Application of Special Variance Estimators to

the basic National horizontal and vertical networks of geodetic control and provides governmentwide leadership in the improvement of geodetic surveying methods and instrumentation, coordinates operations to ass ure network development, and provides specifications and criteria for survey operations by Federal, State, and other agencies. NGS engages in research and development for the improvement of knowledge of the figure of the Earth and its gravity field, and has the responsibility to procure geodetic data from all sources, process these data, and make them generally available to us ers through a central data base. NOAA Technical Memorandums and Some special NOAA publications are sold by the National Technical In­ formation Service (NTIS) in paper copy and microfiche. Orders sh ould be directed to NTIS, 5285 Port Royal Road, Springfield, VA 22161 (telephone: 703-557-4650). NTIS customer charge accounts are invited; some commercial charge accounts are accepted. When ordering, give the NTIS accession number (which begins with PB) shown in parentheses in the following citations. Paper copies of NOAA Technical Reports that are of general interest to the public, are sold by the (telephone: 202-783-3238). For prompt service, please furnish the GPO stock number with your order. If a citation does not carry this number, then the publication is not sold by GPO. All NOAA Technical Report� may be purchased from NTIS in hard copy and microform. Prices for the same publication may vary between the two Government sales agents. Although both are nonprofit, GPO relies on some Federal support whereas NTIS is self-sustained. a network of about 1,300 designated libraries. Requests for borrowing Depository Library material may be made through your local library. A free listing of libraries currently in this system is available from the Library DiviSion, reprinted annually, 12 pp (PB265442). National specifications and tables show the closures required and tolerances permitted for first-, second-, and third-order geodetic control surveys.1). Fifty-four papers present the progress of the new adjustment of the North American Datum at mid­ point, including reports by participating nations, software descriptions, and theoretical considera­ tions. Use of climatological and meteorological data in the planning and execution of National Geo­ detic Survey field operations. bility, pertinence, uses, and procedures for using climatological and meteorological data are discussed as applicable to NGS field op erations. Final report on responses to geodetic data questionnaire. 39 pp (PB254641). Responses (20%) to a geodetic data questionnaire, mailed to 36,000 U.S. land surveyors, are …