JF Ptak Science Books Quick Post
Just a quick post here on patented mathematical tools using long wooden planks in a sliding frenzy to find displayable answers for 19th century schoolchildren and their addition problems. I know a good set of Napier's bone could come in very handy (appearing much earlier on than these instruments), but I'm just not sure what kids could learn from using these tools--like any other calculating device, early or late, they have a questionable quidity so far as appreciating the essence of numbers is concerned. That said, the drawing for the Meyers' machine is beautiful, and could no doubt lead to a number of short, noir-y stories.
Source: Google Patents, here.