America's Covered Bridges. Ronald G. Knapp

for the main span collapsed eight years later, on August 28, 1801, under the weight of a livestock drive. Asa Town replaced it with a bridge of three framed arches, but an ice jam destroyed most of the bridge in 1807, and the crossing was not rebuilt until some thirty years afterwards.

      The following year, 1794, saw the construction of two more remarkable bridges. The lesser known Piscataqua Bridge, seven miles north of Portsmouth, New Hampshire, consisted of a hundred short spans on pile and trestle piers but having a “stupendous arc” span of 244 feet over the navigable channel of Great Bay. Considering that the builders included Timothy Palmer, we can surmise that the arched span resembled those built earlier, but its length, if correct, would be remarkable and unprecedented. If correct, then Palmer’s span approached the bold dimensions of some bridges proposed but not built by Pope and Peale.

      The bridge from Haverhill to Bradford, Massachusetts, over the Merrimack is probably the best understood of Palmer’s great bridges since it lasted until 1875 when it finally had to be demolished. Although there are numerous photos of the structure taken long after it had been covered, according to Timothy Dwight, President of Yale University and author of Travels in New-England and New-York (1821–2) who visited the bridge twice, in 1796 and 1812, the bridge underwent considerable “rebuilding” or “remodeling” in 1808 and 1825, the earlier one supervised by Palmer himself. Because the piers were so massive, each containing 4,500 tons of stone, it is unlikely the remodeling changed the span lengths, each of the three being 182 feet. In addition, the bridge was double lane, each lane being 15.5 feet wide, and the arch, located beneath the trusses, rose 8 feet. Wright related that Palmer, along with co-builder Moody Spofford, first demonstrated the bridge’s strength with a 10-foot model that allegedly held eleven men weighing together 1,600 pounds. Between the Bradford shore and the third span stood a 30-foot drawbridge. Dwight reports that decay had set in by 1812 on his second visit, and that the arches had been removed. Since he does not mention the bridge as now covered, we presume that covering came later, perhaps as late as 1825. Surviving photos, however, show that the arches had been restored and an uncovered walkway added. That Palmer and Spofford could have built such a magnificent bridge with such great spans in 1794 demonstrates how advanced bridge building had become by that time.

      Although there are photographs of the Rocks Village Bridge over the Merrimack between West Newbury and East Haverhill, these include the 1828 Town lattice replacements for two of the original six built by Palmer and Moody Spofford in 1795 and partially rebuilt by them around 1812. The original bridge, which opened on November 26, 1795 and was described as the “longest on the river,” is said to have been nearly 1,000 feet long with six arched trusses. Palmer’s rebuilding, around 1812, only survived until 1818 when ice and high water destroyed part of it. The crossing then remained incomplete for ten years.

      Although Palmer’s early bridges all crossed the Merrimack River in Massachusetts, his fame spread, and in 1796 he was commissioned to build what was later known as the Chain Bridge over the Potomac River two miles above Georgetown at Little Falls. Chartered in 1794, the company hired Palmer and Jacob Spofford to build a multi-span bridge with a roadway that ascended and descended over each arched truss span. The longest was described as being 130 feet long with two additional spans that were shorter. Benjamin Henry Latrobe (1764–1820), a traveler from England, said it had been “framed in New England of white pine & brought hither by water,” suggesting that it was prefabricated, probably in Massachusetts, and shipped by water (1905). After its opening in 1797, it is said that George Washington routinely crossed it on the way to Mount Vernon. A critical French visitor wrote that it was “disgusting in its heaviness, having an immense quantity of timber and iron wasted on it” (La Rochefoucauld-Liancourt and Neuman, 1799). Not knowing that the bridge had already decayed and collapsed in 1804, Palmer wrote in 1806 that “the bridge I built over the Potomac at Georgetown in 1796 is not safe for heavy teams to pass over” (quoted in Peters, 1815). The Georgetown Bridge Company, owner of the crossing, duplicated the original, but only six months later a spring freshet destroyed the bridge. The third bridge, a chain suspension bridge, which gave the crossing its name, was built by James Finley (1756–1828) of Pennsylvania and John Templeman of Georgetown in 1807–8.

      In 1794, Palmer and Moody Spofford built this great bridge from Haverhill to Bradford, Massachusetts, over the Merrimack River. Each of its three spans was 182 feet long, over 30 feet wide, plus a short drawspan that allowed ships to pass. This photograph, taken during demolition in 1875, shows something of its structure. (NSPCB Archives, R. S. Allen Collection)

      Left uncovered until about 1825, the Haverhill Bridge received its open walkway on one side at a later date. (NSPCB Archives, R. S. Allen Collection)

      A view of Palmer and Spofford’s Haverhill Bridge in the winter when the bridge’s floor would have been paved with snow to allow sleighs to pass. (NSPCB Archives, R. S. Allen Collection)

      Originally built in 1795 by Palmer and Moody Spofford, the Rocks Village Bridge over the Merrimack, nearly 1,000 feet in length, lost two spans to a flood in 1818, these not being replaced until 1828. In this photo of the successor spans—none, apparently, the originals—an open turning bridge allows a sailing ship to pass. (NSPCB Archives, George B. Pease Collection)

      Although more and more bridges were being built by this time, two stand out. One was a two-span arched bridge built uncovered by Captain Boynton between May 5 and November 21, 1797 over the Kennebec River at Augusta, Maine, for $27,000. The eastern span collapsed on June 23, 1816, but a new bridge was not built until 1818 when the western span was also replaced. The second bridge, the Lansingburgh-Waterford Union Bridge, a 800-foot-long four-span bridge over the Hudson River in New York State, is the first known work of Theodore Burr (see further discussion below). If Palmer was bold, Burr was brazen, for each arched span was around 200 feet long, with 18-foot-high arches, and two roadways. Opened on December 3, 1804, this was the first bridge over the Hudson and remained uncovered until 1814. When it burned on July 10, 1909, it was then the oldest wooden trussed bridge in the country.

      By 1804, then, several builders had brought the science of wooden bridge construction to a surprisingly sophisticated level with many remarkable bridges and daringly long spans. None of them is known to have been covered with roof and siding, Peale’s assertion notwithstanding. Clearly, though, builders knew about covering bridges, but there was not yet general agreement on the benefits. None could deny, however, that in spite of tight joints, paint, or pitch, these glorious arches and trusses deteriorated if left open to the elements. The next step would lead to the creation of the first documented covered bridge in the United States.

      Bridge historian Francis E. Griggs Jr’s concluding remark on the significance of Timothy Palmer’s Permanent Bridge in Philadelphia, the country’s first known covered bridge, sounds a bit hyperbolic, but within the historical context up to that point, he is likely correct: “. . . there is no doubt that Palmer had designed and built one of the most significant bridges in the world and maybe the most advanced wooden bridge ever” (2009: 516). Additionally, thanks to its location and the attention it garnered both in the United States and Europe, there is voluminous documentation, including diagrams, paintings, letters, and contracts, but alas, no photographs. Palmer, however, who later partially rebuilt and covered his 1792 Salisbury span over the Merrimack in 1807, wrote in a letter: “Last summer, I rebuilt one of the Arches; the span of which is 113 ft and is on the same principle with your Bridge” (Griggs, 2009: 513). Since there are photos of this bridge, we can more easily picture the much longer but more artistically finished Permanent Bridge.

      Boston and Philadelphia were doubtless the two most important cities in the English Colonies at the time of the Revolution. During the revolutionary period, Philadelphia was the site for the signing of the Declaration of Independence, the writing of the Constitution, and the convening of the Continental Congresses. Following American independence,