A Theme and its Variations

Several years back I became highly familiar with The Bement Bridge in Bradford New Hampshire, this in a series of surveys while preparing a Structural Condition Assessment. That hard look was the genesis of a deep exploration of its named Truss Type, and a bit of a bio-exploration of its engineer patent holder, (and tangentially a running theme of an on-going wonder in how someone with no bridge building background might have come to design the complex joined timber truss that he did ) that exploration in large measure unfolded here on the pages of The Bridgewright Blog.

The Bement has recently recaptured my attention with my again working just a skip down the road from it, and with an area historical society recently making available several photographs which predate alterations made in recent decades. Changes structural and aesthetic.

The Bement with its original far more elegant Portal Trim - Image courtesy Hillsborough Historical Society - MPM Collection

The Bement with its original far more elegant Portal Trim – Image courtesy Hillsborough Historical Society – MPM Collection

In again skipping this stone of interest into the waters under this bridge, two ripples surface once more. Who was it who built it, and just what Truss Type is it? Individual Panel components typical to the named type are all there, and I am going to continue calling it a Long, while acknowledging it is a Variant. Many truss types are found in an array of variations, this perhaps driven by a desire to avoid the cost of patent royalties, or as explorations of capable minds guiding capable hands in looking for a better way.

The Bement while fitting the typ Panel component configuration of the type, varies markedly from Long’s patent, both in the number of these components – Single as opposed to double Posts, and not three, but four Chord Lams. Additionally the components vary completely in how they are joined to one another. The Braces and the Counters are reversed in their configuration and their number. And perhaps the most striking variation / departure from the patent are the absence of the pre-stressing wedges at the Counter Braces, a key feature of the type and the Colonel’s patent itself.

Double Daps and a reversal in number and purpose

Double Daps and a reversal in number and purpose

The Counters in the Bement fully join and pass through the Chord Lams in reciprocal double Daps, (simple notches) and do not simply abut the Chords & Posts with one wedged end as is typical to the typology – As if intended to act in tension as opposed to the norm of compression.

I point these features out for a number of reasons, foremost among these being that of a form of kudos for the bridge itself. There are other Long Truss bridges and Long variants still existing, and I have a deep appreciation for their detailing in how they are joined, yet find the simplicity of this little bridge intriguing, and worthy of admiration.

Secondly the historian in me thinks it just may be time to put to bed the oft repeated notion, that The Colonel himself built this bridge. The record does not seem to suggest where this bit of mis-information was first floated, but it is simply that. For Long’s whereabouts for the whole of the year, are well recorded in his work for and travels demanded by his position on the Board of Engineers for Lakes and Harbors and Western Rivers – He was nowhere nearby. And had he been in any way involved in its construction, I think it reasonable to suggest it would not have been a variant, but a textbook (Series of Directions to Bridge Builders) example.

So who did build the Bement? I think it safe to assume it was someone from the immediate area if not a local. There is not a ten mile distance from the Childs Brothers framing yard in Henniker to where the bridge stands, and there had by this time been a multitude of covered spans built all up and down the Warner River for both Railroad and highway use. There were those in numbers in the area with the necessary skills and knowledge to have designed and built it.

The Tie has been modified to carry a Flying Plate, the Rafter Seats now sits abandoned

The Tie has been modified to carry a Flying Plate and the altered Steplap Rafter Seats now sits abandoned

An interesting aside is the sometimes mention to the Bement’s Counter Braces and their joined relationship to the Chords as having similarities to Paddleford’s – The Bement shares (or did share) another even more uncommon feature, one found almost exclusivly in Paddleford’s, that of the Rafters joining the Ties in Steplapped Rafter Seats – Philip “Henry” bridged the Merrimack at Sewell’s Falls (but thirty miles to the east) in Concord just the year prior. (1853) Could our Bridgewright have maybe served on his crew and borrowed a detail worthy of repeating. I find it not improbable, and a smile rising with the realization and the on its head irony, that perhaps a Long variant was modified with influences driven by a Paddleford.

