George Bernard Grant was born in 1849 in the state of Maine in the USA. While studying engineering and having to carry out lengthy calculations of logarithmic and other tables, he had the idea of constructing a calculating machine based on Charles Babbage's difference machine. The machine was unveiled at the 1876 Centennial Exhibition, a world's fair celebrating the 100th anniversary of the US Declaration of Independence, and was possibly the largest calculating machine ever built in the world at the time.
Grant went on to build and patent other very interesting calculating machines, one of which he called the Centennial calculating machine. This was intended to herald particular advances in computing technology. The Centennial calculating machine from 1877 is a four-species calculating machine, which is presented in the following video. Like all of Grant's machines, it had only modest commercial success, but was very robust and reliable.

In their detailed video, computer science students Evelyn Lippmann and Tim Vellmer show in detail how this machine worked and explain the mechanics in all their detail using a 3D model. We hope you enjoy watching our new calculating machine of the week!