Plaster model to illustrate the torsion of a rectangular prism. Plaster model to illustrate the torsion of a rectangular prism Mathematics 1876

Main part of a working model of a differential analyser constructed from the construction toy, Meccano, made by Professor Douglas Hartree and Arthur Porter at University of Manchester, England, 1934. Reconstructed by Prof. Douglas Hartree at University of Cambridge, England, 1947 Meccano differential analyser, 1947 Mathematics 1934; 1947

Hyperbolic paraboloid; a skew quadrilateral turning upon four hinges with parallel axes or pins; the lengths of the strings remain unaltered during deformation. Hyperbolic Paraboloid string surface model Mathematics 1872