Here can be seen the Steplap Rafter Seats still serving their original purpose - Image courtesy Hillsborough Historical Society - MPM Collection

Here can be seen the Steplap Rafter Seats (Click to enlarge) still serving their original purpose – Image courtesy Hillsborough Historical Society – MPM Collection

Should you need a short span bridge, why should we not build a variation of The Bement, over another waterway, and set yet one more story in motion?

Commissions, consultancies and structural condition assessments always happily considered – Feel free to to reach out via the following “contact form”.

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Heritage Does Matter

Heritage Matters is a favored catch-phrase of mine, perhaps familiar to many of you as being the chosen name of newsletters and magazines published by those in the preservation / conservation community seemingly the whole world over.

I’m choosing to cite this phrase in this months entry in that I am penning it as a response to a number of recent news “stories” – stealth missions really, thinly veiled opinion pieces questioning the use of public monies to fund Covered Bridge preservation. The piece that touched a nerve, visited a single bypassed bridge, and suggests spending dime one to maintain such is wholly unreasonable, then goes on to intimate that funding maintenance on any example is money poorly spent.

I would ask those suggesting zero maintenance what alternative is it they see or might suggest. The funding of immediate demolition? The gating of Portals and simply letting time and neglect take the bridge to the river, someday accepting the inevitable expense of in stream cleanup and removal?

These are the only alternatives – Both are as silly as zero maintenance, and I would contend the cost of either would exceed the cost of decade upon decade of maintenance.

Postponing simple maintenance, is the unspoken of multiplier that drives up the cost of bridge rehabilitation’s. Timber does not simply go bad – Unchecked leaks in roofing or siding, and the buildup of dirt and leaf-litter, these all too easily preventable and correctable issues, are the causal factor in most all problems requiring any more than simple maintenance.

Putting aside that heritage tourism inarguably though indirectly offsets the cost of simple maintenance, (though perhaps not the costs of neglect) lets talk about heritage…

Unwittingly, even to those who care not one iota about history or historic preservation, Built Heritage still matters. In that this is where our sense of selves and place come from. The barns and historic homes we pass each day are our sense of place.

The Brownstones of Boston, Brooklyn and Harlem, the Victorian rowhouses of the Haight-Asbury, the Triple-Deckers of Mattapan, Manchester and Pawtucket, the Log Crib Barns of Appalachia, the Forebay Barns of Pennsylvania and beyond, all provide our sense of region and place.

This sense of place is also carried by the Howe Truss bridges of Oregon and the place-bound iconic Kennedy Portals of central Indiana – These things are all part of the landscapes which tell us who both we and our Grandparents are. These things are who we are.

Forsythe Covered Bridge, Orange Township Indiana - Photo credit  James W. Rosenthal - Use courtesy of The Library of Congress, Prints and Photograph Division HAER: IN-106-2.

Forsythe Covered Bridge, Orange Township Indiana, Built by Emmett L. Kennedy & Sons
Photo credit James W. Rosenthal – Use courtesy of The Library of Congress, Prints and Photograph Division HAER: IN-106-2.

Transportation Heritage like all Built Heritage is part of this little thought of, almost subconscious sense of who we are. With any and every example of our built heritage forever removed from our landscape, part of who we are is also lost. Place is now being endlessly eroded and homogenized as it is re-placed with strip-malls, chain restaurants and tract-mansions.

Heritage lost, is the loss of who and what we are, both as a culture and a people.

Why would we want to intentionally fail to maintain any of it?

Carpenters and their Marks

They’re everywhere and they are not, and perhaps that is part of the problem. With Carpenter’s Marks being somehow so ingrained in our collective subconscious, most everyone (even those without interest in historic carpentry and its methods) holds for them some blip of understanding, some seemingly just short of intuitive sense of their necessity and purpose. Perhaps this is why so much assumption is intertwined in much of the written description found on what and why they are.

Much of the supposition as to purpose is wound around how Timber Framed structures were often scribed, cut, and partially assembled in Carpenters’ Yards miles or more from where they were ultimately erected. While this is happenstantially true, it is only tangentially a driver in why the marks are necessary, and over-complicates the case. The real driving need for their use is far simpler than that.

