Benjamin Banneker was a remarkable man in an age of remarkable men. With interests in astronomy, scientific agriculture and engineering, he helped pioneer crop rotation, wrote a farmer's almanac and tracked the 17-year locust cycle. He helped locate sites in the planning of Washington, D.C., and he theorized that Sirius was actually a binary star more than 200 years before modern telescopes could substantiate this observation. His 1791 letter to then-Secretary of State Thomas Jefferson is among the earliest civil rights protest writings. Despite all his innovations and accomplishments, however, Banneker developed only two inventions: An all-wooden striking clock and the reverse mortgage.

A Striking Clock

Josef Levi gave Banneker a pocket watch after the young man showed interest in it. Banneker then examined its components. Biographer Louis Haber recounts that Banneker received from his former teacher Sir Isaac’s Newton’s “Prinicipia” and a geometry book, as well as a picture of a clock. From these materials and his work with the watch, Banneker invented his own version of a clock that could strike on the hour. He hand-crafted all the parts of wood, and it worked for 40 years.

A Reverse Mortgage

At age 60, Banneker wanted to have more time for intellectual pursuits and spend less on farm work. He sold his farm to his neighbors, the Ellicotts, for £180, but he continued to live in the farmhouse. They "paid" him in credit at their store, then reimbursed him a cash balance at the end of each year. They received the farm and house upon his death. In setting up the deal, Banneker devised a sophisticated mortuary table and estimated the property’s value; this arrangement became the basis for today’s reverse mortgages.