220 LAND VALUATION 



down the expense because a network of triangulation can be built 

 up which will locate the main features better than many miles 

 of compass traverse. With this primary control as a basis the 

 details can be readily filled in with the compass. 



To illustrate the methods used in the determination of the area 

 of timbered tracts take the case of a loo acre lot as the first 

 example. The simplest way to handle this would be to run a 

 base fine with a staff compass and chain along one side or on a 

 convenient road or trail crossing it. Then the estimate strips 

 could be run at regular intervals from this base line and at right 

 angles to the principal streams. By recording the ridge tops and 

 stream crossings on the estimate strips a very complete map may 

 be made at very Httle expense in addition to the cost of the esti- 

 mate itself. A larger tract of say 20,000 acres would be handled 

 in exactly the same way except that greater pains should be taken 

 to make sure that the framework, or primary control, was well 

 fastened together. For this a compass would not be accurate 

 enough. The best instrument would be a planetable with tele- 

 scope alidade so that either triangulation or traverses and stadia 

 measurement could be employed. 



The relative accuracy and cost of the various methods of area 

 determination may be summed up as follows: 



Transit and tape 



Transit and stadia 



Planetable and stadia 



Traverse board and chain. 

 Staff compass and chain. . . 

 Staff compass and pacing. . 

 Traverse board and pacing 

 Hand compass and pacing , 



While this list aims at completeness in enumerating the methods 

 employed in woodland area determination this is not the place 

 to describe each in detail. Surveying manuals like that of Breed 

 and Hosmer should be consulted for such information. It is 

 sufficient for the immediate purpose to give some notion of their 



