116 A MANUAL FOB NORTHERN WOODSMEN 



2. In securing an efficient map, a main principle to hold 

 in mind is the relation between accurate and expensive 

 work and work of a lower degree of accuracy. If elevations 

 in a topographic survey were put in by level only, and 

 horizontal positions fixed by compass and chain, an 

 accurate result would be had, it is true, but it would be at 

 enormous cost. On the other hand, the use of barometer 

 and pacing alone might furnish a map so inaccurate as to 

 be of little account. The effort must be to construct a 

 skeleton of reliable points and lines, to which less accurate 

 and costly work may be tied to put points within reach, 

 one might say, of the weaker method or instrument. Sur- 

 veyor's compass and chain, staff compass and pacing, and 

 sketching form such a series in the horizontal determination 

 of points. The level, the aneroid, and sketching are similarly 

 related in height work. Sketching is the final term in any 

 case, and much depends on it for both accuracy and 

 appearance. In a way, it is easy, but real excellence in 

 the art depends on a combination of eye, memory, and 

 artistic sense. 



3. Throughout any ordinary work of this kind, it has to 

 be understood that much detail is too fine for representa- 

 tion or is really unessential, and on that account the 

 topographer should neglect it. Makers of accurate maps 

 neglect only what does not show on the scale of the map. 

 Woodsmen will generally find it necessary to adopt a 

 more liberal rule. 



The conditions under which forest mapping is done have 

 an influence on methods in the following ways. 



1. Timber growth itself presents an obstacle to clear 

 sighting. That favors the compass as against the transit 

 for boundary work, and in the same way, in topographic 

 mapping, triangulation and the vertical angle are put at 

 a disadvantage as agaiast methods which can be carried 

 on under the cover of the woods. 



2. Forest topography should generally be tied to 

 property boundaries, rather than to topographic promi- 

 nences. Commonly, a survey of his boundaries is the first 

 and most important work to be done for an owner who 

 wants accurate knowledge about his land. It will, there- 



