Monromatic Model 8N-213 (calculator)

Beige coloured Model 8N-213 electro-mechanical rotary calculator made by the Monroe Calculating Machine Co, Orange, N.J., USA about 1955, with plastic cover and instruction manual. Used at Frederick Braby & Co Ltd, Ashton Gate, Bristol until about 1975, for design calculations for steel framed buildings and pressure vessels. The donor was formerly the works manager.