Brass Depthing Tool

Three iron legs support the brass frame with three-clamp work holder, upright pivoted center with brass arm for contact with the calibrated snail, engraved, John Downes, London.

A depthing tool measures the correct distance for the wheels and pinions to be calibrated to properly engage, and to prevent butting. Butting – when the tooth of a wheel and the leaf of a pinion hit each other instead of advancing – is one of the major reasons that a clock will stop.