74 THE WOODSMAN'S HANDBOOK. 



acres largely compensate each other. It is only when the chain- 

 ing is used for a topographic map as well as an estimate that accu- 

 rate chaining on the horizontal is necessary. 



It often happens when a line of strip surveys is run across a given 

 area that the last strip is less than 10 chains in length. Strictly, 

 this should be regarded as a fraction of an acre. Thus, for example, 

 if the last strip is 4J chains in length, it comprises 0.45 of an acre. 

 When the results of the measurements on this short strip are used, 

 and it is necessary to give figures of stand per acre, they must be 

 divided by 0.45. In practice, however, where the forest is uni- 

 form, the whole acre is completed, either by continuing over the 

 line or by turning and finishing inside the line in another direc- 

 tion, in order to facilitate computation and to avoid .fractional 

 acres whose results must be converted into terms of whole acres. 



PREPARATION OF A FOREST MAP. 



The preparation of a forest map often is combined with the esti- 

 mate. In most cases a contour map is not planned, but rather a 

 map which will show simply the distribution of the timber, the 

 forest types, the location of the roads, streams, and main ridges. 

 Such a map is prepared in the following way: When a strip inter- 

 sects a road or stream the tallyman notes the point of intersection 

 and also the direction of the road or stream, so that it can after- 

 wards be located on the map. If a road or stream crosses several 

 strips the points of intersection are connected on the map and the 

 exact location thus indicated. When a stream or road is crossed, 

 the tallyman takes any steps necessary to record its character and 

 width. The description of each acre includes the general direc- 

 tion of the slope, and if there is a marked change in the degree of 

 slope in the middle of the acre, that fact and the point of the 

 change are noted . The location of ridges may thus be determined 

 and sketched on a map from the description of each acre. 



It is possible, also, to make a map of the forest types, because 

 the description of each acre includes a statement of the type. If 

 an acre crosses from one type into another, this fact is explained 

 on the tally sheet and the point of change is indicated, so that the 

 outlines of the different types may be sketched on the map in the 

 same way as the roads and streams. 



