Illustrations of the Croton Aqueduct

by F. B. Tower

In the alternative to which they were driven by the Act of the Legislature, the plan of an Aqueduct bridge of masonry was adopted as the proper one for crossing the River; but in establishing its altitude they complied only with the requisitions of the law, and made the soffit or under side of the arches at the crown, 100 feet above common high water level. This would not carry the work up to the level of the Aqueduct, and would render it necessary to connect the Aqueduct on each side of the valley by iron pipes which would descend to the level of the bridge and crossing it rise again to the masonry channel-way. The plans which were before spoken of for a bridge of masonry across this valley, contemplated a structure which would maintain the regular inclination of the Aqueduct; and the channel-way would have been formed of masonry having a cast iron lining; but a more full consideration of the subject suggested the propriety of using iron pipes over the bridge, even if it had been carried up to the grade plane of the Aqueduct: when the use of iron pipes was determined upon, then considerations of economy induced them to build the work only high enough to comply with the requirements of the law.

The plan which has been adopted for building an Aqueduct bridge across this valley is as follows: on the south shore of the river there is one arch of 50 feet span, across the river there are eight arches, each of 80 feet span, and on the north shore there are six arches each of 50 feet span; making a range of fifteen arches. From the extremes of this range of arches, a foundation wall of dry stone work connects with the Aqueduct.

Two of the piers in the river have a rock foundation and the foundations for those where rock is not obtained is formed by driving piles which are placed 2½ feet from centre to centre, and the spaces between filled with concrete to a depth of 3 feet below the top of them.

[Plate XIX]. is a view of this bridge, which, when completed, will be the most interesting work on the whole line of Aqueduct, and in its appearance will rival the grandeur of similar works of the Ancient Romans. The height from the foundations in the river, to the top of the work is 150 feet; the width across the top is 21 feet. The pipes when laid upon the bridge will be covered with earth to protect them from frost. The distance between the extremes of the pipes when laid across the bridge will be 1377⅓ feet. For a distance of 18 feet at each end of the pipes there is an inclination and the remainder of the distance across, which is 1341⅓ feet, they are level.

The bottom of the interior of the pipes on the level part, is 12-8/10 feet below the bottom of water way of the Aqueduct on the north side, and 10-5/10 below that on the south side of the valley.

In the progress of excavating in one of the coffer dams in the channel of the river a portion of a sunken vessel was found within the enclosure; it had the appearance of great age. Tradition among the inhabitants of the vicinity says that at an early period of the Revolutionary war a vessel was scuttled and sunk in that part of the river.

XIX

F. B. Tower.

Napoleon Gimbrede. sc.