Baxter, William
The Baxter engine, also currently called the Colt-Baxter steam engine, was patented in 1868 by William Baxter. Colt's Fire Arms Manufacturing Co. began producing it in 1871.
Multimedia:
Video of steam engine: Baxter Steam Engine and Boiler, c. 1868 – New England Wireless & Steam Museum
Images: The Colt-Baxter Steam Engine