I went off on a tangent recently, of sorts anyhow, more of a refocus.
One of my areas of interest is New Hampshire’s connection to the history of wooden bridge building, a history which is rich and long, yet still continues. This beginning with what was the longest of Timothy Palmer’s Trussed Arches, known to history as the “Great Arch” , a 244′ span over the Piscataqua, part of a 2,362 feet long and 38 feet wide bridge which allowed locals to navigate the Great Bay, an amazing first, dating to 1794.
A decade later, and in the century that followed, New Hampshire was particularly well represented in bridge building in a century of massive change . This change driven, by a rapidly expanding country, and the spirit of innovation found in new ideas and new beginnings.
New Hampshire was the birthplace of a number of Truss patent holders and bridge building innovators, some whose life’s work was done here, some who traveled far on that new spirit of American innovation.
This tangential trip, was into the life and work of New Hampshire native son Col. Stephen Harriman Long and his patent trusses.
I recently did a structural condition assessment on a Long Truss Bridge which took on a modest lean this past winter. As such hard looks often do, this prompted a little burst of renewed research on not just this bridge in particular, but on the truss type as a whole. Always a favorite of mine not just for the local connection, but as a bridgewrighting carpenter. A Long is a framers bridge, something of a timber frame carpenters dream.
Though I’ve long had a photocopy of an original from the collection at the Thayer School at Dartmouth, (Long’s Alma mater, the college, the engineering school did not yet exist – He left Dartmouth in 1809 having spent $94.56 on his education, and still $15.33 in debt upon graduation ) this research led me to discover that Long’s book on bridge building has both been recently digitized and is also unexpectedly back in print.
Stephen’s college debt was about what I paid for my new hardcopy of his long out of print thesis. In reading yesterday, the chapters titled “A Series of Directions to Bridge Builders” in section XVII – OF THE BRIDGE FLOORING – I was happy to find another contemporaneous description of the system we replicated at The Gilpin’s, which I described in my last entry.
Sometimes hard to read, all the same, I like contemporary descriptions as source material and try to defer to them in assigning names to parts and pieces, and use the terminology chosen by the builders and patent holders unless some other term had since become the term of choice amongst bridgewrights in the years which have followed.
A snippet, in the mans words –
“The floor guards consist of timbers about 3 by 12 inches, placed edgewise in contact with the posts and main braces, and on both sides of the road-way, the lower edge being coincident with the lower sides of the flooring plank, which last are prevented from slipping endwise by reason of their confinement between the guards.
The floor binders are ribands of any convenient dimensions, attached to the guards in a manner to confine the ends of the flooring plank, and keep them in their proper places.
In cases where all the parts of the flooring here considered, are applied, no nails spikes or treenails, will be required as fastenings for the floor.”
From – Description of Colonel S.H. Long’s Bridges: Together With A Series Of Directions To Bridge Builders – This was originally released in 1836 by the publishing house of J.F. Brown in Concord NH, during a brief period while the Colonel returned to and resided in his hometown of Hopkington – This revision and re-release reflects changes and addendum’s born of the 1839 patent
A link to the digital copy – http://tiny.cc/yz30s
Yes, I guess that puts me squarely in the Bridge Geek camp.