Prototype logoscope, c 1953.
© Science Museum / Science & Society Picture Library
The logoscope, an aid to differential diagnosis in 'slide-rule' form, was designed by Dr Firmin Nash in the age before the personal computer. It was an attempt to provide GPs with a diagnostic tool that would provide a broad, but accurate, list of possibilities for them to consider along with those arising from their own diagnostic skills. 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 It also acts as an interesting precursor to the computer diagnosis aids which superceded it.