# Introduction

Several early modern mathematical instruments were based on numerical determinations of specific gravities of substances.This is for instance the case of a group of instruments intended for artillers and gunners. The determination of the proper caliber of cannonballs of different materials for a given quantity of gunpowder was a typical problem for artillerymen. These calculations were quite complex, given the great variety of weapons and standards. However, these instruments allowed for the quick finding of calibers through the use of graduate scales based on specific gravities.

The scales of these instruments preserve and register numerical values that are alternative to those traditionally provided by tables in learned treatises. A systematic investigation of these values can give an original and still unexplored set of data, particularly for the early sixteenth-century –when tables of specific gravities were not yet available.

This project will measure and record numerical scales of early modern instruments, in collaboration with the Mathematisch-Physikalischer Salon in Dresden, the Museum of the History of Science in Oxford, Museo Galileo in Florence, and the Deutsches Museum in Munich. Data from mathematical instruments and further analysis on it will be periodically published here.

Current work regards the instruments of the Mathematisch-Physikalischer Salon in Dresden (right). With the help of the curators of the Salon, we developed methodologies and best practices for the direct measurement of scales of delicate and rare historical instruments.