112 THE BOOK OF FORESTRY 



tally man generally has charge of the party and from 

 his position can oversee the work of the other men. 



These strips should always be run up and down hill 

 for the reason that a better average of the timber may 

 be obtained in this way. The tallest forest trees and 

 best stands of timber are always found in the valley 

 bottoms where the soil is deep and the wash from the 

 hillsides provides plenty of moisture. Upon the 

 mountaintops where the soil is thin and dry the trees 

 are short, scrubby and far apart; hence to get a fair 

 average of the timber in a valley a strip from one 

 mountaintop down the slope to the bottom and up the 

 other side must be run. 



The distance that may be covered in a day depends 

 largely on how close the trees stand and how hilly the 

 country is. In dense forest like the spruce forests of 

 Maine two and one-half miles or twenty acres actually 

 measured, is a good day's work. If it has been decided 

 to caliper one acre in ten, two hundred acres have been 

 accounted for. In gently rolling country where the 

 trees are far apart from five to six miles of line may 

 be run in a day. 



Sample Plot Method. In some cases it may be more 

 convenient to measure sample acres than an average 

 strip. Then the contents of the entire forest is computed 

 in practically the same way by laying off a number of 

 one-half or one-quarter acre plots and getting the diam- 

 eters of all the trees upon it. If one-twentieth of the 

 forest is included in these sample plots, the sum of their 

 volumes multiplied by twenty will give the total stand 

 of timber. However, the total area of the forest property 

 must be known. 



Forestry students often obtain summer jobs in val- 

 uation survey parties, because this mechanical method 



