m-q sl6”iTSv , 2-u- 4 LJ .d U. S. DEPARTMENT OF COMMERCE R. P. LAMONT, Secretary COAST AND GEODETIC SURVEY R. S. PAlTON, Dirscta Special Publication No. 160 CO ADO [ 1927 DATUM] BY OSCAR S. ADAMS Senior Mathematician UNITED STATES GOVERNMENT PRINTING OFFICE WASHINGTON 1 1930 -~~~ For sale by the Superintendent of Documents, Wanhlngton, D. C. - - - Prico 15 cent. National Oceanic and Atmospheric Administration ERRATA NOTICE One or more conditions of the original document may affect the quality of the image, such as: Discolored pages Faded or light ink Binding intrudes into the text This has been a co-operative project between the NOAA Central Library and the Climate Database Modernization Program, National Climate Data Center (NCDC). To view the original document, please contact the NOAA Central Library in Silver Spring, MD at (301) 713-2607 x124 or [email protected]. LASON Imaging.Contractor 12200 Kiln Court Beltsville, MD 20704- 1387 January 1,2006 Blank page retained for pagination PUBLICATION NOTICES The Coast and Geodetic Survey maintains mailing lists containing the names and addresses of persons interested in its publications. When a new publica- tion or a new edition of a publication is issued on any of the subjects covered by the mailing list, a circular showing the scope and contents of the publication is sent to each person whose name and address is on the mailing list of the subject covered by the publication. If you desire to receive notices regarding publications of the Coast and Geodetic Survey as issued, you should write to the Director of the Coast arid Geodetic Survey, Washington, D. C., indicating the mailing lists on which you .wish your name entered, or, if you prefer! you may check the lists on the form below, remove this sheet from the publication, and mail it to the Director of the Coast and Geodetic Survey, Washington, D. C. (Date) - ___ .- - - __-_-__ ____ - __ - - The DIRECTOR,UNITED STATES COAST AND GEODlCTIC SURVEY, Washington, D. C. DEARSIR: I desire that my name shall be placed on the mailing lists indicated by check below to receive notices regarding publications issued by the United States Coast and Geodetic Survev: 0 109. Astronomic Work. 0 109-A. Base Lines. 109-13. Coast Pilot. 0 109-c. Currents. 0 109-D. Geodesy, or Measurements of the Earth. 0 109-E. Gravitv. 0 109-F. Hydrography. 0 109-G. Leveling. 0 109-H. Nautical Charts. 0 109-1. 109-5. 0 109-K. 0 109-L. 0 109-M. 0 109-N. 0 109-0. 0 109-Y. 0 109-R. Blank page retained for pagination CONTENTS 1 2 3 4 4 4 6 6 6 8 10 17 17 18 19 19 27 28 32 36 36 37 38 39 39 40 41 48 51 56 65 09 8 40 65 66 67 88 TRIANGULATION IN COLORADO (1927 DATUM) By OSCAR 8. ADAMS,Senior Mathematician,. United Slates Coast and Geodetic Survey READJUSTMENT OF TRIANGULATION, WBSTERN UNITED STATES This volume contains the results of the first-order triangulation executed by the United States Coast and Geodetic Siirvey in the State of Colorado. The eographic positions contained herein are on a new datum and superse L9e thpositzons in Colorado which appeared in Special Publicatson No. 19 of this bureau. The triangulation of the United States has been built up by con- tinually adding new Rrcs .to those already measured, and for many years in adjusting this triangulation the plan had to be followed of fitting the new arcs of triangulation to the old ones which had been reviously adjusted. This method was the only one that could have Keen followed up to the time that the western half of the triangulation net of the country had been extended to such a degree that the arcs formed many closed loops-a.condition reached in the year 1926. It then became necessary, m order to secure what may be called standard or final geographlc positions to the westward of the ninety- eighth meridian, to make an adjustment of the net as a whole. This was done by a method devised at the ofice of the Coast and Geodetic Survey,' and the resulting. geographic positions for all of the western triangulation are now available to surveyors and other engineers who may wish to have final geographic positions for their operations. ?'his volume is the first of a series of publications, each of which will give the geographic positions on the new datum for the triangula- tion stations of a State, or occasionally of two States, together with the descriptions of the same stations. COMPUTATIONS The adjustments of the qrcs included in this publication form part of the eneral adjustment in the western part of the United States. The caf culations of the adjustments were made by TI. C. Mitchell, €1. S. Rappleye, G. L. Fentress, H. P. Kaufmann, and