, making the whole cost, from the point where the water was taken from the Bronx to Macomb's dam, $400,000. Independently of superior cheapness, as compared with iron pipes, a tunnel of the size proposed, would supply the greatest quantity of water that could be required.

But in all these plans, the water was to be forced up by machinery at the Harlem river, to the height requisite to its introduction, with a sufficient head into the city. The tide water of the Harlem river, was relied upon for the power, and the cost of the bridge and dam, to raise and pass the water, was estimated at $50,000. The machinery for lifting, and the reservoirs on Harlem heights, which were to be 120 feet above tide, were to cost $50,000 more. And the three lines of twelve inch iron pipe, calculated to convey 2,000,000 gallons daily (an adequate supply for the then population), were to cost $10,000

MEMOIR OF THE per mile each. The distance from the receiving reservoir at Harlem to that at Thirteenth-street, being four miles, the whole cost of the pipes would be $120,000.