Plaster cast of relief of a mason and stonecarvers at work, after marble original, on the exterior of the church of Or San Michele, Florence. The activities represented are, from left to right: i.building a wall, ii.drilling the decoration of a twisted column, iii.measuring a carved capital, iv.using a pick to carve a putto. The tools hanging behind the four figures are, from left to right: i.a braccio rule: a braccio, literally an arm, but signifying an arm's length, was a standard measure of slightly less than a yard. ii.a plumb line and set square, iii.a pair of dividers, iv.a set square