Nash Logoscope 82E in case, an aid to differential diagnosis in 'slide-rule' form, developed by Dr Firmin Nash, manufactured by Medical Data Systems, Nottingham, England, 1972-1975

The logoscope aided ‘differential’ diagnosis in ’slide-rule’ form. It was designed by Dr Firmin Nash in the age before the personal computer. It attempted to be a diagnostic tool providing a broad, but accurate, list of possibilities for GPs to consider alongside their own diagnostic skills. Each plastic strip has a different symptom, for instance ‘swelling on the bone’ or ‘hiccups’, and is marked by a number of black lines. The GP collects the symptoms the patient has from the box and places them on the plastic slide rule. He or she then uses the magnifier to see where the lines match up and reads the diagnosis from the list on the left-hand side.

Personal computers became widely available by the time the logoscope reached final design, although they sold well in Japan. Devices such as this that ‘mechanise’ diagnosis have not usually caught on. As a museum object, it is a fascinating symbol of the tension between the art and the science of medicine. It is also an interesting precursor to the computer diagnosis aids which superseded it.