Quantifications of the Secondary Qualities, Heat and Cold, on the Earliest Scales of Thermoscopes

Abstract

Abstract While scaled thermoscopes were developed only at the beginning of the seventeenth century, the medical tradition had already started to quantify some secondary qualities towards the end of sixteenth century. However, degrees of heat and cold were only meaningful in connection with Galenic-Aristotelean ontology, consisting of elements, temperaments and degrees of the four humours. The first graduated thermoscopes transformed the prevailing conceptualizations of heat and cold. By delegating some specific senses of heat and cold to an external contrivance, together with the evolution towards a linear numerical scale, these qualities became objectified as observable phenomena. The degree of expansion and compression of air, and later liquid, became an observable measure of temperature and narrowed down the existing conceptualizations of temperature. The paper also discusses the three types of scale that were used in the early thermoscopes between 1610 and 1640.