32 A MANUAL FOR NORTHERN WOODSMEN 



cuit of a farm's boundaries by compass and chain is a 

 traverse. So is the survey of a road by usual methods. 



When a survey has been made in this fashion the notes 

 are for some purposes best worked up after a method 

 called " computing by traverse," the principles and appli- 

 cations of which are developed in the following paragraphs. 



If a course is run out N 30 E 20 chains, a certain dis- 

 tance is made in a northerly direction, also a certain dis- 

 tance in a direction east. The distance made in the former 

 direction is called latitude ; in the latter, departure. In this 

 case it is north latitude and easterly departure. These 

 elements may be made evident on a plot by drawing a 

 meridian and base line through the starting point and 

 lines perpendicular to these from the point reached. These 

 distances are also to be obtained from traverse tables. 



The same is true of a course run in any direction and 

 for any distance. Any course not run exactly east and west 

 makes northing or southing. The former is reckoned as 

 positive latitude, with the sign (+). The latter is negative 

 or ( ) latitude. Similarly, distance made in an easterly 

 direction is (+) departure; that made towards the west 

 ( ) departure. If several courses are run in succession, 

 the sum, algebraically reckoned, of their latitudes and 

 their departures gives the position of the point finally 

 attained. 



This method of reckoning, using traverse tables for the 

 purpose, has a wide use in connection with land surveying. 

 The traverse table given on pages 214-219 furnishes the 

 elements for 15' courses, those usually employed in com- 

 pass work. The following is a simple problem illustrating 

 their use. 



In running a section line due north, the surveyor conies 

 to a lake shore. Setting there a post, duly marked, he runs 

 round the lake near the shore by the following courses : 



N 50 E 12 chains. 



N 9 30' E 20 



N 40 W 9 



S 80 W 6.81 " 



Reckoning up his courses by the traverse table, he finds 



