Allan Stacey of Chelmsford, ON writes:

For some time I have been researching Middleton Crawford, an inventor with a varied focus. His earliest invention was a cockle machine (US patent #285,344 patented Sept. 18, 1883 for a grain cleaning machine) while he was a resident of Wiarton, Ontario. Other inventions followed until July of 1891 when he patented a grinding and amalgamation mill for the processing of gold bearing ore. (US Patent #11,180 July 28, 1891) This first mill employed heavy steel balls circulating over a round trough, while a subsequent variation replaced the steel balls with rollers (Great Britain Patent #16,219 Aug. 25, 1894). In my research of the Belmont mine (Cordova) I note that the South African General Exploring and Mining Company of London England took up an option on the mine circa December 1891 and installed four Crawford mills in a mill plant in the village of Marmora. The company purchased the patents for $500,000.

Another note dated winter 1892 says the four small ball mills (3 tons per day per mill) were set up in a sawmill that was idle during the winter. Ore was teamed by sleighs from the mines to the mill during the winter months.