Benjamin Bradley -- USA

Benjamin Bradley was born a slave in Maryland around 1830, at that time, it was unlawful to teach a slave how to read or write.  Through the contact with his master's children Bradley was able to learn anyway.  He was good at mathematics and showed a natural talent for making things.

When Bradley became a teenager, he was put to work at an office in a printing company, during his spare time he built a working steam engine from pieces of scrap metal. Impressed by this feat, his master arranged for Bradley to work at the Department of Natural and Experimental Philosophy at the Naval Academy in Annapolis, Maryland. There Bradley set up and helped conduct experiments, Professors at the Naval Academy were impressed, as he was smart and quick to learn, and didn't make mistakes when he prepared experiments in the laboratory.

Bradley was paid in full for his work, but as a slave the money had to go to his master.  The master allowed Bradley to keep five dollars a month, he saved the money he earned, and sold his original model engine to a student at the Academy.

Bradley then used his savings to develop and build an engine that was capable of propelling the first sloop-of-war (a small warship carrying guns on one deck) at the rate of 16 knots an hour. His engine was the first ever created that was powerful enough to run a war ship.

As a slave, Bradley could not get a patent for the engine he developed, he was however, able to sell the engine and keep the money.  He used that money to buy his freedom, and lived the rest of his life as a free man.