An iron dovetailed tenon, made in sections, which can be fitted into a dovetail mortise; -- used in hoisting large stones, etc.
An attachment for lifting heavy stones, consisting of a sectioned dovetailed iron piece that fits into a dovetail opening in the stone.
A Lewis is a steel lifting device used by Stonemasons to lift large stones into place with a crane, chain block or winch. It is inserted into a specially prepared seating in the top of a stone, directly above its centre of mass. It works by transferring the stone's own weight into leverage on the seating.