Between 1839 and 1853 the French mathematician Théodore Olivier created string models to teach and demonstrate descriptive geometry, some of which could be manipulated. He was a student of French mathematician Gaspard Monge, who invented descriptive geometry and was already illustrating his ideas with rudimentary string models. Photo above: intersection of two cylinders.

*Sources:*

- Nicholas Mee (2013) Strings, Surfaces and Physics.
- Photo above taken in the Musée des Arts et Métiers in Paris, see flickr set.
- Other models at exposed at the Canada Science and Technology Museum (but not in such a good shape!), see flickr set.

Added by:

**Pierre Dragicevic**. Category: Physical model Tags: geometry, mathematics, mechanical interaction, teaching