^ur(jcniit0 in Him'plorctr Countries. 

 Clje loljorc SiirkjT. 



(^Abridged Paper. ^ 



By a. WHARTON METCALFE, Assoc. M. Inst. C.E. 



SURVEYS undertaken in civilized countries differ in the 

 methods by which they are carried out from those exe- 

 cuted in lands uncivilized and unexplored. In the former 

 case there are many and different methods of attaining the 

 desired end ; the choice of any one method depends chietly 

 upon the degree of accuracy required, and upon such con- 

 siderations as rapidity of execution, economy, and conveni- 

 ence. In the latter case circumstances often make it 

 desirable to resort to simple methods ; as triangulation, etc. 

 are impracticable in an unknown country thickly covered 

 with jungle: the method of traversing is therefore usually 

 adopted. 



Traversing upon land may be defined as the art of deter- 

 mining the length and direction of the sides of a rectilinear 

 polygon, following the line of the proposed works or routes of 

 commanication ; the polygon may be closed or unclosed, but 

 in a new country it would usually be the latter. The methods 

 adopted for engineering and land surveys in open country are 

 various ; thus we have the chain survey, theodolite surveys, 

 compass surveys, planetable surveys, as well as theodolite 

 and compass traverses. In the Abyssinian Campaign trian- 



165 



