24 INSTRUCTIONS FOR MAKING FOREST SURVEYS, ETC. 



scale on the map. Proceed as before, and the result will 

 be a map which will truly represent the lines on the 

 ground. (See fig. 5.) 



In this case the points C and D were not visible from 

 A, but if ; instead of being a block of forest, the area were 

 an open meadow, then a second method would be used. 



FIG. 5. Plane-table method in which the table is set up at all the stations. 



Set up at A. Draw lines to B, C, D, and E. Meas- 

 ure AB. Set up at B. Orient on A. Draw lines to 

 C, D, and E. The intersections of the line will give 

 the other three points. The line AB is a base line. 

 (See fig. 6.) 



The third method is an extension of the second and 

 involves some near-by points which can not be located 



