How did an operative mason lift a heavy stone straight up and lay it down level without getting his rope caught underneath? By using a Lewis. The term Lewis or Lewis Appliance is from the eighteenth century and refers to a type of grapple used by stonemasons and known to have existed from the time of the Romans and most probably much earlier. Historically the Lewis was originally made of bronze and later of iron. The Lewis is still used today and can be of several forms. One of those forms is called “St. Peter’s Keys”, taking its name from its resemblance to keys on a ring. Examples of this type were used in the building of the Duomo Cathedral (comp. 1436) in Florence Italy, designed by F. Brunelleschi (1377-1446). Tourists can see an example of a Lewis used in the construction still hanging on a nail there today.