An antique mechanical engine indicator set manufactured by H. Maihak AG of Hamburg, Germany, and distributed in the United States by the Bacharach Industrial Instrument Co. of Pittsburgh, Pennsylvania. This specific model is identified on the circular dial face as a Boettcher's Leistungszaehler, a specialized integrating indicator designed for the continuous recording and measurement of engine power. The instrument is constructed from nickel-plated brass and steel and features a recording drum, a piston assembly with an external spring, and an integrated counter mechanism. The instrument body is stamped MAIHAK and numbered 12197. A secondary component is marked C-1465, and the spring collar is engraved 100 lbs piston 1/2. The circular dial face contains the text H. MAIHAK Aktiengesellschaft HAMBURG and Boettcher's Leistungszaehler around its perimeter. The set is housed in its original fitted mahogany case with a brass distributor plate on the interior lid reading BACHARACH INDUSTRIAL INSTRUMENT CO. PITTSBURGH, PA. The case includes various accessories including multiple spare springs in wooden blocks, a large steel wrench, threaded metal fittings, and small components stored in specific compartments.