Ruth Vollmer was a designer and sculptor fascinated by mathematical forms and the principles of geometry. In Archimedean Spiral, 1973, she presents the spiral form named after the Greek mathematician, carefully mapped in red on ‘x’ and ‘y’ axes, the spacing emphasised by green concentric rings. Archimedean spiral shapes are seen occasionally in ammonite shells. Vollmer had a particular interest in the forms of shells and in 1973 had a solo show at the Betty Parsons Gallery in which she showed several works dealing with the spiral. Having spent much of her earlier career designing toys and models for children and window displays, her sculptures were often made with materials experienced in these roles and were interactive and made to be touched.

Sol LeWitt, a friend who shared her passion for mathematical ideas, admired her work, stating that it was not sculpture but ‘ideas made into solid forms. The ideas are illustrations of geometric formulae; they are found ideas, not invented, and not changed’.