Most Timberframe constructions have multiple copies of the same piece, arranged in assemblages of which there are also multiple copies, be they walls or bents or roof planes, or in the case of bridges, a pair of like trusses and the braced Tie and Floor Beam systems which connect them – Much to keep track of.

An atypical five at a Check Brace / Top Chord connection on Berk's County PA's Griesimer's Mill Covered Bridge - Roman numerals as used by carpenters vary from the norm to avoid confusion - Four is expressed as IIII instead of IV simply to make it impossible to confuse it with a VI - The same is true of Nine / VIIII - But Five is always V - This was in all probability mismarked as a Four and corrected with a fifth I

An atypical five at a Check Brace / Top Chord connection on Berk’s County PA’s Griesimer’s Mill Covered Bridge – Roman numerals as used by carpenters vary from the norm to avoid confusion – Four is always expressed as IIII instead of IV simply to make it impossible to confuse it with a VI – The same is true of Nine / VIIII – But Five is always V – This was in all probability mismarked as a Four and then mistake caught, corrected with a fifth I

Carpenters’ Marks are a simple system to identify place for each individual piece to properly maintain its relationship with adjacent pieces – In the most common form in which such marks are found, that means assigning the low number roman numeral to the reference end / reference corner of the frame, this most often chosen as the Southeast corner – The entirety of the first Bent is assigned Roman Numeral I – Differentiation as to East & West corners (and any pieces found between these) is achieved by incising that Roman Numeral with chisels graduating in size. To these numerals there are often slight variations added to delineate and describe placement as to such things as first & second floor…

Pieces can and do share the same Numeral like they share the same address

Pieces can and do share the same Numeral like they share the same address – These marks are found in The Sandown Meeting House ca. 1773 to be part of a Timber Framers Guild conference tour this coming week – See you in the attic – Though but 22 years of age at the time of its framing, Timothy Palmer of Schuylkill Permanent Bridge & Piscatiqua Great Arch fame is said to have been clerk of the works in the construction of this Meeting House

Scribe type layout is also a driver in the need for this system, with each individual piece, no matter how much it looks like a carbon copy of its opposite other, only fitting in the one place into which it was scribed.

Here a small Scribe Layup is in process, the three timbers above are being scribed into the same configuration as the co-planer set below them, a Rafter Pair with a Collar Tie - As this layup is completed individual pieces will receive their mark as they are taken to the horses to be cut

Here a small Scribe Layup is in process, the three timbers above are being scribed into the same configuration as the co-planer set below them, a Rafter Pair with a Collar Tie – As this layup is completed individual pieces will receive their mark as they are taken to the horses to be cut – Placement is assigned as the process begins

The system however survived the transition to Square rule layout, (See Dec ’12 archival entry – Overnight Turn on a Paradigm) simply as a proven aid in efficient assembly on raising day.

I still use traditional Carpenters’ Marks on both Scribed and Square Ruled frames. I find it both simpler and more interesting than a grid described with Sharpie markers & ABC / 123 – I’ve also found it holds appeal for clientele. This driven home some years ago in a newly raised house, with the owner beginning a friends introduction to the frame, not with a view of some interesting detail in the timber-work, but in pointing out the Carpenters’ Marks in the Great-Room. (These typ incised on reference faces in the area of the Brace joinery on both the Posts & Braces – ie: A standing height field of view) In watching his description of their purpose play out, his genuine enthusiasm for what he was working to describe suggested to me that he felt his choosing to build a Timberframed home was in some way including he and his family, through their home, in some nameless and timeless continuum – Something I feel part of each and every day.

Of Curves and Chords

In casting a wide net to both pull together a non-blog bio piece on Timothy Palmer, and in searching deeper for more information on the Trussed Arch Trusses a type commonly associated with him, (not to be confused with the Burr Arch images to be found below) I came across John Trautwine’s 1834 description of the construction of a ‘987 bridge (Then the longest Railroad Bridge in the world, built just one year prior) which came to be known as The Great American Viaduct – From The Journal of the Franklin Institute of the State of Pennsylvania Vol. XIV No.2 August 1834 – A piece titled – Description of the Viaduct near Peters’ Island – and thought excerpts worthy of a share here.

