Results of Spirit Leveling in Indiana, 1897 to 1911, Inclusive (Department of the Interior, United States Geological Survey, Bulletin 555)

51 pp. Illustrated with one black-and-white plate. Includes: Introduction; Scope of the Work; Personnel; Classification; Bench Marks; Datum; Topographic Maps; Precise Levling: Bloomfield, Bloomington, Burns City, Clay City, Heltonville, Jasonville, Oolitic, Paoli, and Terre Haute Quadrangles (Clay, Greene, Lawrence, Owen, and Vigo Counties); New Albany, Paoli, and Salem Quadrangles (Clark, Floyd, Lawrence, Orange, and Washington Counties [Ind.] and Jefferson County [KY]); Primary Leveling: Boonville, Degonia Springs, Huntingsburg, Leopold, Owensboro, Petersburg, St. Meinrad, Tell City, and Velpen Quadrangles (Daviess, Dubois, Gibson, Pike, Spencer, and Warrick Counties); Evansville, Hauptstadt, Newburg, New Harmony, Princeton, and Vincennes Quadrangles (Gibson, Knox, Posey, and Vanderburg Counties); Kosmosdale, New Albany, and Prospect Quadrangles (Clark, Floyd, and Harrison Counties); Bloomington Quadrangle (Greene, Monroe, and Owen Counties); Clay City Quadrangle (Clay, Owen, and Vigo Counties); Toleston Quadrangle (Lake County); Danville Quadrangle (Warren County); Appendix A: Elevations Adjusted by the Coast and Geodetic Survey from Precise Leveling; Appendix B: Primary Leveling by the United States Corps of Engineers; Index. "Spirit leveling, the oldest method of measuring subsidence and uplift, derives its name from the primary tool utilized in the process - the spirit level. Spirit leveling is a precise way to obtain data for smaller land areas, and is commonly used along road, railroad tracks, aqueducts, and canals. Spirit leveling was once a common method of determining elevation. Before the advent of the satellite-based Global Positioning System (GPS) in the 1980s, the most common means of conducting land surveys involved either the theodolite or, since the 1950s, the geodimeter (an electronic distance-measuring device, or EDM). When only vertical position is sought, the spirit level has been the instrument of choice. The technique of differential leveling allows the surveyor to carry an elevation from a known reference point to other points by use of a precisely leveled telescope and graduated vertical rods. Despite its simplicity, this method can be very accurate. When surveying to meet the standards set for even the lower orders of accuracy in geodetic leveling, 0.05-foot changes in elevation can be routinely measured over distances of miles. At large scales, leveling and EDM measurement errors increase. When the scale of the survey is small (on the order of 5 miles or less) and the desired spatial density is high, spirit leveling is still commonly used because it is accurate and relatively inexpensive. Large regional networks warrant use of the more efficient Global Positioning System (GPS) surveying for differential surveys." - United States Geological Survey