This folder covers the period December 1891-October 1892, with the later months noticeably less complete than earlier months. The folder consists mainly of "Test Reports," a standard form for reporting daily operations at the Ogden mill. Such reports contain running times, concentrate percentages, magnet hours, tonnage of ore delivered to the stock houses, and average hourly feed to the separator. Regularly attached to the report are supplementary remarks addressing the causes of mill stoppages and the results of coarseness tests. Approximately 40 percent of the documents have been selected. Courtesy of Thomas Edison National Historical Park.