The timber bridges developed the steel truss bridge, the typically American construction, of to-day. In an earlier day the timber bridges were the glory of the engineer. Sometimes you see one of these old fellows remaining, like the long structure that Mr. Walcott built across the Connecticut River at Springfield, Mass., in 1805, and which still does good service; but the most of them have passed away. Fire has been their most persistent enemy. Within the past two years fire destroyed the staunch toll-bridge at Waterford on the Hudson, just above Troy. The bridge was a faithful carrier for one hundred and four years. In many ways it was typical of those first constructions. It consisted of four clear arch spans--one 154 feet, another 161 feet, the third 176 feet, and the fourth 180 feet in length. It was built of yellow pine, wonderfully hewn and fitted, hung upon solid pegs; and save for the renewal of some of the arch footings, the roof, and the side coverings, it was unchanged through all the years--even though the heavy trolley-cars of a through interurban line were finally turned upon it. About the same time, the once-famed Permanent Bridge across the Schuylkill River at Philadelphia was built. It had two arches of 150 feet each and one of 195 feet. In its day it was regarded as nothing less than a triumph. A very old publication says: "The plan was furnished by Mr. Timothy Palmer, of Newburyport, Mass., a self-taught architect. He brought with him five workmen from New England. They at once evinced superior intelligence and adroitness in a business which was found to be a peculiar art, acquired by habits not promptly gained by even good workmen in other branches of framing in wood.... The frame is a masterly piece of workmanship, combining in its principles that of king-post and braces or trusses with those of a stone arch." In after years, the Permanent Bridge was also entrusted with the carrying of a railroad. It has, however, disappeared these many years.