“Rewlestone” plumb level

[mklotz]

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This is a modern copy (just done) of a very ancient levelling device and in the medieval carpenter’s toolbag, it was called a “rewlestone” viz. “rule” & “stone”.
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"very ancient" indeed. Egyptians building the pyramids 5000 years ago used something very similar. They referred to the cord position on the cross bar rather than the bob pointer. This allowed them to scribe other lines on the crossbar for frequently needed inclinations. (They had learned the hard way that if the pyramid slope was too large, very bad things would happen.)