Gunner's callipers; brass with iron tips

Gunner's callipers; brass with iron tips, for measuring external and internal diameters from3/4" to 7 1/2"; inscribed: Dominucus Lusuerg, late 17th or early 18th century

This instrument is for measuring the bore of cannons and the diameter of cannon ballsis inscribed with the name 'Dominicus Lusuerg' who lived in Rome from 1694 to 1744. it is made of brass. The scale graduations are proportional to the cubes of the diameters so that direct reading of the weights of the balls measured are obtained. the word ferro on the scale indicates that it was intended for measuring cannon balls of iron.