434 Forestry Quarterly 



Accurate Map Essential 



The logging engineer's first demand in taking over a new job is 

 for an accurate topographic map not only of the area that his 

 company intends to log, but of all the adjacent territory. There 

 is no need to dwell on the necessity for an accurate contour map. 

 It becomes the working plan of the logging engineer on which he 

 makes the locations for railroads, spurs, flumes, chutes, roads, 

 camps and cable systems. 



The cruiser's maps, giving locations of streams and ridges, 

 with occasional elevations taken with the aneroid barometer, 

 served their purpose in their day, but modern logging business 

 requires more detail. The topography must be accurately 

 mapped, the reports must give a careful classification of all timber, 

 for each species as standing, dead and down, timber suitable for 

 piling, poles and ties, with an estimate of probable defects; also 

 soil classification reports, conditions of undergrowth and mineral 

 indications. 



The surveys for topogi'aphic maps for logging operations are 

 made in various ways. The method to be used is determined by 

 the lay of the land and the density of the forest growth. Until a 

 year or two ago the custom was to make all such surveys by the 

 aneroid method, which is simply a refinement of the methods used 

 by timber cruisers. Elevations were determined by primary 

 leveling along certain lines selected as base lines. If the area has 

 been previously covered by the survey of the United States 

 General Land Office, it is customary to establish the base along 

 section lines ; while in unsurveyed territory irregular traverses are 

 run along roads, trails or ridges, the work usually being done by 

 transit and stadia and the elevation computed at fixed intervals. 

 From these base lines parallel "strips" are run. 



The strip crew usually consists of a compassman and an esti- 

 mator. The compassman runs a rough line by a box compass 

 and paces the distances. Also he carries an aneroid barometer 

 which he sets with a stationary camp barograph in the morning 

 and sketches the contours each side of the line on his map. It 

 is also necessary to record the time at which the aneroid readings 

 were taken in order to make the corrections for the fluctuations 

 of the instrttment during the day. 



The aneroid, while a handy instrument for taking rough eleva- 

 tions, is too eccentric to be relied on to do accurate work, as any 



