Main Valves of Steam-Powered Pumping Engine This is one of several hundred sheets depicting every piece of the “Ontario” steam-powered pumping engine, designed by Erasmus Darwin Leavitt, Jr. for a copper mine on the shores of Lake Superior. Detailed, annotated drawings allowed engineers and machinists to communicate about complicated machines like this engine. CHSI Inv. Number 6908b circa 1875 Erasmus Darwin Leavitt, Jr.