On 26 September 1854, a certain Aaron L. Hatfield of Lewisburg, Pennsylvania, took out a US patent №11726 (see the patent of Hatfield) for a machine for adding numbers. The adding machine of Hatfield, the inventor and manufacturer of adding machines who flourished in the middle of the nineteenth century, was in production for some years by the inventor himself (see the lower photo), and several devices survived to the present time.
The calculator of Hatfield (see the lower drawing from the US patent №11726) was made of wood (mahogany), iron, and brass, with dimensions 2.5 cm x 24.5 cm x 14.5 cm. It was an adder with carry and consisted of a series of circular metallic disks having numbers stamped thereon, so arranged, in connection with springs, that by the alternative movement of a lever, any number of figures, from 1 to 10000 or more, maybe correctly and easily added together before the eye.
The adding device is mounted on a mahogany base plate in the shape of a handheld mirror. There is a hole at the end of the handle for hanging the machine.
The calculating mechanism consists of three, concentric brass discs of different diameters, that are mounted on top of each other and to the mirror portion of the mahogany base.
The largest disc is fixed (glued) to the mahogany base, and it has the numbers from 1 to 99 indicated around the edge (there also is a blank space for zero). The middle and upper discs rotate about a central pivot, which has a smaller pin attached to it that holds the discs together. The middle disc is divided into 100 parts around the edge, with the parts numbered from 100 to 9900 (again there is a blank division). The top disc has the numbers from 1 to 99 around the edge, as well as a blank. Next to each digit of the disc, there is a small sunken tooth in the disc. A hole in the arm allows one to see numbers on the discs.
To use the instrument, the operator sets up thousands by rotating the middle disc. There is an iron handle at the very end of a crossbar (attached to the common center of the discs), with which the operator rotates the bar. To add one or two-digit numbers, the operator moves the arm counterclockwise so that it is over the desired number on the outer rim. Then, rotating clockwise back to zero, a spring-ratchet attached to the arm engages a tooth on the inner disc and rotates it through the number setup. When the inner disc goes a full revolution, a carry mechanism advances the middle wheel one unit.
There is also a thin iron bar coming off of the side of the crossbar. The other end of this bar fits in the engraved wedge-shaped grooves around the inner circumference of the topmost brass disc. This bar permits the crossbar to be rotated only counterclockwise.
Biography of Aaron Hatfield
Aaron “Aron” L. Hatfield was born in Lewisburg, Pennsylvania in 1819, the son of Peter (1790-1846), and Anna Hatfield (-1871). Aaron had a younger brother, Lewis (1834-1879).
Aaron Hatfield is listed in the 1850 US Census as still living in Lewisburg, Pennsylvania. By then he was 31 years old, worked as a watchmaker and jeweler, and had a wife—Susanna (Kleckner) Hatfield (1826-1877) and two children. In 1856 Hatfields moved to Clyde, Ohio, and the next US Census of 1860 lists Aaron L. Hatfield as 40 years old, born in Pennsylvania, and living in Green Springs, Sandusky, Ohio. By then he worked as a photographer (ambrotypist). No family is listed. The 1880 US Census lists Aaron L. Hatfield, 61 years old, widowed, and a watchmaker, living in Constantine, St. Joseph County, Michigan. Aaron and Susan had several children, but most of them died young: Sallie Ann (died in 1854), Zachary T., and Anthony Kleckner (1848-1857), later they had a daughter, who survived— Ida A. (1855-1941).
Aaron Hatfield died on 4 December 1898, in Three Rivers, Michigan, where he held a small jewelry and musical instruments store. Last years of his life he was living a secluded life above his store.
In addition to the patent for the above-mentioned machine for adding numbers, Aaron Hatfield took out several other US patents. The US patent №103327 was for an improvement in pruning shears and was taken out in 1870, when Hatfield was living in Clyde, Ohio. The next patent №143759, was for an improvement in pumps and was taken out in 1873, when Hatfield was still in Clyde. The last patent №199705, was for an improvement in bag holders and was taken out in 1878, when he was living in Constantine.