ESHS/HSS Annual Meeting

“An Instrument which Tells us what the Body Feels”: The Kata-Thermometer and the Measurement of Comfort

• In Event: Measurement and Instrumentation

English Abstract

While histories of thermometry are typically narrated as a continuous movement away from human sensation toward objective measures, this paper traces an alternative lineage with a more entangled relationship between instrumentation and human subjectivity. Invented by the London physiologist Leonard Hill, the kata-thermometer combined a dry-bulb thermometer (to measure heat loss through convection and radiation) and a wet-bulb thermometer (for evaporative heat loss). I argue that the kata-thermometer reorganised twentieth-century scientific research on ventilation in three important ways. First, it helped Hill pivot ventilation research away from an emphasis on the biochemical quality of air to its thermal properties. Second, Hill successfully argued that the use of both thermometers meant his instrument could adequately model heat loss in human bodies. This helped launch a research programme with a two-way connection between physics and physiology: the body could now be modelled using thermodynamics, but the validity of new measures still depended on subjective assessments of thermal comfort by test subjects. Third, although the wet-bulb thermometer had already been in use, earlier use-cases simply treated the surrounding air as a background condition enabling evaporation. The kata-thermometer, however, treated the velocity of air as a quantifiable variable that needed to be accounted for. This meant it had to be tested against existing anemometers (instruments that measure wind velocity), and once successfully validated, allowed the incorporation of wind speed into subsequent measures of heat loss and comfort. The kata-thermometer therefore served as a significant conjuncture and pivot for twentieth-century physical, physiological, and environmental research.

Author

• Sharad Pandian, Princeton University