Map of the Mississippi River south of Clarksville with details of the area around Hamburg, Illinois. Complied from survey of Upper Mississippi River in 1878 and 1879 under direction of Bvt. Lt. Col. F. U. Farquhar, U.S.A. Major, Corps of Engr's; with additions from notes and surveys done under the direction of Bvt. Maj. Gen'l G. K. Warren, U.S.A. Major, Corps of Engr's, Col. J. N. Macomb, Corps