I'I4 FOREST COMMISSIONERS REPORT. 



lowing method will give an approximate estimate without the 

 use of instruments and does not require much previous experi- 

 ence. However, the estimate will be more accurate if survey- 

 ing and measuring instruments are used, and if the estimator 

 has had some experience in sizing up timber. 



The method requires a knowledge of the number of acres in 

 the woodlot. The more accurately this is known the better will 

 be the estimate. It may be found roughly by pacing. 



A chain is four rods long, or 66 feet. 



There are ten square chains in an acre. 



There are 160 square rods or 43,560 square feet in an acre. 



A square acre is 208.7 Iee ^ on a side. 



A quarter acre is 104.3 ^ ee t on a side. 



A quarter acre circle has a radius of 59 feet. 



Knowing the total number of acres in the woodlot it is neces- 

 sary to find the average amount of timber standing per acre. 

 To find this average run per acre cruise through the woodlot 

 and select a number of quarter acre plots that appear to average 

 up well with the rest of the stand. This plan will be satisfac- 

 tory where the timber runs uniform. The area of these plots 

 may be estimated by the eye, and checked by pacing or by the 

 tape. A person can estimate a distance of 59 feet from where 

 he stands, in all directions. Count all the trees within this dis- 

 tance. Select a tree that looks to be of average diameter and 

 height. Measure the diameter of this tree at breast height using 

 pocket rule or home made calipers. 



To obtain the board foot contents of this tree, estimate the 

 diameter half way up the merchantable length and using the 

 breast height measurement to go by, allow about two inches of 

 taper for each sixteen feet in height. Multiply this diameter by 

 itself, subtract 60 and multiply the difference by 0.8. The 

 answer will give the num'ber of board feet in the average log, 

 so it must finally be multiplied by the number of 16 foot logs 

 in the tree. 



Example : A tree calipers, breast high, 20 inches. Looking 

 up the stem it is seen that the tree will cut three 16-foot logs. 

 The diameter halfway up, 24 feet, is estimated at 14 inches. 

 14 x 14 — 60 equals 136. Multiply 136 by 0.8 gives 108.8 board 

 feet — the size of the average log. Multiply this by 3, the 

 number of logs in the tree, and we have the number of board 



