Cardboard models of Second Order Surfaces, 1901.

This set of seven cardboard geometrical models on wooden stands was made by Martin Schilling at the Munich Workshop set up by Felix Klein (1849-1925) and Alexander von Brill in the 1870s to produce a wide variety of surface models. 'Second Order' means there are squared terms in their equations. This type of model could be distorted into an infinite number of shapes by gentle manipulation. During the late 19th and early 20th century, there was an interest in geometric model making, particularly in Germany.