Thoreau is sometimes mistakenly thought of as a sort of hermit or vagabond, but in fact he was completely serious about carrying on the family business, a factory producing pencils. He made significant improvements in their manufacture and engineered a machine for grinding "plumbago" ([[graphite]]) more finely to produce a higher-quality "lead". Thoreau pencils were regarded as being among the best-manufactured in the U.S.<ref>Petroski, Henry (1989), "H. D. Thoreau, Engineer." ''American Heritage of Invention and Technology,'' volume 5, issue 2 [http://www.americanheritage.com/articles/magazine/it/1989/2]</ref><!--Also in Petroski's 1992 book, "The Pencil: A History of Design and Circumstance"---> | Thoreau is sometimes mistakenly thought of as a sort of hermit or vagabond, but in fact he was completely serious about carrying on the family business, a factory producing pencils. He made significant improvements in their manufacture and engineered a machine for grinding "plumbago" ([[graphite]]) more finely to produce a higher-quality "lead". Thoreau pencils were regarded as being among the best-manufactured in the U.S.<ref>Petroski, Henry (1989), "H. D. Thoreau, Engineer." ''American Heritage of Invention and Technology,'' volume 5, issue 2 [http://www.americanheritage.com/articles/magazine/it/1989/2]</ref><!--Also in Petroski's 1992 book, "The Pencil: A History of Design and Circumstance"---> |