Walks are formed about the work bordered with grass, giving a neatness and finished appearance to the whole; and every thing in connection seems to indicate that the vicinity of the _Croton Dam_ will be one of the resorts in summer seasons for the citizens of New-York. From the Croton Dam the Aqueduct passes along the left side of the valley of the Croton River until at the mouth of this river it reaches the left bank of the Hudson, which it pursues, keeping at a distance of nearly half a mile from the River, until it arrives at the village of Sing-Sing, which is eight miles from the dam. In the course of this distance the Aqueduct passes through four tunnels and encounters many valleys and ravines where high foundation walls were required, and culverts for the passage of the streams. At the village of Sing-Sing there are two Aqueduct bridges; one over a public road-way, and the other over the Sing-Sing Kill. These bridges and the adjacent work form a very interesting point on the line of Aqueduct. Plate XII. is a view of the Aqueduct at this place: at the left of the picture may be seen the bridge over the road, and on the right that over the Kill. The bridge over the road has a span of 20 feet, and the direction of the road-way being not at right angles with the line of Aqueduct required the arch to be built askew; the arch lies in the direction of the road-way, having the ends in planes parallel with the direction of the Aqueduct. This bridge is worthy of notice, but public attention is more generally directed to the larger one: _that_ has an arch of 88 feet span and a rise of 33 feet; the form of the arch is elliptical, being a compound curve drawn from five different centres, or radius points. The Kill, or valley over which this arch stands, is a deep narrow gorge worn by a small stream which empties into the Hudson River. The bottom of the ravine is about 70 feet below the soffit or under side of the arch. Plate XIII. is another view of the large arch taken from the bottom of the valley near it, and shows the bridge which has been constructed for a public road passing under it, and the mill near by. [Illustration: XIII F. B. Tower. Napoleon Gimbrede. sc. AQUEDUCT BRIDGE AT SING SING.]