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
`Artiflex' dental pedestal unit by Siemens-Reiniger Werke A.G., Erlangen, Germany, 1951-1952. `Artiflex' dental pedestal unit on plywood stand Dentistry 1951-1952