Intensity Meters: New Notes and Discoveries on the Invention of Early Modern Precision Instruments

The article sheds light on the invention of early modern precision instruments and their application in medicine, by analysing a neglected work by one of the Italian pupils of the physician Santorio Santori (1561–1636). This source provides vital information on Santorio’s experimental sample, and on the practical use and dimensions of instruments such as thermometers, hygrometers, pulsimeters and precision scales, showing that they also had a normative purpose: regulating the environmental factors affecting human health. The article first establishes the derivative nature of the source from Santorio’s teachings, and then contextualises the invention of precision instruments with regard to Santorio’s published and unpublished output. In the conclusions, I argue that the new instruments were meant to address the shortcomings of the traditional diagnostic rationale and are best conceptualised as ‘intensity meters’ meant to assess ‘the magnitude’ (magnitudo) of a patient’s illness in degrees.