Barter/Trade or sale. c1914-1917 Calculating machine. Brass and wood. In original dovetailed wooden box. No lid. This is a precursor to the linear slide rule. It was used extensively by civil engineers etc. from the 1890's thru to the 1930's. Made in England by Stanley and imported and assembled in US. Model # 4012. Arguably the most sought after Thatcher Calculating machine made. In need of much work but still a great collectors piece. Asking $150 obo (OR BARTER/TRADE) Call me or email with any reasonable offers. Cell is faster: 202-615-7410. Location: 20012 it's NOT ok to contact this poster with services or other commercial interests dc