The whole of Trautwine’s description is ripe with seldom recorded details, from description of the coffer dams built to construct the piers, (and the steam engine used to pump them out) to the trestles emplaced to be used as falseworks on which to re/assemble the Trusses as they were erected over the Schuylkill. To how this Double Barrel was intended for one lane to serve rail traffic and one to serve foot and wagon traffic. (Several Philly area early Railroad bridges were two lane constructions for this purpose)

The following excerpt is intriguing in that it describes and pays homage to Palmer’s nearby Permanent Bridge which still stood at the time this Description was put to paper -

Always of interest to me is the period nomenclature (in this instance a wealth of it) found in this kind of first person source material – Here Joggle is again found to be the term of choice for the opposed swellings often milled into Posts in MKP variants to receive the Braces – It being to my mind logical to use common construction era terminology in our time also.

A rare treasure trove for wooden bridge geeks (this one in particular) are deep description of construction details little found elsewhere, detailing so descriptive the author begs pardon for the tedium borne by the reader…

I for one, am most thankful to John for these very details little shared, and this glimpse through time into his world, a world almost lost to us but for yet standing examples, and in words of description such as these, from the very minds of those who have left us our wooden transportation heritage.

We have yet to discover when this bridge was lost to time.

Phenominal Impact

Massive truck damage is again the subject of current news stories – In this most recent incident the level of damage is beyond any level of understandability, so far beyond, that it is without exaggeration almost impossible to understand how the truck and the fool piloting it, made it to the other side.

Impact damage has long been an issue with Covered & wooden spans, with but the 20th Century exceptions of Oregon and New Brunswick and British Columbia, most such bridges were built before heavy trucks existed and clearances were standardized.

We have spoken to truck impact damage here on The Bridgewright Blog in prior entries, and of how the frequency of these impacts and the level of damage both seem to be on the rise in recent years. GPS systems are often assigned blame by the offending drivers, this most recent case included. I can’t help but wonder however if some of this is not perhaps due to the continuing disappearance of through trusses of any kind from the National landscape. Modest span through trusses of any type are virtually no more. In their stead we are left with concrete deck bridges. None of the wonder of trusswork to perhaps spark the imagination of future builders and engineers. Just the continuation of an unending ribbon of pavement, unending road – Road seemingly levitated over water, supported by what, few who find themselves crossing even glimpse into the rear-view for a second glance at but a blip in passing to wonder…

Thought need not be spent, road is road.

Clearance and load limit signs are found less and less frequently on that road.

All that and I still can’t understand this level of unthinking – I drive a diesel fired behemoth, large enough that it is a pain to park in most parking lots, high enough that clearance signs in parking garages and drive thru’s need be heeded, heavy enough that I am pushing it with three ton load limit signs.

So somebody pointing a Semi through the Portal of something so atypical as a covered wooden bridge, passing load limit and clearance signs in the doing, is impossible for me to understand.

In helping the Graton Assoc's with the restoration of The Blair One of the tasks I was assigned was replication of the the many missing & impact damaged Wind Braces

In helping the Graton Assoc’s with the restoration of The Blair for these last many months – One of the tasks I was assigned was replication of the many all too common story, impact damaged & impact missing Wind Braces

I’m wondering with this entry, what needs be done to avoid more of this phenomenon of impact as the future unfolds?

Carpentry Made Easy

Long part of this rolling and ever ongoing obsession I hold in just what this is, this stuff of timber and bridge carpentry, has been an ongoing participation in the recovery of information almost lost.

These Trades nearly fell away as time morphed differing efforts, and materials towards those ends shifted away from what had been the norm for countless generations – Timber and its long evolving and practiced methods, would for a time be almost completely marginalized as dimension lumber and steel in their turn became the chosen norms.

Much in the everyday practice of these trades was no longer shared as the almost unspoken, was little conveyed in the fewer and fewer conversations of instruction were had over timbers on horses, as fewer practitioners found fewer up and comers interested in what was still there to be shared.

