Not all Model 1857 movements manufactured by Waltham feature Bingham’s patent dust ring.
Even when originally fitted with a dust ring, it was often discarded or lost by watchmakers while the movement was in for service.
Fortunately, there is an easy way to determine if the patent dust ring was originally fitted on a Model 1857 movement.
A small screw near the perimeter of the pillar plate serves as a guide pin when the dust ring is installed. If this screw is present or a small hole visible, the movement was originally fitted with a dust ring. Frequently, there is also evidence of the spurs rubbing on the edge of the upper plates while the dust ring was installed and removed (see darkened area on the upper plate in the accompanying image).