Nash Logoscope Mark III in case, an aid to differential diagnosis in 'slide-rule' form, developed by Dr Firmin Nash, manufactured by Medical Data Systems, Nottingham, England, c.1962 Nash Logoscope Mark III circa 1962
Nash Logoscope Mark IV in box, an aid to differential diagnosis in 'slide-rule' form, developed by Dr Firmin Nash, manufactured by Medical Data Systems, Nottingham, England, c.1965 Nash Logoscope Mark IV circa 1965