Alonzo Johnson was born on 12 February 1828, in Bangor, Maine. He was the son of Lovisa (Underwood) Johnson (26 October 1805-20 April 1835) and Dolliver Johnson (1800-1884).
Alonzo Johnson obviously was an imaginative man and an excellent machinist. He had two patents for calculating machines, which he invented and kept improving their functionalities.
The first calculating device, patented by Johnson and Loomis, is used to add numbers up to 99. It was manufactured by James Loomis and Henry Conkey, another machinist from Springfield.
The second calculating device of Alonzo Johnson is an improved version of the first. It was a brass, wood, and steel device with overall measurements: 16.5 cm x 18.5 cm x 18.5 cm, used to add numbers up to 99.