Very fine 'as found' condition. Rare square with a deep clear D. M. LYON & CO WARRANTED (Newark NJ) stamp. Eric Benson at chapticowood.com notes that no squares are known with this stamp. Absolutely no rust or pitting on the blade. This square will absolutely pop with a light cleaning of the blade. The blemish in the wood near the base of the handle looks like a flaw in the rosewood but may also be an abrasion. Brass hexafoil escutcheon, fence, and tool rest are clean and excellent. Large, rare, and spotless, this square has everything going for it. Top shelf! A & T CRANE stamped in the rosewood on the back side. This partnership may also be of interest as I see very very few 'partnership' owner's stamps.
Check out chapticowood.com for fantastic research on early American square and bevel makers!