ABSTRACTS 



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GEODESY. — Triangulation in Alabama and Mississippi. Walter F. 

 Reynolds, U. S. Coast and Geodetic Survey Special Publication 

 No. 24. Pp. 71. 1915. 



This publication contains the positions and descriptions of nearly 

 600 triangulation stations in Alabama and on the Gulf coast of Missis- 

 sippi. The primary stations included in the volume are a part of the 

 Eastern Oblique Arc, the field work of which was completed in 1898. 

 The results of that triangulation appeared in Special Publication No. 

 7 in 1901, the positions being on the same datum as that used for the 

 Transcontinental Triangulation, the results of which appeared in Spe- 

 cial Publication No. 4. Since that time the United States Standard 

 Datum, now called the North American Datum, was adopted and it 

 became necessary to change the old positions to that datum. 



The field work of the triangulation was done between the years 1848 

 and 1911. Many of the stations of the early surveys are lost, but from 

 time to time tertiary triangulation has been done along the coast to 

 supplement the triangulation of the Oblique Arc. 



The elevations of the triangulation stations in Alabama appeared in 

 Special Publication No. 7, but the elevations of several of the stations 

 have since been determined by precise leveling and are now held fixed 

 in a rigid adjustment since made of all the elevations. In this adjust- 

 ment are also included the elevations of a number of stations in Georgia 

 and Tennessee. On account of the new adjustment of the net, the 

 elevations appearing in this publication will differ slightly from those 

 in Special Publication No. 7. 



As a full discussion of the errors and the accuracy of the triangulation 

 of the Eastern Oblique Arc appeared in Special Publication No. 7, it 

 was not considered necessary to give any discussion of these subjects 

 in the new work. There is a table comparing the accuracy of the tri- 

 angulation in this volume with that of the entire Oblique Arc. 



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