american carpenter rulera vintage folding carpenter's ruler from the united states. total length measures 24 inches. the ruler folds into four and has a small blunt nail notch to help it hold together when closed (see third image). made of wood and brass ends. rulers have a long legacysupposedly some were even found Roman ruins! in the 1850s, the folding rule was popularised by Anton Ulrich for carpenters and tradespeople, allowing them to have a portable ruler with which to