Timber Sales in Selection Forests 91 



of known diameter is often useful later in applying volume 

 tables. 



The other equipment will consist of a compass, the Stand- 

 ard Forest Service Compass being admirably adapted to the 

 purpose, and calipers. The "Biltmore Stick" will serve for cali- 

 pers and is far more conveniently carried, but these have not 

 been generally supplied to Forest officers. Distance measure- 

 ments are made by pacing. 



Parallel Courses. The area should be covered systematic- 

 ally along parallel lines, pacing the distances and using the com- 

 pass for getting the courses. The distance between the lines 

 should be uniform, not so much for the map making as for the 

 stock data. Because of the scale, chosen in reference to the 

 ruled map sheet, the distance between the parallel lines should 

 be some multiple of 330 feet. If quarter acre plots, on which 

 stock data is obtained, are used, the distance between these lines 

 is usually 660 feet. With larger sample plots 990 feet would 

 be satisfactory, or in very careful work small plots only 330 

 feet apart. The lines should be so close that no essential features 

 of the map or stock may be missed. The courses should be 

 toward the cardinal points in order that no protractor or scale 

 may be needed. 



Stations at regular Intervals. At regular intervals, usually 

 of 330 feet, and less frequently of 660 feet, stops, or stations, 

 are made on the lines. At these stations, consecutively num- 

 bered, the map features are sketched in and interpolations made. 



Gathering Stock Data. 



While the map is thus being made, at each or alternate 

 stations a sample plot is laid off and a record is made of the 

 stock thereon. Should the station and sample plot, however, 

 fall within an area that is not merchantable forest, no stock is 

 recorded for it, but the map work is continued as usual. In this 

 case, of course, there is no sample plot data to enter into the 

 average stock data. If the sale area contains such small patches 

 of non-commercial forest or parks that they cannot be well map- 

 ped, a sample plot had best be assigned to such stations. But 

 i note should be attached that it contains no stock, in order that 

 the average stock shall include these areas as if they did con- 

 tain stock, since the map will not indicate that there are these 

 small patches of non merchantable timber or blanks. 



The sample plots are numbered to correspond with the 