I spoke of how some of this, the spoken and shared side of this continuum was but barely saved, in Living Memory

Fortunately, though the everyday in a time when trades training was little written down, but shared one on one in literal Master to Apprentice relationships – Some in these transitional years of morph and change did take the time to put words to paper.

The collection of Treatises on Carpentry and method has also long been an ongoing obsession. This has in recent years become easier as the worlds libraries have become digitized, and the absolute need to find a rare copy of an often little printed work was now made everyday possible in public domain downloads.

I can’t deny I love my e-reader, and it is ripe with the works of among others, Sutcliffe and Dewell, Jacoby and of course Hodgson. And I do love being able to carry what amounts to a sizable electronic library with me anywhere circumstance demands I go.

I do however, still prefer the real thing, this the printed page. With everything this brings, the whole of it. Sounds and smells and a presence and physicality, the literal textural experience, the very textures of text, these often begging a reminder that I again flip open a neglected cover.

So when I became aware a specialty imprint had recently republished a particular favorite, a treatise that touches on the varied intricacies of Timber Carpentry, from the framing of mill buildings to that of spires & steeples, and because it touches on bridge building from a perspective little shared, that of a Bridgewrighting Carpenter…

I am now expecting a hardcopy to soon materialize shrouded in bubblewrap – For now an excerpt from a tome first printed in 1858

A Trust in the Truss

With last months entry we explored how a lack of any real framing configuration or behavioral similarities between Long and Paddleford trusses, made any real challenge to Peter from the Long camp, less than likely to succeed. ( The presumption that the choice not to patent was due to such pressure assumes Long’s agents somehow had inside information – Additionally, had they a case they still would’ve sued for royalties no matter what the truss was being called ) And while this does not mean there were no words exchanged, and that there was none of the bluff and bluster of empty threats. All the same, for me, none of this explains the choice which was made.

With why not explored, with this entry, I thought we would explore the potentials in why.

If I were to conjecturalize the whys as to Peter choosing not to patent his truss, this choice would not be for fear of a patent infringement challenge from Moses Long, sales agent to his patent holding brother – Though the Nineteenth Century was as or more litigious than our own period in time – Any such challenge would have been dismissed as groundless, as was the challenge to Howe. (which did and does share structural similarities) I think it more likely that the interest Paddleford had was in building bridges without paying patent royalties, not in any potential in collecting royalties from others – This wrapped around the failure of any realized return on an investment Peter made in patenting a spinning device decades earlier. The incentives to patent were perhaps, simply outweighed by the disincentives.

Long’s solid foothold in the area did lose much market share to the Paddleford, though I think that was maybe more about the typical norm that drove regional preference – Familiarity and area Bridgewright preference.

With some irony, the success the Truss Type enjoyed in the area is perhaps in part attributable to the type being patent and royalty free. The pattern of its area dominance suggests it also had to do with a willingness to work with others. A cooperative willingness, which created the very familiarity which drove acceptance and success. Both in towns willing to specify and purchase a trusted Truss, and an ability to assemble a trained and capable crew familiar with the complex joinery found in Paddlefords.

Many Intersections

From the beginning Peter partnered with Bridgewrights local to his contracts – Conway’s Jacob E. Berry, sometimes said to be participant in the first known Paddleford, would go onto specialize in the type, as would his namesake son. Both would help make Paddleford’s the dominant type in the Saco valley, and on over into Maine.

Peter’s own son, Philip “Henry” would go onto build his fathers truss with great regularity, in their home area on both sides of the river that forms the Vermont and New Hampshire border, and as far afield as the state Capitol. It is more than probable that he too collaborated with capable local framers.

The type continued to be built in numbers in its pockets of dominance, for decades after the two P. Paddleford’s time had passed, often with the use of even the unique detailing found only in Paddleford Bridges, unrelated to the trusswork.

At one time I wondered how the type had somehow not spread beyond a home range in which it enjoyed such huge success. Clearly it was none so much about a lack of patent royalties, as it was about trust and collaboration. Trust in a truss, both by the public, both in buying and and in choosing to trust their lives and livelihoods in daily crossing them, and also that of the carpenters who chose to frame them.

