Wilhelm Schickard’s calculating clock

Wilhelm Schickard’s calculating clock simulator with Scratch

Katherine Alejandra Estrada Puente

This new museum section includes one simulator of one of the most ancient calculating machines in history so the users can make use of it.

The calculating clock simulator is developed in the programming language Scratch. On its website, we can find some projects shared by its owners and they can be modified by the users. You can make comments and solve any existing error. This is possible thanks to the “reinvent” option which allows access to the source code of the project. This option is very useful either if we know how to start a new project or if we only want to see a specific action.

How the calculating clock simulator works Calculante

The next video has the objective to show the working of the simulator so the users can make their own testing. It includes an example of addition, subtraction, multiplication and division.


Wilhelm Shickard was born in Herrenberg, Germany. He was mathematician, astronomer, painter, Lutheran minister and Hebrew and Aramaic teacher. He invented the calculating clock in 1623 because he wanted to help his friend Johannes Kepler who was calculating Alfonsine tables manually.

Sadly, Shickard machine never saw the light because it was burnt in an accidental fire. Its existence was not discovered until 300 years later so it did not make any reference to the invention of the modern calculators.

This machine is formed by three independent modules. The superior module can make multiplications and divisions; the intermediate one is an adder which can add and subtract; the inferior module is a mechanism to record the results.

Note: to make turns clockwise you have to click on any of the buttons in the simulator. To make turn anticlockwise, keep pressed the left arrow in the keyboard and click on any of the buttons.

To access the simulator page in the Sractch website go to –> Calculating clock simulator

Creator of the simulator: Katherine Alejandra Estrada Puente

Tutor: Xavier Molero Prieto