William Lang was a businessman (founder of William Lang Company of Brooklyn, manufacturer of metal goods) and prolific inventor from Brooklyn, New York. He patented a wide range of goods, including a windows shade pull, a speed indicator, a fife, a curtain-pole ring, a box fastener, a watch case, a coin-controlled vending apparatus, a pocket lighter and a tuning-peg. Interestingly for us, among his patents, there is one for a simple adding machine (U.S. Patent Nr. 431365 from 1 July 1890.) The witness of Lang’s patent was John Alonzo Straley (1859-1907), a prominent New York lawyer.
The adding device of Lang (see the nearby image) was produced and distributed under the name Sales Register by the company of Edward John Hoadley (1848-1927), a businessman from Hartford, Conn, a manufacturer of specialties in confectionery and a holder of quite a few patents.
The Sales Register of Lang was a small tin and brass device with an overall measurement: 2.2 cm x 17.8 cm x 7.6 cm. The device has a tin case painted yellow and green on top and red around the edge. The top of the case has four wheels drawn on it, each of which has the digits from 1 to 9 drawn around the edge.
The digits go clockwise for the first and third circles (marked Cents and Dollars and counterclockwise for the second and fourth circles (marked Dimes and 10 Dollars). At the top of the circles, at the zero position, is a window that reveals a rotating disc below. The discs are rotated using thumbscrews that protrude from the back of the instrument (see them in the upper image). An arm on top of each circle points to a digit on the wheel. The discs advance when they are rotated in the direction of increasing digits and remain fixed when the arrows are moved back to zero.
The machine is a cheap and convenient adding device for store-keepers and others who have to add quickly small figures in filling the orders of their customers, being useful instruments in the hands of boys and girls who wait on customers and make up the bills for the same. As the entire device is made of sheet metal, it can be furnished at a very low price and is consequently within the reach of everyone requiring the assistance of such a machine.