Even without the fine details, this is the stuff of fine story.

Long Puzzling over the Puzzlement over Paddleford

I have held a decades long interest in the Paddleford Truss, this first brought on by visits to standing examples, these found only here in Northern New England. And then out of a professional interest, first in a bridgewrighting timber frame carpenter’s appreciation for the way the Truss Type is joined, and in how loads are conveyed and resolved. In time my appreciation came from eyes and hands on experience with the typology, this now dating back a full decade to a restoration project I was involved in back in ‘ 04

With the initial and recurring subject of this weblog being Truss Types with roots here In New Hampshire, and my complete favor for this type I have long wanted to pen an entry based on this Truss and its developer Peter Paddleford. Work to find information for a bio-sketch of the man, even with his many successes, and hints of a long running set of shops and mills in his adopted home town of Littleton New Hampshire, any real sense of his life information is sadly proving to be lightly recorded, and a bit of a challenge to churn up.

Attempt to find information on his namesake truss, likewise reveals little but how the type was limited to a smallish home range, and the fact that Peter never patented his truss unlike so many of his fellow truss type developers.

This seems to have puzzled many and has spurred an odd and oft repeated conclusion that has long puzzled me. This being that this failure to patent is directly tied to some similarity shared, and a challenge from agents of Col. Long and his Patent Truss.

To my mind no such similarity exists, nor have I been able to find record of any such challenge, only allusion to said challenge repeated time and again. So I’ve decided this entry will examine this notion, by looking at the dissimilarities between the Truss Types.

With Long and his Trusses also having deep roots in New Hampshire, we have delved into his story time and again here on the Bridgewright Weblog. (click in the search box for a list of entries) His Patent Trusses feature double Posts at each panel point to which are joined double Braces which sandwich a Counter Brace, these wedged to create the Colonel’s groundbreaking pre-stressing of his Truss, (he was first in conceptualizing pre-stressing – One reason some name him as the worlds first “true” engineer) and allowed control of the geometry of each individual Panel.

The arrangement of framing in a Paddleford bears no resemblance to a Long whatever – They are simple single Post / single Brace panel arrangements which feature an ingenious tensile Counterbrace which is joined to not a single panel, but parts of three – It does not form the sandwiched X common to Long’s and Howe’s, (which did spark a challenge) and quite counter to the centered and sandwiched example in Long Trusses, the Counter Brace is not centered and is not a compression member. Paddlefords unlike Long’s are a Multiple King variant, simple MKP Trusses with an added tensile Counterbrace.

This notion that a Paddleford is a modified Long holds no water, and has long done disservice to the man and his Truss, and has caused many to somehow overlook the greatest aspects and the simple genius of his Truss.

The Counter Brace is double dap joined to two Posts and in a symmetrical mirror image arrangemet, to both the Top & Bottom Chords - Buttressing the Posts and countering the moment in the doing

The Counter double daps two Posts and both the Top & Bottom Chords- Buttressing the Posts and countering the moment in the doing

This genius lies in the placement of his Counter and how it both conveys and imparts load along the Truss and in the doing both captures the Brace and locks it in place on its Post abutments and buttresses the moments imparted by the Braces to the Posts which receive them – These bending moments are the Achilles heel of Multiple King variants, and Peter’s carpenterly solution, was and is to this simple bridge carpenter, (like the loads through his tensile Counters) a great leap forward.

The Last Master Builder

In our delayed return to things Trussed Arch, we must first acknowledge two Bridgewrights we have already touched on here on the weblog. Both built in this form and tradition, both were contemporaries of the subject of this entry – Timothy Palmer of Great Arch & Permanant Bridge fame, and Theodore Burr, his name forever appended to Arch type bridges, though paradoxically not for his ahead of its time Delaware River masterwork.

Both were Master Builders, an archetype then long recognized – Those not just who had reached the complete command in a “physical” ability in their chosen craft at a skill level beyond their brethren, and also that uncommon ability, to see every layer of intricacy necessary to the planning and management of any project – And somehow also, an innate ability to visualize, design, and then draw, anything, (no matter how complicated) they were planning to build.

