Like what I make? Want fewer sponsorship ad reads? Consider contributing to my Patreon at https://patreon.com/OurOwnDevices Produced by the Wolverine Toy Company of Pittsburgh in the 1950s and marketed as a children's toy, this is a very basic mechanical calculator based on a simple stepped gear mechanism, and is capable only of addition. Nonetheless, it is a good introduction to the design of mechanical calculators, which became very sophisticated before the advent of electronics.