Washington, D.C. 1865. unbound. 4 pages on vellum, 20 x 15 inches, Washington, D.C., December 5, 1865. Very scarce patent issued to William M. Henderson, a resident of Baltimore, Maryland, with an original highly-detailed drawing of an independent steam engine, colorized on heavy waxed paper identified as "IMPROVEMENTS IN DIRECT ACTION INDEPENDENT STEAM ENGINES," with a technological page devoted to the explanation of how Henderson's invention would function. Fine signature by the Secretary of the Interior, W.I. Otto. All seals and ribbons still attached. Heavy natural folds, but still in very good condition.
Mechanical engineer and inventor credited with designing and improving a slide valve engine, a force pump, hydraulic brakes, and components associated with the steam engine.