verts, and reservoirs, required to deliver the water on a declivity of fifteen inches to the mile, to a receiving reservoir on the high grounds near Harlem river, and from thence across said river to another reservoir of sufficient elevation, near Manhattan ville, (should he be of opinion that these reservoirs will be necessary,) then to a distributing reservoir three or four miles from the City Hall, near Thirty-eighth-street and the Fifth Avenue, preserving an elevation of 117 to 120 feet above tide at said reservoir; but if any of the reservoirs named can be dispensed with, or if additional ones be required, to report the reasons why, and to conform the estimate to the alterations in the plan, should any be commended to furnish a report in writing, with a profile and map of the survey, show- :

ing the water line of the basin formed by the dam the land that Avill be overflowed on ;

both sides of the river the line traced for the aqueduct the depth of excavations and the ; ;

MEMOIR OF THE

height of embankments, &c., in order that a plain and comprehensive view of the whole subject may be given. To ascertain whether the cost of erecting a high dam, at or near Garretson's mill, and the consequent damage that will accrue by the overflowing of the land and injuring mill privileges, will be greater than the cost of taking the water from a higher source up the river. The Commissioners have also employed George W. Cartwright, Esq., a civil engineer, residing at the village of Sing Sing, and who possesses much local knowledge of the Croton and its vicinity, to run levels on both sides of said river, starting from Garretson's mill, at aheight of thirty-eight feet, and carrying his levels up until they loose themselves at the surface of the water, in order to ascertain what quantity of land would be overflowed with water by the erection of a high dam at the aforesaid station.