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VOL. 42 | NO. 16 | Friday, April 20, 2018

Honest, Abe, it isn’t your cabin

UT team proves, disproves authenticity of historic wooden artifacts

By Joe Morris

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A good story dies hard, especially if it’s at the center of a tourism attraction. That’s why the park rangers and officials at Abraham Lincoln Birthplace National Historical Park in Hodgenville, Kentucky, are to be commended – they wanted to know if the cabin that had long been touted as Lincoln’s birthplace actually was and were willing to take their lumps if not.

But how to find out? Enter Dr. Henri Grissino-Mayer, associate department head and the James R. Cox Professor of Geography in the University of Tennessee-Knoxville’s Department of Geography.

Armed with a group of eager students, advanced software capable of identifying historical tree-growth patterns and a drill, Grissino-Mayer is the guy you call to see if your wooden antique is really … well, antique.

Dr. Henri Grissino-Mayer, director of The University of Tennessee’s Geography department’s Laboratory of Tree-ring Science, is one of the world’s foremost experts in the field of dendrochronology: the science or technique of dating events, environmental change, and archaeological artifacts by using the characteristic patterns of annual growth rings in timber and tree trunks. He inspects wood samples with graduate student Savannah Collins.

-- Adam Taylor Gash | The Ledger

First, a primer. What Grissino-Mayer does is called dendrochronology, or the use of tree rings to date events, environmental change and artifacts. He’s been doing it for more than 30 years, including a stint at the University of Arizona Laboratory of Tree-Ring Research in Tucson, established in 1937, and one of the world’s leading facilities.

So, if you’ve got an object – log cabin, violin, dugout canoe – he’s the guy who can assess the tree rings, use some comparative data to look at the type of wood, where it was grown, the weather patterns that affected growth and several other variables – and presto! Beginning and end points for the tree’s life, allowing for dating of anything made from it.

See the University of Tennessee team at work on the Lincoln cabin.
https://www.cbsnews.com/news/did-abraham-lincoln-sleep-here/

“Ever since I got here in 2000 my students and I have been taking off to date log cabins,” Grissino-Mayer says. “We have done several in Tennessee and other states, and most recently did the work in Kentucky on the Lincoln cabin. The university is letting us provide a very valuable service to the state, to the National Park Service and even to homeowners, landowners, historical societies and agencies.

“A lot of people want their artifacts, big and small, evaluated and dated, and we really enjoy getting out into the field as well as doing the work in our lab.”

Not everything made out of wood can be dated, and some trees are easier to pin down than others. Log cabins are a fairly easy chore because the most common wood used in their construction is oak, which Grissino-Mayer approvingly explains forms “very nice” tree rings.

“Luckily for us, the early settlers in the Southeast were using oaks for logs, and we also see pine and tulip poplar, all of which give us nice rings because they are big trees,” he adds.

Dr. Henri Grissino-Mayer recently traveled to Kentucky to take core samples of logs used in the construction of two log cabins that claim to be the birthplace of Abraham Lincoln. Grissino-Mayer was able to disprove the validity of the claims; the trees actually dated to the 1860s and 70s after Lincoln had already been president.

-- Adam Taylor Gash | The Ledger

Once a dating project is agreed to, the team evaluates the item to see if it’s made of a species that can be dated by rings. Then they look at how many rings are in the logs – they prefer at least 60, preferably 80 or more, because the older a tree is, the more accurately the statistics for dating can be applied.

Then they look at the preservation quality – if there’s hollowing or decay, for instance, then there’s not enough inner material to work with. If the structure passes muster, then the team piles into a van and heads out for a field visit.

Dr. Henri Grissino-Mayer, director of The University of Tennessee’s Laboratory of Tree-Ring Science, is one of the world’s foremost experts in the field of dendrochronology.

-- Adam Taylor Gash | The Ledger

That was the case in Kentucky, where CBS Sunday Morning and other journalists caught up with Grissino-Mayer and his students as they worked (see box for link).

They don’t take every cabin that comes their way – inquiries average about one per week – or there’d be no time for teaching and studying, but this one’s alleged lineage was too rich to pass up. Plus Grissino-Mayer had already dated another cabin in the park, so his work was familiar to the team there.

“I do have to be very selective, but we do a lot of field work as well as lab work because there’s not enough people with tree-ring dating skills in the Southeast; I wish there were more,” Grissino-Mayer says. “We only do three or four trips a year, and those are the ones I feel we will have success in for dating. We spend a few days doing taking samples and then head back to the lab and begin our process.”

More on that process later. For now, back to the Lincoln question: Was he born in that cabin? Nope.

Turns out the logs dated from 1861, when he was already president. The results weren’t a huge surprise to park operators, who figured that the cabin’s origin story was more handed-down legend than fact.

Still, they say, the fact that Lincoln was born in the area is more than enough to lend the park historical significance, and visitors can learn much during their visit by viewing the cabin as representative of its time and as a showcase of the 16th president’s humble roots.

“As we explain to visitors, it’s immaterial to us if Lincoln lived in this cabin or not; it’s a symbol of how he lived, and where he came from,” explains Stacy Humphreys, chief of interpretation and resource management at the park. “Now we have great information about the cabin that’s not based in legends and stories, and so we can tell its real history alongside the president’s story. He was born here, he moved to other places, but he often talked about this area.

“We still have a lot of history here, including these cabins, even if they’re not ones the Lincolns lived in.”

Proving cabins to be historical or just old is but one task to which the UT tree-ring corps devote itself.

Next up for Grissino-Mayer and his students is a canoe. A museum in North Carolina recently had them date two Indian dugouts, and word of that success has led to work for the state of Florida on a canoe that emerged from a riverbed thanks to the churning caused by Hurricane Irma.

In between their road junkets, there are violins, banjoes, totem poles, even an heirloom cribbage board under the microscope. At stake are historical reputations and money.

Is that violin a Stradivarius, like dear old grandpa always said? If yes, possibly worth millions; if not – not so much. Tree-ring dating can lead to hurt feelings, Grissino-Mayer says, but the wood doesn’t lie.

“We get a lot of requests to date musical instruments because we are one of only a few labs in the world that can do so,” he adds. “We began doing that in 2001. It’s mostly violins, but we also do guitars. These instruments are nicely varnished, and we can look at them from the side and see those tree rings. We put them under the microscope and there are the wood grains for us to study.”

And when the results are less than stellar? He recalls an outcome in which the violin was alleged to date to the 1700s and in fact was made in 1890. The results didn’t go down well.

“People can be very unhappy,” Grissino-Mayer acknowledges. “People will disagree with our assessment and stick with their oral tradition. This gentleman was really mad.

“This happens to me, and to my colleagues, which is why we are very selective. We also prepare people for what they may hear. We let the trees speak for themselves. They don’t stretch the truth, they don’t fudge the data.”

It’s not all tears and shattered dreams of a plum appearance on “Antiques Roadshow,’’ however. Sometimes the history aligns with the facts.

When Belle Meade Plantation in Nashville wanted two cabins on the antebellum mansion’s property dated to see if they matched up with a plaque declaring they were built in 1807, the process provided authenticity to the claim.

“They were exactly that age. It’s always great when we get a winner,” Grissino-Mayer says.