Ready reckoner with cursor Ready reckoner with cursor, plastic, for temperature-pressure relation of ICI refrigerants. Materials: plastic (unidentified) Object Number: 1988-308/1 type: ready reckoner Image © The Board of Trustees of the Science Museum
Plastic case for ready reckoner Plastic case printed "Unitor Ships Service. Refrigerant Slide Rule", for ready reckoner with cursor. Materials: plastic (unidentified) Object Number: 1988-308/2 type: case Image © The Board of Trustees of the Science Museum
