in 1805 because by the end of the year Owen Biddle had roofed and sided the structure, creating America’s first documented “covered bridge.” (Encore Editions)
Birch’s etching, shown in the foreground along the shore and reproduced here, reveals the bridge after it was covered. (American Philosophical Society)
In Judge Peters’ letter to the board, he made the following argument. “From the time of the first idea of a wooden superstructure, I have never wavered in my opinion of the indispensable necessity of the cover.” Pointing out that covering the exposed timbers with paint, some other coating, or even with lead sheets leads to cracking, rotting, and feculation, he asserted that “Nothing has been proved so effectual, as covering the whole of a frame, constructed of large timber, with a roof; and, at the sides, excluding rain, without preventing an uninterrupted circulation of air” (1815: 46). Aware of the famous Schaaffhaűsen [also spelled Schauffhausen and Schaffhausen] bridge in Switzerland, he wrote: “It had been by its cover, effectually preserved from decay for thirty-eight years, and was perfectly sound, at the time the French [by Napoleon’s troops in 1799] destroyed it” (p. 47). He then quotes Palmer’s letter at length. Peters had earlier assumed the Board would agree to a cover and had already sketched plans for it, three of them submitted individually by Mr Dorsey, Mr Traquair, and Mr Owen Biddle.
At last the board relented and agreed to proceed, based on Peters’ estimate of $8,000. But first Peters also had to argue for the work being done immediately because some thought the wood might better age in the open for a year or so. Owen Biddle, one of the young nation’s premier builders and author of a handbook entitled The Young Carpenter’s Assistant; or A System of Architecture Adapted to the Style of Building in the United States, published in 1805, completed the work within the year. Wrote Peters: “It was executed with singular fidelity and credit, by Mr. Owen Biddle, an ingenious carpenter and architect of Philadelphia. . . .” (p. 27). Indeed, Biddle’s work gave the bridge an elegant appearance, with the lower arched portion not just painted to look like a stone arch with stone blocks above but with stone dust embedded into the paint. The upper portion consisted of vertical colonnades and twenty-two windows with shutters on each side.
The builders also carried out two other apparent innovations. For protection, they installed lightning rods along the roof, a technology whose invention is attributed to Benjamin Franklin in 1749 following his (in)famous experiment with a kite and a key. Later, to keep the decking boards from being worn, they installed planks lengthwise to carry the wheels of most carriages and wagons in addition to planks along the trusses to keep vehicles from damaging them. Peters also requested that William Rush, a prominent Philadelphia sculptor, be commissioned to create pediments at each end, the eastern one celebrating commerce and the western one agriculture. Finally, the company had “a pyramidical Pedestal, surmounted with four Dials, for the benefit of passengers,” which was an obelisk, erected at the eastern end celebrating those who erected the bridge, listing its vital statistics, and telling the story of the heroic efforts to erect the two piers (pp. 77–80).
Covered Bridges for a New Nation
Judge Richard Peters, President of the Board that built the Permanent Bridge, the first documented covered bridge in the United States, had not created the idea of preserving a wooden superstructure with roof and siding, but he appears to have been the first to persuade builders to actually cover a bridge. The Permanent Bridge is not just well documented but was seen and noted by virtually all of the many travelers who later published descriptions of their travels around Philadelphia. Although an iconic structure and the most perfect of Palmer’s many bridges, the Permanent Bridge had to be replaced in 1850, by which time bridge technology had advanced dramatically. By then, a bridge capable of carrying railroad trains as well as pedestrians and carriages was required, but building covered bridges such as this first had to become routine.
As noted earlier, Charles Willson Peale, writing in 1797, alleged that there were already covered bridges in the United States: “It has been advised to make roofs to cover Bridges, and some are so constructed in America.” But there is no known documentation of any actual bridges so covered. Peale’s statement implies that somewhere, perhaps in some smaller towns far from the cities, there were a few covered spans lurking. But it must be borne in mind that we are attempting to reconstruct a complete jigsaw puzzle with only a small percentage of the pieces. There is a likelihood that wooden trusses had developed as early as the 1760s. We know that the idea of covering bridges was known, both from Robert Smith’s statement in 1769 and the drawing in The Columbian Magazine from 1787. These ideas cannot have come from nowhere. It was also difficult for any one writer to know about distant areas, and in those days “distant” could have been a mere thirty miles depending on the existence of passable roads. There is ample documentation of the great bridges of the period, but it is unlikely that every bridge was noted.
After Palmer’s Permanent Bridge over the Schuylkill in Philadelphia was gutted by a fire in 1850, a replacement that added a rail line was built, but this was completely destroyed by fire in 1875. Shown is the third bridge on the site, a three-span massively arched Burr truss that lasted from 1875 to 1888 when it was replaced by an iron cantilever bridge. (Wikipedia Commons)
The populations of New England and Pennsylvania were very limited and infrastructure barely existed. Even in 1837, as described earlier by Englishman Robert Stevenson, America’s road system was deplorable, though New England’s was somewhat better. Nonetheless, before 1800, even in New England the road system was minimal. Neither federal nor state governments were building infrastructure at the time. Bridges, like roads, had to be built by private investors who contributed capital towards an enterprise that hopefully would pay a dividend through the tolls collected. Because there would be no incentive for a company to build a modest bridge on a back road—since users there could easily avoid tolls by crossing the stream in the usual way, by fording—the principal bridges being built were over major bodies of water and often of dramatic dimensions. It seems likely that most, if not all, of these larger bridges have been documented. Indeed, most were by Timothy Palmer himself, who affirms that none of his earlier bridges were covered (though some were retrofitted with covers after 1805). How would Peale know there were covered bridges elsewhere? Unless he had seen them with his own eyes, we must ask where were they? Possibly he had seen the drawing in The Columbian Magazine of January 1787. Perhaps he had heard of covered bridges in Europe and thought they were in the United States. However authoritative his statement may sound, there is no corroborating evidence. Thus, Palmer’s 1805 Permanent Bridge retains the title of “first covered bridge” until there is hard evidence showing otherwise.
This milestone, however, important as it is, privileges the least significant of Palmer’s innovations. Everything else about this bridge and the ones preceding it built by Palmer and the two Spoffords demonstrate the real progress made in American bridge design: the development of deep-water pier construction, the rapid evolution of timber bridge trusses, and the ability to construct massive spans of exceptional length and strength. After this, successive builders created ever more innovations in truss design, and America’s first professional engineers developed the science of stress analysis, making bridges ever more rational and efficient. Their story will be told in Chapter 2.
More Remarkable Bridges: Theodore Burr and Lewis Wernwag
After knowledge of Palmer’s Permanent Bridge spread, the idea of covering a wooden truss bridge to protect it from the weather was no longer considered odd or controversial. Covered bridges soon became the norm and continued to be so until the building of timber truss bridges was phased out during the late nineteenth and early twentieth centuries. The essence of covered bridges, then, is what the roofs and siding protect—trusses and other construction features. This vast subject will be treated systematically in
