Notes on Cataneo's Scale, Some Gunners' Daggers and a Gunners' Rule

Abstract

Cataneo's scale, published in 1571, relates the weight of shot to the internal muzzle diameter of guns ranging between 0.04–0.21 m. Plots of calculated shot density versus muzzle diameter suggest that diameters of 0.10 m and above apply to iron shot and those below apply to lead and lead/iron composite shot. Similar plots are used to compare Cataneo's scale with other contemporary scales and with scales engraved on the blades of five Italian gunners' daggers dating to around 1650. Variations and errors in the daggers' scales might suggest a symbolic rather than a practical role; nevertheless there is remarkable consistency with Cataneo's scale in the shape of the plots in spite of the considerable length of time after its publication. A simple wooden scale from the Spanish Armada ship La Trinidad Valencera also confirms to Cataneo's general pattern although there appears to be a fundamental error in its mathematical construction.