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On March 21, 1840, Thomas Watter sold his one-fourth interest to James Pratt for $650. In July, 1842 James Brunskill sold his one-fourth interest to Pratt and Walter MANSON. James Pratt and Walter Manson owned the controlling interest and operated the mill as Pratt & Miller for twenty-five years. (1) The mill's capacity was approximately sixty barrels daily or ninety thousand bushels annually. A stone addition to the mill increased the production to 412,500 bushels annually. Processed wheat in 1855 sold for between forty and sixty cents per bushel in GOLD.
On March 21, 1840, Thomas Watters sold his one-fourth interest in the mill to James Pratt for $650. In July, two years later, James Brunskill sold his one-fourth interest to James Pratt and Walter Manson. The operating firm became known as the James Pratt and Company and operated under the name until 1870. It was Pratt and Manson who coined the name "Rockdale Mills" for their business and replaced the original log building with a frame structure four stories high. (3)
The partners in the firm continued to change. Walter Manson on September 1, 1868, sold three-eighths interest to Henry Meyer and John H. Deggendorf for $6,625. In 1870 a lawsuit resulted in the sale of the mill and other property by a referee to Adam Twaits for $11,000. In 1874 Twaits sold it for $18,000 to William G. Watters. The following year Watters sold a three-eighths interest to Richard Waller for $8,500. Three years later Waller obtained another three-eighths interest for $6,655. The mill burned to the ground in 1878, but the site was purchased by Thomas Watters, Jr. He rebuilt the mill, in which his grandfather had been an original partner, and changed the name to the South Dubuque Mill. Watters obtained a three-eighths interest for $2,050, and the same year A. W. Hosford acquired a three-eighths interest which he sold to in 1885 D. B. Cooley. On October 1, 1885 Cooley sold his interest to J. F. Gandolfo who with partners operated the mill for a number of years. With repairs estimated at five thousand dollars, the mill was again producing such brands of flour as "Crown Jewel," "Gold Crown," and "Choice Patent" at a rate of one hundred ten barrels daily. During the last years the mill was operated it was owned by the Home Milling Company. When the mill closed in 1905, John William MANSON, then associated with the IOWA HOUSE FURNISHING COMPANY, was in charge of operations.
The success of the Rockdale Mills broke the monopoly of St. Louis on trade along the Upper Mississippi. Flour equal in quality to the St. Louis, Missouri, variety was produced in Rockdale for one-fourth the cost. This success led to the establishment of other mills. For a time Dubuque enjoyed a monopoly on everything in the provision market for settlers north into Minnesota. Dubuque County continued its control over the Minnesota flour trade until 1858 when Red Wing, Minnesota, became an exporter of flour rather than a buyer.
Dubuque mills, including Rockdale, developed eastern markets for flour until July 4, 1876, when the ROCKDALE FLOOD temporarily ended the milling business in Rockdale during a night of terror.
The Rockdale mills were destroyed by fire late on December 31, 1878. (4) The blaze was caused by an explosion of gas generated by the middlings purifier used.Joseph J. NAGLE to a corporation that operated the plant until 1915 when competition led it to be shut down. The milling machinery sold, and the building was used for storage. by the Twin Valley Dairy and briefly used as the Moes Dairy barn until 1927 when it was destroyed by fire.
1. "Rockdale," Dubuque Herald, July 30, 1876, p. 4. Online: https://news.google.com/newspapers?nid=uh8FjILnQOkC&dat=18760730&printsec=frontpage&hl=en
4. "A New Year's Blaze," Dubuque Herald, January 1, 1879, p. 4. Online: https://news.google.com/newspapers?nid=uh8FjILnQOkC&dat=18790101&printsec=frontpage&hl=en
Oldt, Franklin T. History of Dubuque County, Iowa. http://www.ebooksread.com/authors-eng/franklin-t-oldt/history-of-dubuque-county-iowa-being-a-general-survey-of-dubuque-county-histor-tdl/page-20-history-of-dubuque-county-iowa-being-a-general-survey-of-dubuque-county-histor-tdl.shtml