1. The basic principles of geodesy are presented in an elementary form. The formation of geodetic datums is introduced and the necessity of connecting or joining datums is discussed. Methods used to connect independent geodetic systems to a single world reference system are discussed, including the role of gravity data. The 1983 edition of this publication contains an expanded discussion of satellite and related technological applications to geodesy and an updated description of the World Geodetic System.

2. The Defense Mapping Agency is not responsible for publishing revisions or identifying the obsolescence of its technical publications.

3. DMA TR 80-003 contains no copyrighted material, nor is a copyright pending. This publication is approved for public release; distribution unlimited. Reproduction in whole or in part is authorized for U.S. Government use. Copies may be requested from the Defense Technical Information Center, Cameron Station Alexandria, VA 22314.

FOR THE DIRECTOR:

                                           VIRGIL J JOHNSON
                                           Captain, USN
                                           Chief of Staff

The Defense Mapping Agency provides mapping, charting and geodetic support to the Secretary of Defense, the Joint Chiefs of Staff, the military departments and other Department of Defense components. The support includes production and worldwide distribution of maps, charts, precise positioning data and digital data for strategic and tactical military operations and weapon systems. The Defense Mapping Agency also provides nautical charts and marine navigational data for the worldwide merchant marine and private yachtsmen.

The agency is under the direction and control of the Under Secretary of Defense for Research and Engineering and its director is responsible to the Joint Chiefs of Staff for operational matters.

The Defense Mapping Agency maintains close liaison with civilian agencies of the U.S. government which are engaged in mapping, charting and geodetic (MC&G) activities. To further the advances in MC&G, the agency works with various national and international scientific and operational organizations.