We cannot fully explore this Truss Type without discussing Lewis Wernwag, the Bridgewright whose works suggest he was the master of this typology. His prolific life’s work is most often exemplified in descriptions of his 340′ clearspan Schuylkill River masterwork known to history as The Colossus. This best illustrated in Lee H. Nelson’s highly recommendable book devoted to this single bridge – The Colossus of 1812: An American Engineering Superlative.

So much in fact has been written about the man and his works that we’ll not directly discuss his life in any bio type format, nor will we have a full hard look at The Colossus.

"A View of Fairmount and the Waterworks" by John Rubens Smith painted just three years prior to its loss to fire

“A View of Fairmount and the Waterworks” by John Rubens Smith painted just three years prior to its loss to fire – Image courtesy of The Library of Congress

Our exploration will center around aspects of his design that suggest his understanding of his use of materials, choices which exemplify his complete understanding of his primary chosen material. And then discuss how his work moved beyond the Arch type bridges so common to this early period of bridge innovation

My intrigue with his chosen detailing goes to two things which deeply illustrate his understanding of wood as a building material, details that are today too often overlooked. These being that unwritten bridgewrighting rule of all timber needing be with every opportunity, spaced apart. In the case of The Colossus, in part by wrought iron “Links” These links, a clamp of sorts to serve as part of the Chord assembly, they also secondarily, though no less importantly served as spacers to provide airflow, and prevent large areas of wood to wood contact. ( The Colossus made great use of Iron – 40 Tons – Wernwag purchased an area nailworks & foundry in anticipation of the project ) And though it went unsaid this was obviously also to provide and maximize the ever- important airflow that affects the quick drying of any unintended wetting. The other detail I find interesting is one often cited in descriptions of this bridge, this of all its timber being “Slit through the heart” Always with this citation too much is seemingly made of his reference that this was done to “Show any defect” – Yes this was a secondary benefit of milling smaller baulks from large diameter sawlogs, (as was the norm to the period) this was without doubt also about other benefits wrought from such milling. His chosen six inch breadth is not just about staggering splices, it is also about rapid seasoning and thereby reducing the dead load of the bridge superstructure as quickly as was possible. It was also probable that in the doing at least twice the amount of curved Chord leaves were realized in the milling of his candidate sawlogs. (in all probability naturally curved – We know Palmer chose such for his Chord Lams) And the benefits of such milling do not end there. I would contend “Slit through the heart” is period jargon for what has come to be known as “Free of heart center” One of the betterment’s gained in FOHC milling is a reduced tendency in season checking, greatly reduced both in size and number. Lewis’ long experience in millwrighting would have him understanding what encouraged rot in wet environment constructions. Large leak catching open checks caked full of moisture holding dirt are one of those avoidable encouragements. And the aspect of FOHC that most overlook is the term Center, meaning heartwood, and the complete absence of sapwood. Sapwood is highly susceptible to the fungi that cause Brown Rot, and in my opinion its use should be avoided in the framing of bridges. With longevity and rot susceptibility clearly being high in his mind as he designed The Fairmount, I think it not a stretch to suggest this is an opinion he and I share. We are also of the same mind that Eastern White Pine for reasons which still hold true, is the go to choice in species for bridge framing.

Somehow today those who specify material for wooden bridges and the rehabilitation of historic spans, rarely spec dense ring count or FOHC even though both are readily available in their go to species of Douglas Fir. A species I do not see as across the board appropriate for all truss types, or to certain timber joints. This though is perhaps a discussion for another time.

Some might see some of what I suggest as just so much supposition. (and I am among those who revile revisionism based on groundless conjecture ) However I am in part reacting to such seen in earlier descriptions of Wernwag’s Collossus, and my conjecture is grounded in an intimate knowledge of these constructions, their methods, and their materials.

It is interesting that unlike his early Arch Bridge contemporaries, Wernwag transcended the Arch and also built in what some call true trusses. This was perhaps driven by an interest in keeping costs down by eliminating the needed mass and added complexities in abutments designed to carry Arches. This interest was perhaps driven by movement requiring repair, which developed in his abutment there on the western bank of the Schuylkill.

