John Thoreau Pencils Set of 4
 
John Thoreau entered the pencil business in 1823, after his brother-in-law discovered a vein of plumbago, or graphite, in New Hampshire. Thoreau & Co. quickly gained recognition for their high-quality pencils.
 
By 1829, their pencil manufacturing moved to Concord, MA John’s son, Henry David Thoreau, became involved in the business and started to dig into the manufacturing problems that had made American pencils notoriously inferior to European imports. After researching it at the Harvard Library in 1840, he hit upon the idea of using clay—rediscovering what the French had figured out 45 years earlier—to make the perfect graphite mix. Henry’s formula for kiln-fired pencil leads—a mix of finely ground graphite and clay—could be reliably graded from hard to soft.
 
John Thoreau & Co. was the first American pencil manufacturer to market pencils using a standard of hardness, graded 1-4.