64 INSTRUCTIONS FOR MAKING FOREST SURVEYS, ETC. 

 PLATTING THE SURVEY. 



When a plane table is used, the survey and platting 

 progress together, but if other methods are used it is 

 necessary to "plat" the notes. This should be done on 

 the prescribed forms, using one of the standard scales 

 which are described on page 66. Be sure that the plat 

 shows the scale, as well as "what it is, where it is, who 

 made it, and the'date." If the plat does not "close/' 

 throw the error into the sides or angles which are most 

 liable to be inaccurate on account of difficulties in the 

 field work. If local attraction was encountered at one 

 corner the error is likely to be in that angle. If offsets 

 were made, or very rough or steep country traversed on 

 one side, the mistake is probably in the chaining of that 

 side. An error of one link to the chain is allowable. If 

 a larger error appears in platting, the field work must 

 be repeated. 



MAP MAKING IN THE FIELD. 



After the salient points of the topography have been 

 located by plane table, and the roads, streams, or sum- 

 mits have been traversed by compass surveys, it remains 

 for the surveyor to sketch in the contours. Some of 

 this may l><3 done when the peaks are located and when 

 the distances are chained, and the result is -a skeleton 

 map upon which it remains to fill in the balance by the 

 eye. This is a matter of practice. It is an excellent 

 plan to learn to read contour 'maps, such as are pub- 

 lished by the Geological Survey, and the student should 

 provide himself with a topographic sheet of some 

 region with which he is well acquainted and learn to 



