history-computer.com
The 1850 US Census details him as a watchmaker, though he added a few skills over the years. In the 1860 US Census, Hatfield moved to Sandusky, Ohio, and worked as a photographer (ambrotypist).
Hatfield is known for three patents, but the adding machine is the most popular. It had a number of metallic disks with numbers stamped and set with springs.