198 FOKESTRY WORK 



then moved along the luie, and the point K found in the 

 same manner. 



There remains the curved part of the area to be mea- 

 sured. 



The line AD is poled off, measured, found to be 370 

 yards, and used as a base line. 



Perpendiculars or offsets must be set up at intervals 

 along this line — say every 60 yards, starting from A. 



This makes five offsets, leaving 70 yards between the 

 points L and D. (To erect a perpendicular from a given 

 point, set up the cross-staff so that on looking through 

 one of the saw-cuts the ends of the line can be seen. Then 

 the other saw- cut will point out the direction of the per- 

 pendicular or offset.) 



These offsets are measured and noted. PI 50 yards, 

 OH 60 yards, NG 70 yards, MF 60 yards, LE 50 

 yards. 



The booking may be done in different ways, but the 

 best way, in my opinion, is to draw a rough plan of the 

 area, and marking upon it the points and distances as 

 they are measured. 



The area of the ground may then be worked out in 

 sections from these figures. 



The area of a triangle is found by multiplying the base 

 by the perpendicular height and dividing by 2. 



The area of a trapezoid {a figure with two sides parallel) 

 =mean length of parallel sides multiplied by the per* 

 pendicular distance between them. 



The figures may be set out thus: 



