Thomas W. Stewart was an American inventor who made improvements to the mop and invented the railroad indicator and a metal bending machine, according to About.com. Stewart was born in Kalamazoo, Michigan in 1823. Stewart was one of the first African-Americans to be awarded a patent.
Thomas Stewart's first invention was a station and street indicator patented in 1883. Before this invention, there were only street signs warning of crossing trains and street cars. The indicator could be activated by a lever built into the tracks that indicated a train or street car was approaching.
Stewart's next invention was an improved mop design that is still in use. In 1893, the year Stewart invented the new mop, the only available mops had to be wrung out by hand. Stewart improved upon this design by adding a clamp and springs that allowed the user to push a lever that wrung out excess water. Stewart also made the mop head detachable so users could replace or clean mop heads as needed.
Stewart's last invention was created in 1887 and was a metal bending machine that had the capability of oscillating. This invention made the process of bending steel safer and more efficient.