At 8 miles from the Croton dam, it reaches the village of Sing Sing, and continues south through the villages of Tarrytown, Dobbs' Ferry, Hastings, and Yonkers. At the latter place, it leaves the bank of the Hudson, crosses the valleys of Sawmill river and Tibbits' brook, thence along the side of the ridge that bounds the southerly side of Tibbits' brook valley, to within 34 miles of the Harlem river, where the high grounds of the Hudson fall away so much as to require the aqueduct to occupy the summit of the country lying between the Hudson and East rivers. This formation of country continues to, and is terminated by, the Harlem river, at the point where the aqueduct intersects it, which is one mile northwesterly from Macombs' dam.. The length of the aqueduct from the Croton dam to Harlem river, is 32.88 miles, for which distance it is an uninterrupted conduit of hydraulic stone and brick masonry. The high ground that bounds the northerly side of the Harlem river valley, is very near the level of the aqueduct at that place and the width of the valley at the aqueduct level ;

is about 1450 feet, or a little over one quarter of a mile over which a bridge is designed ;

to be constructed (and is now in progress) at an elevation of 114 feet above the level of high tide in the Harlem river, on which iron pipes are to be laid to convey the water across the valley. The shore on the southerly side of the river is a bold, precipitous rock, rising at an angle of about 30 degrees, to a height of 220 feet, or about 100 feet above the level of the bottom of the aqueduct. After crossing this valley, the aqueduct of masonry is resumed, and continued 2.015 miles, to the termination of the high ground on the north side of Manhattan valley.