Late 19th Century to early 20th Century / Made by Martin Schilling Co. (Germany) / Plaster, iron / Formerly a collection of the Department of Mathematics, Tokyo Imperial University / Department of Mathematics, the University of Tokyo

The surface of this model is parametrized as above with a mean curvature of H=0. This surface is an example of a minimal surface containing a one-parameter family of parabolas. It is either a general form of Catalan’s minimal surface, or such a surface with an additional helicoidal form.