A detail from Lewis’ Neshinemy Bridge included because it is an example from one of his “Truss” bridges. That, and I simply love Strong-Arcs, and I see them as under appreciated. This, and with that the source material seen here, dates from the mans very lifetime.

As dusk descended on Wernwag’s life and time, a new age was slowly dawning. The role then long existing in mankind (from the dawning of man’s great works, from standing stones to our ancient temples and pyramids, to builders of tunnels & aqueducts to those who designed and oversaw the building of the great Cathedrals) which he had filled so well, that of a highly technical designer who was also a highly skilled rigger and builder, was then stratifying into specialties seen to no longer overlap, and to be seen by some to have very different places on the societal and hierarchical ladder. In truth, we are perhaps little the better for it. It is only with the possession of both skill sets, and both sets of understanding, each equally and finely honed, that anyone can truly be, a Master Builder.

It’s All in a Name

Things Trussed Arch are still building and burgeoning on the coming horizon, though this entry holds a brief diversion…

A recent comment on an earlier bio-piece entry I had put up on a New Hampshire born Truss patent holder, ( See New Beginnings ) from a friend and fellow bridge historian, pointed to an error made in spelling of the surname of an associate of the subject of the bio-piece. In my reply I defended with reason my decision to use the variation I did.

Being that I pride myself with accuracy relayed in the histories found here on the weblog, and not just the simple rehashing of the work of others. And being that there is also an undercurrent here of working to solve the occasional mysteries sometimes found to be lost or mixed up in the details of history. Particularly when those details twisted or lost have to do with someones name, (as in the needless confusion surrounding Nichols Powers) a deeper look demanded attention and as always, more was there for the finding.

The subject of this ramble was a partner in a Cleveland Ohio bridge building firm and agent of the subject Patent Trusses described in New Beginnings, and himself a patent holder of a a variation of a deep area of interest for me. He holds No. 47,395 a “Splice for Timbers” And though his name appears in ample written records spelled two ways, in almost equal numbers, it was the seeming spelling found in his own signature in his letters patent which drove my earlier decision. A deeper look said more about him, his partner and their bridge building concern. Also revealed was the proper spelling of the mans name.

Both partners served the Union in the war of their time in bridge building units that like others described here in these pages seemed to have been the basis of lifelong relationships. and like others they served under the command of fellow patent holder, Daniel Craig McCallum Military Director and Superintendent of the Union railroads.

In the the years immediately following the war Henry assumed an owners share of Albert McNairy and partners bridge building firm of Thatcher, Burt & Co which then assumed the mantle of McNairy Claflen & Co. Within the decade the company was said to have three hundred and fifty men in their employ and reaching two millions of dollars of business annually. In Cleveland Past & Present published in 1869, NcNairy Clafen is described as “From 1851 to a recent date, the Howe Truss Bridge was nearly the only bridge made by the concern. They now are largely engaged in the construction of iron and combination bridges. The concern has built three thousand two hundred and eighty-one bridges–about sixty miles in the aggregate. The streams of nearly every State east of the Rocky Mountains are spanned by their bridges, and it is a historical fact that not one bridge of their construction has fallen.”

This fits all that was found in the dismantling of the Bell Ford, an amazingly sophisticated construction for 1875. Both the foundry work found in the iron, the castings, and the wrought eyebars, but also in the woodwork. Thatcher & Co’s decade of Howe Truss construction showed itself both in the Shear Block joined Top Chords with their patent Claflen Splices, and also in the compression diagonals (Braces) which swell to a greater dimension at mid-length, something I contend because of amazingly uniform mill & tool marks, are a product almost out of time, and were completely produced by some sort of duplicating machine.

In the Bell Ford even the simple joints joining the Braces to the Cast Sockets which received them were remarkably consistent and lacked any appearance of having been worked by hand - Suggesting a wholly mechanized approach to production

In the Bell Ford even the simple joints joining the Braces to the Cast Sockets which received them were remarkably consistent and lacked any appearance of having been worked by hand – Suggesting a wholly mechanized approach to production

From his time, both a description of the the mans life’s work, his likeness, and his signature.


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