AUBURN — Sitting behind the Foss Mansion on Elm Street earlier this summer watching bats, Bill Hamilton heard some creaking and watched in horror as a piece of history came tumbling down.

A section of the back wall on the 100-year-old mansion, now headquarters of the nonprofit Woman’s Literary Union of Androscoggin County, had been rotting and finally broke off.

The entire structure, except for that back portion, is made of concrete, he said.

“That’s why the rest of the mansion is in pretty good shape. But you see, it’s really confined in there and not much sun gets to it, so it has been rotting away. It was time to fix it up,” Hamilton, the local architect overseeing the project, said.

While watching a crew from Bragg Masonry of Sumner strip off the rotted facade, marveling at the unique construction and attention to detail, something nearby caught Hamilton’s eye. A piece of the old, decorative railing around the top of the portico was coming loose. When he got a look at a cross section of the top railing, he was floored.

“I’m guessing this came from a Douglas fir tree from northern Maine, and wouldn’t be surprised if it was 700 years old. The timing certainly fits,” he said.  

Looking at a cross section cut from the railing, the rings are not circular, indicating it was cut from a section near the outer edge, not the center. The rings, tightly packed together, suggest old-growth forest, like what Henry David Thoreau wrote about in his book, “The Northern Woods,” Hamilton said.

“It would make sense and the time frame certainly fits,” he said. “Of course, those trees are all gone now and the only place you can get something like that would be from Oregon. But back then, they would have been used in local construction.”

With the aid of digital photography and computer programs, Hamilton plans to take measurements on the slight curve of the rings and extrapolate it until he gets a full circle.

“What you see here is about 200 years of rings, and there is hardly any curve to the pattern,” he said. “I am pretty certain after we do the calculations, it will tell us that the tree is about 700 years old. Isn’t that amazing?” he said.

Hamilton plans to cut thin cross sections from the railing to mount and sell as a fundraiser.