ANGULAR SURVEYING 51 



TRAVERSING 



In surveying, a traverse is a series of consecutive courses whose 

 lengths and directions are determined by measurement. For 

 determining the directions of the courses of a traverse, three 

 methods are commonly employed, namely, by bearings, in 

 which method the directions of the courses of the traverse are 

 determined by their magnetic bearings; by azimuths, in which 

 method the directions of the courses of the traverse are deter- 

 mined by their azimuths; and by deflection angles, or by deflec- 

 tions, in which method the relative directions of the courses of 

 the traverse are determined by measuring the angle by which 

 the direction of each course is deflected from the prolongation 

 of the immediately preceding course. 



Traversing by Azimuth. The azimuth of a line is the angle 

 that the line makes with the meridian. It is measured frorr 

 to 360, either from the south in the direction west north 

 east, or from the north in the direction east south west. 

 Sometimes, a line that is neither a true nor a magnetic meridian 

 is used as a line of reference from which azimuths are measured 

 in the same manner as if the line were a meridian. Such a line 

 of reference is called an assumed meridian, or simply a meridian. 



When the directions of courses are given by their azimuths, 

 a transit is used with its horizontal circle graduated from 

 to 360. It often happens that, by the addition of certain 

 angles, an azimuth greater than 360 is obtained. An azimuth 

 greater than 360 is equal to the same azimuth diminished by 

 360. 



Process of Azimuth Traversing. Referring to the illustra- 

 tion on page 52, suppose that A is a given point on a line AF 

 previously surveyed, and that it is desired to connect this point 

 with the point by a traverse following the contour of the 

 surface in such a manner as to give about the minimum rise 

 and fall. The true bearing of AF, as previously determined, 

 is N 42 36' W; therefore, its azimuth, counted from the north, 

 is 360 -42 36' = 317 24'. The points B, C, and D are 

 chosen in advance of the survey in such positions as will 

 fulfil the required conditions as nearly as can be judged, 

 each point being selected while the instrument is being moved 



