22 SURVEYS. 



to the office of the Chief Engineer, distinctly marked with the 

 name of the line, streams, and all other information neces- 

 sary to identify the locality. 



Tracings of located lines showing government and prop- 

 erty lines, streams and date of commencing and completing 

 Burvey, must be made and sent promptly to the office of Chief 

 Engineer, as soon as each section of 20 miles has been finally 

 located, for the purpose of filing map of definite location in 

 the land office. 



All changes of line made after the map of definite location 

 has been filed in the general land office must be approved by 

 the engineer in charge before being adopted, and as soon as 

 made, reported to the Chief Engineer with a tracing of new 

 and old line, and tracing profile of the part altered. 



Topography on general maps should be given for a distance 

 of 1,500 ft. on each side of the center line," and further when 

 necessary to show important features. In order to facilitate 

 plotting contour topography, the notes should give distances 

 of contours from the center line. 



All courses of line must be given in reference to the true 

 meridian, and for that purpose an observation must be taken 

 upon starting the survey and the true course recorded in the 

 field books, as the work progresses. An additional observa- 

 tion should be taken for the correction of meridianal con- 

 vergency whenever the extent of the survey shall attain a de- 

 parture of one-half degree of longitude. 



Curves and bearings of tangents shall be noted on the maps 

 and profiles in the manner shown on the samples furnished. 

 .When practicable give true bearings instead of magnetic. 

 State which is given. 



To avoid cumulative errors, when platting lines, all angles 

 must be laid off from some standard bearing, using the cal- 

 culated course for this purpose. This can be done best by lay- 

 ing off any convenient bearing in the general direction of the 

 survey and transferring all angles turned from this line by 

 parallel rules or triangles, to the last point scaled. This will, 

 on located lines, require all tangents to be calculated from in- 

 tersection to intersection. 

 Indicate on the map, or otherwise, the width and extent of 



