This is a Lewis, an instrument from Operative Masonry.
It is an iron cramp that is inserted into a cavity prepared for that purpose so that large stones may be raised to any height
by rope and pulley. The stone is then placed in its proper position. In the English system of Masonry, the Lewis is found
on the tracing-board of the Entered Apprentice, where it is used as a symbol of strength, because by its assistance the heaviest
of stones can be lifted with comparatively little exertion. The son of a Mason in England is called a "Lewis", because it
is his duty to support the sinking power and aid the failing strength of his father.
Is there a Lewis living in your house? Tell him about the Craft!