mile. Plate XVI. is a view of the work at Jewell's Brook. The culvert for the stream is 6 feet span and 148 feet long. The larger culvert for a private road is 14 feet span and 141 feet long. The wall which supports the Aqueduct at this valley is 50 feet high. In this case, as in many others, the slope wall which covers the face of the embankment has an arch turned in it over the top of the culverts : the object of this is to N S& ^ S3 %l 3 b 9 © © to} U-l ^ 105 prevent the direct pressure of the wall upon the top of the parapet wall, as it would tend to displace the coping or in- jure the parapet itself. After crossing Jewell's Brook the Aqueduct passes along the bank of the Hudson through the village of Dobb's Ferry, where there is a tunnel and a valley requiring a culvert, and continues from this place to the village of Hastings, where there is an Aqueduct bridge over a rail-road which is used for transporting marble from the quarry near by, to the land- ing on the Hudson River. Plate XVII. is a view of this bridge and the view under the arch shows the face of the quarry which is near the work ; the landing at the river is near by, giving a very rapid descent from the quarry. The arch has a span of 16 feet and a rise of 1^ foot. This bridge is twenty-one miles from the dam. From Hastings the Aqueduct continues along the bank of the Hudson until it reaches the village of Yonkers where it leaves the valley of the Hudson, and passing through a tun- nel of considerable length reaches the valley of Saw-Mill River. At the crossing of this valley there is a culvert of 20 feet span for a public road to pass under the Aqueduct, and one having two arches each 25 feet span for the river. Plate XVIII. is a view of the work at Saw Mill River. The water is set back at this place by a dam for a mill a short distance below, giving the stream an appearance of more magnitude than it really possesses. This point is 25 miles from the dam. The wall which supports the Aque- duct over this valley is 40 feet high. From Saw-Mill River the Aqueduct passing through one 27 106 tunnel soon reaches Tibbit's Brook, which it crosses by means of a foundation wall about 30 feet high and a culvert of 6 feet span, and continues along the south side of the valley of this brook, thence to the Harlem River which it crosses at one mile from Mc'Comb's Dam. This crossing is thirty-three miles from the Croton Dam, and about ten miles from the City-Hall. The distance across this valley is about a quarter of a mile, and the surface of the River is 120 feet below the bottom of the Aqueduct. In all the examinations which were made with a view of bringing water from Westchester County, the crossing of this River, or arm of the sea, was regarded as the most formidable work that would be encountered ; various plans were proposed, and in presenting these plans the project was such as to call into requisition much talent and skill. An Aqueduct Bridge built of stone, having arches resting upon piers and abutments, was proposed so as to continue the Aqueduct across with its regular inclination. An Inverted Syphon of iron pipes was proposed ; the pipes to descend to a level near the surface of the River, and passing along upon a stone embankment rise again and connect with the Aqueduct : in this stone embankment an arch was to be built of sufficient dimensions to allow free passage of the water of the River. Another plan was proposed which, though novel in its application to such purpose, was worthy of consideration : this was to build a Suspension Bridge of wire cables reach- ing across the valley, supported at intervals upon suitable stone piers. This, maintaining the regular inclination of nii RW a P H e 107 the Aqueduct, would support iron pipes. The design was a bold one, yet instances where such bridges have been con- structed for road-ways afford examples of the feasibility and permanency of the structures, and prove that the application of that principle for this purpose was riot a visionary project. The plan which was adopted as the most suitable under all the considerations of economy and security to the work, was a Low Bridge to support an inverted syphon of iron pipes ; and the design of it was as follows : adjacent to the