Part Of Southern California Atlas Sheet No. 73 (A). Expeditions of 1875 & 1878 Under the Command of 1st. Lieut. Geo. M. Wheeler. Corps of Engineers, U.S. Army. Executive Officers & Field Astronomers: 1st. Lieut. C.W. Whipple, Ordnance Corps. and 2nd Lieut. Willard Young, Corps of Engrs. Topographical Assistants: Frank Carpenter and William A. Cowles. U.S. Geographical Surveys West Of The 100th Meridian.