THE THEORY AND PRACTICE OF WORKING PLANS 23 



3. Condition of timber (soundness). 



4. Approximate age of timber. 



For purposes of combining the survey with the timber esti- 

 mate, the strip method of estimating is undoubtedly the best. 

 From a definite base Hne — such as a section boundary or, if in 

 unsurveyed or very rough country, a base Hne previously run 

 out— the strips are run out at right angles, at definite inter- 

 vals. 



Base Lines. — The section Hne serves as an excellent base, 

 especially in fairly level country. Rough topography or the 

 lack of suitable survey Hues as a base make it necessary to es- 

 tabHsh base lines in advance of the actual estimating. They 

 should be located in valley bottoms, along roads, or elsewhere 

 so that they can be easily retraced ; at the same time they give 

 a preliminary topographic control. The distances must of 

 course be measured accurately either by chain or tape or by 

 stadia. The use of stadia — involving a mountain transit or 

 a telescopic alidade — is advisable only in fairly open country 

 or for the primary base lines. The chain or tape is much 

 handier in timbered country; pacing is not accurate enough for 

 this purpose. 



Beginning at some known point, or at least tied thereto by 

 definite triangulation, the base Hne system is developed over the 

 whole forest Hke the stem and branches of a tree. The number 

 of base lines must depend on the intensity of the work; better 

 fewer and accurate than many and sHpshod. 



A traverse board and open-sight aHdade are exceUent for 

 base-Hne work unless the timber is too dense; then chaining alone 

 is possible, and the notes must be plotted not only upon return 

 to camp, but immediately, in the rough, so as to determine 

 where the equidistant strip stations are to be established. 

 For the base line traverse will necessarily be a zigzag and the 

 strip stations must be exactly equidistant. They are usually 

 marked with a stake and a pile of stones or a blaze, scribed or 

 blue-penciled with the number and the elevation of the station. 

 For purposes of identification it is well to place the station close 



