24 THE THEORY AND PRACTICE OF WORKING PLANS 



to some road, trail, stream, or other topographic feature. The 

 elevation is determined by aneroid barometer readings carried 

 from some point of known elevation. Where transit or telescopic 

 alidade or a clinometer is used it can also be determined by the 

 vertical angles. The crossings of all roads and trails, of creeks, 

 etc., are noted, either directly plotted on the traverse board 

 or else entered in the note-book; the elevation at these crossings 

 is also noted. 



If the forest is so large that the estimating will require several 

 seasons, only so much of the base-line work need be completed 

 in advance as will be used in that season. However, base-line 

 work can often be done to advantage several months before the 

 detailed estimates are begun. 



Wherever possible, the forest organizer should himself be 

 in charge of the base-line work. Three men constitute the 

 ordinary base-line crew; two will suffice at a pinch, though it is 

 better to have two to chain and one for the traverse board or 

 to enter notes, take aneroid readings, etc. 



The Strips. — The estimate strips should always run across 

 the topography; only in that way will average conditions be 

 secured. The size of the crew depends on the method of esti- 

 mating employed. The ordinary strip survey crew consists 

 of two caliper men, and a head and a rear chainman. The 

 former runs the compass, the last named takes notes on topog- 

 raphy and elevation and enters the diameters breast high as 

 called out by the cahper men. Each strip is usually one chain 

 wide. 



W^here the strip is not chained, the crew can be reduced to 

 three, or even two, the compassman to pace and keep notes, 

 two (or one) to caliper. 



Where trained men are used, calipering is seldom necessary; 

 here two men — one to pace and keep notes, one to estimate 

 diameters — suffice . 



In open timber the strips can be widened to one chain on 

 each side of the hne. 



One man can run a strip, but he can scarcely manage com- 



i 



