The Story of
the Automaton


Putting It In Motion...

For Teachers


For Students

For Reference


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The heart of the automaton's writing and drawing operation is actually a mechanical "read only memory" in the form of an array of disk cams rotating on a common shaft to drive the right hand of the figure. The information contained in the undulations of the selected set of cams is picked up by three cam followers linked to the doll's hand to produce the required left and right, up and down, and vertical movements. Maillardet's Automaton contains a total of 72 operating cams which control the movements of the right hand. Additional and far simpler cams move the left hand, head and eyes of the doll.

The cam and follower is a device which can convert rotary motion into linear motion (movement in a straight line). A cam is a specially shaped piece of material, usually metal or hard wearing plastic, which is fixed to rotating shaft. The cam can have various shapes e.g.. round, oval, heart shaped. A follower is a mechanism which is designed to move up and down as it follows the edge of the cam.

There are several different types of cams but most of these can be placed into two groups, rotary and linear. Rotary cams change rotary motion into reciprocating (backwards and forwards) motion. As the cam rotates, the follower moves accordingly. The exact distance it moves depends on the shape of the cam.

These cams are called "lobed cams" because they have additions to the circular shape known as lobes. One complete revolution of the cam is called a cycle. As the cam rotates there will be one distinct event per revolution for each lobe. The timing of the events will depend on the speed of rotation.

Cams have the ability to store information. Another way to look at cams is as the mechanical version of a computer program. The information is stored in the shape of the cam. As the cam turns, the information is retrieved by the cam follower. The follower tracks the movement of the cam's profile (shape) and reproduces the same movement for each cycle. In the case of Maillardet's Automaton, the series of cams carry out the complex programs that produce its drawings.

Going Further - Learn More About Automata and Mechanisms

If you are interested in designing your own automata, or simply understanding the workings of existing automata more thoroughly, the Cabaret Mechanical Theatre offers an excellent book entitled Cabaret Mechanical Movement for sale through their online store.

The Design and Technology Department of Deyes High School, Deyes Lane, Maghull, Liverpool has published a section called What is a mechanism ? on their website which offers students an in-depth look at the mechanics of movement.