The mining mill was built in 1972-73 to replace an earlier one after its roof collapsed due to heavy snow. The machinery on display here was used in the gold mining operations of the 1800s. A portable boiler built by the Ames Iron Works of Oswego, New York, was used to generate steam pressure to run an engine and connected to a one-cycle Nagle Engine, built around 1900. The Nagle engine produced up to 25 horsepower at 2200 r.p.m., which was sufficient power to operate the 5-stamp mill. A stamp mill was used for crushing ore. A leather belt would have connected the flywheel to the line shaft. The steam engine turned a line shaft (consisting of pulleys on a metal shaft) at a constant r.p.m. to run the mill's machinery at the correct speeds. Each piece of equipment had to be belted to a properly sized pulley on the shaft.
At the Upper Moose Mine, museum founder Leon Snyder noticed two steam boilers dated 1867 among the decaying equipment and decided they would be perfect for South Park City. The boilers had been slated to go to the Smithsonian Institute until it was decided that getting them off the mountain would be too costly and difficult. However, that did not deter Mr. Snyder. He contacted Arthur Flannigan, a Realtor and former mining engineer from Alma, and they concluded that they could get the job done with the proper moving equipment. Their efforts were successful. One of these boilers is located in the mill building. The other boiler rests at the north end of South Park City facing Mt. Bross—the very mountain where it had served those early miners many years ago.
