490 



UNITED STATES. 



On the execution of this branch of the work com- 

 mitted to their care, the board of managers rely with 

 the fullest confidence, and do not hesitate to pro* 

 nounce it as solid and complete a piece of masonry, as 

 is any where to be found in the United States. 



The superstructure consists of five arches, or five 

 setts, or series of arches, each composed of five sec- 

 tions or ribs^ as they are usually called, and rising 

 from the choi^d line, in the proportion of 13 feet in 

 100. These sections or ribs, are formed of white 

 pine plank, of from thirty-five to fifty feet in length, 

 four inches thick, and twelve inches wide (except 

 the middle section which is thirteen), and repeated 

 one over the other, breaking joints, until they form a 

 depth of three feet through. This mode of construct* 

 ing wooden arches, is considered as a great improve- 

 ment in bridge architecture, 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 re- 

 lative situation of these sections is such as to leave 

 two openings of eleven feet each in the centre for 

 carriages, and two of four feet six 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 con- 

 vexity and depth, are placed, which, inclining to- 

 wards 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 



