The span between the Pennsylvania abutment and the first pier, as well as between each of the other piers, is 194 feet; and from the New Jersey abutment to the first pier, the span is 156 feet, leaving a water way of 932 feet, out of 1100, the distance across the river from the top of one bank to the other.
The piers are all carried up with cut stone, in courses of range work, varying in depth as they proceed upwards, from 25 to 28 inches, until they rise to the top course, which is 12 inches, the sides and lower end battering 1 an inch in the foot; these stones extend into the body of the work, from 3 inches to 5 feet. The exterior or cut stone, as high as the water has ever teen known to rise, is laid in terras mortar ; and throughout the whole extent, lengthwise, every second or third course is clamped together with iron clamps. Crosswise also of the piers, every third or fourth course, eight or more iron cramps are extended from side to side, and let into The courses of cut stone. These, together with a vast number ckf branch cramps, it is presumed will effectually secure the whole from spreading or giving way in any direction. The ends of the piers, up stream, are semicircular, and after rising 41 feet from their foundations, with the usual batter of the sides, they recede or batter at an angle of 67°, until they rise to the further height of 10 feet perpendi cular, when they are again carried up with the for mer batter to the square, where they terminate, and receive their finish with a coping of cut stone, in the form of a Ilia dome. The stones of which this angular part is composed, are all deep in their bed, extending from 2 to 5 feet into the pier, and are each secured with a clamp of iron. At this point the cut stone ceases, and the dimensions of the pier are here 62 feet in length, and 20 feet in breadth.
An offset of 8 inches is then made on the sides, and the square part of the piers again carried up, with a skew back, to the further height of 3 feet 9 inches. The feet of the arches rest on this offset and spring from this angle. The height of the piers next the shores, from the foot of the arches to ordi nary low water mark, is 27 feet 5 inches, and of those in the middle, 28 feet 7 inches each. The distance between the abutments is 1008 feet, and the whole length of the bridge, including the wing walls, is one quarter of a mile.
The whole of the stone work done consists of 169,223 feet of cut stone, contained in 16,650 perches of masonry.
The superstructure consists of five arches, or five sets or series of arches, each composed of five sec tions or ribs, as they are usually called, and rising from the chord line, in the proportion of 13 feet in 100. These sections or ribs are formed of white pine plank, of from 35 to 50 feet in length, 4 inches thick, and 12 wide (except the middle section, which is 13), and repeated one over the other, break ing joints, until they form a depth of three feet through. This mode of constructing wooden arches is considered as a great improvement in bridge ar chitecture, and we have reason to believe was first introduced into practice by Mr. Burr, the architect
of this bridge. Be this as it may, it is supposed to possess many advantages over those formed of solid and massy pieces of timber. The relative situation of these sections is such as to leave two openings of II feet each, in the centre, for carriages, and two of 4 feet 6 inches each, on the sides, for foot walks. The general width of the bridge is therefore 36 feet from out to out, and the travelling ways will be on the chord line between these sections. Outside of the two exterior sections, wing arches of 50 feet in length, and of the same convexity and depth, are placed, which, inclining towards the centre, are united to these sections, and securely bolted through them. This gives the bridge an additional base of 16 feet, and a bearing of 52 feet on each pier. On the top or circumference of these sections and wing arches, beams or ties and diagonal braces are laid and let into each other, in the form of lattice work, and the whole firmly connected with the arches, by iron bolts with screws going through them at the distance of every eight feet: thus they are made to form one entire connected arch, which can neither admit of any sideway or intestine motion between the sections, nor be readily injured or endangered by high winds.
The platform on which the travelling is per formed, is suspended from these arches, by means of iron chains or links, which hook into the eye bolts, firmly fixed through the arches, at the dis tance, also, of every 8 feet in the three middle sec tions, and 16 feet in the two exterior ones. To the lower ends of these chains is appended a stirrup, in which the beams lay which sustain the joists and flooring. To prevent the platform from having any swinging motion, wing chords and diagonal braces are again interposed, which effectually perform this service.
The expansion of the arches (were not the so lidity and weight of the piers and abutments of themselves sufficient) is completely guarded against by the intervention of wooden chords which em brace and connect the several feet of these arches together. These serve also a further important pur pose, to wit, of stiffening and strengthening the arches, by means of upright bracing, which takes place between them and the chords; so that by the application of great weights, to either end of the arch, no vibratory motion can ensue, as the press ure is by this means distributed throughout the whole extent of the segment.
The three great objects, convenience of travelling, strength, and durability, are all happily united in the model adopted, nor has ornament been wholly thrown aside. The access to the bridge on either side, and throughout the whole extent of the plat form, presents to the traveller a plane without any sensible rising.—The bridge was finished in the month of February 1806.—Extracted front Mease's lf"onders of Nature and ./Irt.