Forest Mensuration 41 



b. Caliper the trees in the circle into two-inch classes; estimate the 

 average tree for each class and allow for defects as before. 



In both cases a map must show the site of the sample circles. The 

 circle method is not allowed in scattering timber. At least 5% of the 

 entire area must be sample-circled. 



2. Sample strips. Strips should be four rods wide, should run across 

 ridges, should be shown on a map. Otherwise proceed as under I. 



3. The "forty" method is used on surveyed land. It is an entire-area 

 method applied to 40 acres. The sides of a "forty" are 80 x 80 rods, 

 equal to 440 x 440 yards. Prescriptions : 



a. Traverse each "forty" on lines about 100 yards apart, thus crossing 

 4 times. 



b. Halt at every 100 yards and estimate the trees within a square of 

 loo yards surrounding the stopping place. 



c. If possible, have a compass man control the length and the direc- 

 tion of your runs. 



PARAGRAPH LXIII. 



SAMPLE SQUARES. 



Sample squares containing about one acre are used in Maine and in 

 Northern New York. The side of a sample square is 14 rods. A cruiser, 

 from the center of the square, under the density of the growth existing 

 in Maine and New York, can overlook a circle of 7 poles radius sur- 

 rounding him. Hence, as a matter of fact or rather of theory he skips 

 the corners of the square, counting only the trees in a circle which has 

 the side of the square for its diameter. The square contains 196 square 

 rods, whereas the circle of 7 poles radius contains 155 square rods. The 

 cruiser estimates the contents of all trees within the "square" from his 

 central standpoint. 



PARAGRAPH LXIV. 



PISGAH FOREST METHOD OF 1896. 



1. The diameters of all trees promising to yield a log are measured 

 in diameter classes of l /z foot interval by a crew of 4 to 5 helpers armed 

 with Biltmore sticks. 



The diameters are measured (or often estimated if beyond reach) at 

 the point above which the tree is supposed to be sound. 



2. Each tree measured is marked by a blaze. The foreman enters on 

 a tally sheet the species and the diameters called out by the helpers. A 

 special tally sheet is used for each cove. 



3. The average contents of the diameter classes are estimated with the 

 help of sample trees selected for each species and each diameter a very 

 uncertain estimate owing to the unsoundness of the trees. 



