On 18 June 1867, Alexander Davies (1832-1900) from Cleveland, Ohio, received a US patent Nr. 65883 for computing machine—a slide bar adder, quite similar to the earlier adding device of George Fowler, patented in 1863. The patent model of the device (see the lower photo) survived to our time (up to 1880, the US Patent Office required inventors to submit a model with their patent application) and is kept now in the collection of National Museum of American History in Washington, D.C.
Let’s examine the adding device of Davies, using the patent application (see the lower drawings).
The adding device of Davies was a metal, wood and paper instrument with overall measurements: 4 cm x 21 cm x 8.7 cm. The machine is marked on the left side: Computing Machine A.W. Davies.
The device has five continuous endless chains (metal bands), thus corresponding with the rows of figures on the board, which are counted from the top downwards, as units, tens, hundreds, thousands, and tens of thousands, as indicated by the lettering between the opening in the right section of the cover or stop-plate (marked with J’ on the patent drawing). The chains move in slots across a wooden frame (marked with A), passing around the wheels B and B’. Flat pieces of brass cover the top of the frame on the right and the left, keeping the bands in their slots. The chains (bands) are made up of small flat squares of metal, with nine squares silver-colored and the tenth one brass. Each square has a hole at the center for inserting a peg.
Strips of paper attached between the bands are numbered from 1 to 9. Moving a band to the right turns the corresponding wheel clockwise. The edge of this wheel, which is covered around the edge with a paper marked with the digits from 0 to 9, is visible through a window in the right piece of brass. The number shown increases as the wheel turns. A lever on the left side disengages (resets) the fourth and fifth columns.
The carry mechanism, activated when a wheel passes 9, was implemented by a pawl (marked with G on the patent drawing), attached to a cam (marked with H), which engages in the notches of the wheel next in order, causing this wheel to move the distance of one link, adding one to the higher position.
Biography of Alexander Davies
Аlmost nothing is known about the inventor of this adding device— Alexander Davies.
Alexander W. Davies was born in 1832, and died on 14 March 1900 in Cleveland, Ohio. We know that he worked many year as a clerk, car agent, and accountant for several railroad companies in Cleveland between 1863 and 1900. He was a holder of two other US patents (US455197 and US456650) for inventions relating to recording the mileage traveled by railroad cars (car mileage register and report).
Alexander W. Davies married to Susan Harriet (Weeks) Davies (1832-1912), the daughter of David and Harriet Lucy (Webster) Weeks, the family came to Cleveland, OH, in the early 1850’s from Bennington, VT, where the Weeks family had resided since 1763.