others in the division of geodesy of thjs bureau. C. H. Swick and 0. P. Sutherland assisted in the preparation of the manuscript for publication. GENERAL DESCRIPTION OB TABLES AND SKETCHES The tables of geographic position!, on pages 19 to 35, also contain the distances between contiguous triangulation stations m meters and feet, the logarithms of the distances in meters, and the azimuths of the lines joining these stations. The distances are corrected for elevation above mean sea level, and the azimuths are referred to the true south. Anyone who wishes to obtain the actual distances between the triangulation stations should use the formula given on page 17, by which the true distance at the mean elevation of the sta- tions can be derived from tho distance at sea level. The doscriptions 1 For a dfflWipti0n of the method wed Bpeciol Publication No. 16% 1 2 U. S. COAST AND GEODETIC SURVEY of the stations, given on pages 41 to 55, are designed to enabic the engineer to recover and identify the station mark afkr he has visited the general locality of the station. There will be times when the descri tion, so far as witness and other marks are concerned, will have ecome out of date from changes by nature or by the work of man. B Any engineer who may visit a station and find that the descrip- tion does not truly represent the present conditions, or who finds the mark destroyed or mutilated, should report the facts to the Director of the Coast and Geodetic Survey at Washington, D. C., in order that the files of this office may be kept up to date. Thc engineer should realize that the triangulation extended over the country by the Coast and Geodetic Survey is a ublic survey made for the usc of the people. The stations really beP ong to the States in which they are located, and the engineer who is so fortunate as to find one of these stations located near his work should help to perpetuate the monuments in order that they may be of continuous service and value to his locality. The Coast and Geodetic Survey offici& will, from time to time, visit the stations established and wlll re-mark and rede- scribe them if necessar Near the back of tlis publication will be found sketches which show graphically the approximate locations of the stations and thc lines over which observations were madc. It is suggested that if one should wish to learn whether there are triangulation stations in tho vicinity of his work he should first consult the sketches. He can obtain from them the names of the stations that may be of help to him; then he should turn to the index on page 69 of this volume, from which he can find the pages upon which the descriptions and geographic positions of the stations appear. OTHER PUBLICATIONS OF VALUE TO THE ENGINEER If an engineer wishes to compute geographic positions for the strt- tions of any trian ulation that he may execute, he should procure a copy of Coast ancf Geodetic Survey Special Publication No. 8 from the Superintendent of Documents,. Washington, D. C. The cost of this publication is 25 cents. If he is interested in knowing the length in meters of the depees,.niinutes, and seconds of latitude and longi- tude in the region 111 which he is working, he can obtain them from Special Publication No. 5, which can be purchased at a cost of 20 cents from the Superintendent of Documents. There are occasions, especially b-cities, when the engineer wishes to use plane coordinates for hls tnangulation stations rather than spherical coordinates. In such cases he should procurc from l#hc Su erintendent of Documents Special Publication No. 71, entitlcd “gelation between Plane Rectangular Coordinates and Geographlc Positions,” which costs 10 cents. This publication also describes the methods of transforming plane coordinates to spherical ones. The Coast and Geodetic Survey has issued a number of manuals on the various classes of !ts work. The ones that would be of value to an engineer in connection with triangulation, including base measure- ments, are Special Publication No. 120, Manual of First-Order Trian- gulation, cost 40 cents; Special Publication No. 145, Manual of Second and Third Order Triangulation and Trayerse, cost GO cents; and Spe- cial Publication No. 137, Manual of First-Order Traverse, cost 30 Cents. If he is interested in the determination of azimuth to a high !PRIANGULATLON IN COLORADO 3 degree of accuracy, he should procure a copy of Special Publication No. 14, Determination of Time, Longitude, Latitude, and Azimuth, cost 35 cents. If he is interested only in the determination of approx- imate azimuths, hc should secure a copy of Serial No.