Locke Adder

"The Locke ... patented December 24th 1901 from Kensett Iowa, ... is made of embossed tin and is quite colorful, with the sliding bars painted in alternating reds, greens and yellows. It is similar to the Fowler, except that its readout is neither on the top nor bottom of the moving bars, but rather on the side facing the user: the fixed bars are scooped out at the right hand edge just after the 9 so that the result can be viewed. Also, instead of having holes for a stylus, it has raised bumps. Thus only your fingers are required to operate it. The numbers run in the opposite direction of the Fowler."

Robert K. Otnes

Source: Robert K. Otnes, "Sliding Bar Calculators." ETCetera No. 11, June 1990.

Link to the Excelsior Adding Machine

X-Number World