water line is 60 feet to the spring of the arches, and 95 feet above the lowest foundation that has been put down ; the arehes are semicircular, and the height 100 feet to the soffit. or under side, at crown to the top of the parapets 114 feet above the ordinary high water line of the river, and 149 feet above the lowest foundation of the piers that have been commenced. The width across, on the top of the parapets, is 21 feet the exterior ;

of piers, spandrels and parapets has a bevel of 1 to 48, and have openings in the interior walls. The space between the parapets is arranged to receive and protect from frost two cast iron pipes, each four feet in diameter, which are to lie 12 feet below the grade line of the aqueduct, to which they will descend from the gate chambers at the ends of the bridge. The object of using pipes in this case, is, more effectually to secure the conduit from leakage, that might eventually injure the masonry of the bridge, and it incidentally allows the bridge to be constructed of less height. To make the capacity of the pipes for conveying water equal to that of the aqueduct, an extra fall of two feet has been given across the bridge, and the aqueduct on the southern side of the river is constructed two feet lower than the regular grade, to accommodate this arrangement. It is intended in the first place to put down pipes 3 feet in diameter, and to increase the size as the wants of the city may require. The foundations of all the land piers but two have been put down, with bearing piles to support them they are placed below high water line and 5 to 6 of the base courses ; ;