Jayharley:
Your tip on the Concord Museum proved very fruitfull. I called them and talked to David Wood, curator. He was very knowledgable and accomodating. He stated that Henry David Thoreau's pen knife was not in any collections that he knew of, it is felt that Frank Sandborne or Nathanial Hawthore may have had posesion of his last knife. He stated that Thoreau was an excellnt craftsman, loved good tools and knew how to use them. The mortices he cut in constucting his home were perfection.
He also commented that as a surveyer and writer Thoreau's knives probably included a true Pen Knife and he used it for sharpening his pencils and qull pens. The model called a "Pen Knife" is well established. I saw a photo of several in Northwest Knives and Collectibles recent catalog and ordered one dating from the 1850's made in Sheffield. They did not have a Rogers Pen Knife, but this is close. Elephant Ivory scales, nickel silver bolsters.
Can't wait and thanks to all for sharing thoughts with me.
Take Care