46 FOREST EESEEVE MANUAL. 



of cloth. "Whether full chains (66 feet) or half chains (33 feet) 

 should be used depends largely upon the character of the 

 region. 



In emergency cases, when receipt of an application makes 

 it necessary to lay out a block at once, two men may do the 

 work, running and blazing the boundaries first and measur- 

 ing them later. 



As a rule, the method of surveying each block will be as 

 follows: 



Select a beginning point which can be accurately located, 

 preferably the corner of some previously surveyed block, or, 

 if such is wanting, a point on some stream, road, trail, or 

 cutting which can be definitely described or located on already 

 existing maps. Forks of roads or streams, or intersections 

 of such, afford simple means of location. If no such features 

 exist within or on the boundary of the block, the distance and 

 direction of one given corner of the block from some known 

 point outside should be established. The object of this care 

 in location is not only to facilitate finding the block in the 

 woods, but to allow accurate mapping. The beginning point 

 will usually form one corner of the block, and should be dis- 

 tinctly marked by post and witness tree. 



From this point run, chain, and blaze around the tract, not- 

 ing the length and direction of the line between each corner 

 and the distance to the crossing of all roads, streams, cliffs, 

 and similar features; also the positions of buildings, clearings, 

 or other objects which should appear on the map. Whei'e the 

 boundary of the block follows irregular lines, such as roads, 

 streams, or ridges, the line must never curve, but may be 

 meandered by as many angles and offsets as necssary to follow 

 the general direction. Boundaries formed by roads, streams, 

 open ground, or other unmistakable objects need not be blazed, 

 but in such cases the corners must be clearh' marked. (See 

 sample map, fig. 2.) 



All blazing must be reenforced by the United States mark. 

 Block corners will be marked by posts, monuments, and wit- 

 ness trees, as in the case of districts, except that the marking 

 must show the number of both block and district, as D-1, B-3. 



Since, in many instances, it will be impossible to subdivide 

 an entire district atone time, and the laying out of blocks will 

 follow the receipt of applications, there will be considerable 



