Model of an Elongated Pentagonal Pyramid, Smithsonian Institution negative number DOR2014-00726

In 1966, fifty years ago, the American mathematician Norman W. Johnson, a student of H.S.M. Coxeter at the University of Toronto in Canada, published an enumeration of the convex polyhedra with regular faces. These included the Platonic solids, the Archimedean solids, an infinite family of prisms with square sides, an infinite family of antiprisms with equilateral triangles as sides, and a group of other polyhedra now known as the Johnson solids. This paper model of a Johnson solid shows a pentagonal prism with a pyramid erected on one of its pentagonal faces. It was made by Michael Berman, an amateur mathematician in Pittsburgh, who also made models of other regular-faced convex polyhedra. These models are now in the collections of the National Museum of American History.

For further information and descriptions of all of Berman’s models see http://americanhistory.si.edu/collections/object-groups/geometric-models.