Santorio Sanctorius, Italian physician, 1728.
© Science Museum / Science & Society Picture Library
Santorio Sanctorius (1561-1636) portrayed in an engraving from 'Ars de Statica Medicina'. Sanctorius was an Italian physician and the founder of quantitative measurement in medicine. He was the first to use a thermometer to measure body temperature, and also invented various instruments, including a hygrometer and a water-bed.