After more thought on this, back then a few guys worked on their own, but with the beams there was likely a crew to lift and set. Then there was a *boy* a helper, gofer sometimes called, this sounds small enough the gofer on the ground could hoist up another box of nails or pegs via a cord thru the pulley. Or a water jug. How about the outside circumference, any marks? Was thinking in those days before tape measures or even many rulers, the pulley could have been used like a Wheelwrights travelers, as a measuring tool. Could be so if there are marks, or even a single mark, roll it along and count the turns.