from survey made between the 14th & 27th August 1856 by assistant John R. Mayer, under the direction of Brevet Lieut. Col. J.D. Graham, Major, U.S. Top. Engineers. Superintending Engineer of Lake Michigan Works
from survey made in October 1856 by assistant John R. Mayer under the direction of Brevet Lieut. Col. J.D. Graham, Major U.S. Top. Engineers. Superintending Engineer of Lake Michigan Works