Johannes Kepler and the Exploration of the Weight of Substances in the Long Sixteenth Century

Abstract

Abstract Numerous early modern experimentalists, including Galileo Galilei, Francis Bacon and Thomas Harriot, viewed one seemingly humble principle – that at a given volume, different substances can be identified by their particular weight, or specific gravity – as a fundamental key to the understanding of nature in general. Johannes Kepler’s Messekunst Archimedis of 1616 contains a striking summary of the experimental research on specific gravities in the long sixteenth-century. Counting himself amongst an extensive list of authors interested in this problem, Kepler mentions not only natural philosophers or mathematicians interested in Archimedes. His account surprisingly includes humanists, instrument makers, antiquarians and assayers. Received histories of specific gravities often focus on antecedents of modern disciplinary concepts and methodologies, where instead, Kepler’s account suggests the existence of a heterogeneous group of early modern experts involved in experiments on the quantification of matter, at the intersection between the history of science, practical mathematics and the humanities.