648 



USEFUL REFERENCES 



The sight line is then extended to the ground by means of a string. From the 

 point where this touches the ground (C in the figure) to the centre of the trunk 

 will represent the actual height of the tree; that is, the horizontal line A C is 

 equal to the vertical A B. If the tree were blown or cut down its top would 

 follow the course showed by the curve line and rest at C. 



Another method. Make two lines on the ground exactly three feet 

 apart. On one of the lines drive a stake in the ground so that the top of the 

 stake will be exactly three feet from the ground; when the shadow of the stake 

 will have reached the other line, the shadow cast by the tree will be precisely 

 the length of the height of the tree, and by measuring the length of the shadow 

 at that moment you will obtain the exact height of the tree. The measurements 

 should be taken on level ground. If the tree is leaning, incline the stake at as 

 nearly the same angle as possible at which the tree inclines. 





A C 



MEASURING THE HEIGHT OF TREES 



110 yds. long and 44 yds. wide 

 88' 55 

 69i 70 



Measuring land. The following lengths multiplied by the correspond- 

 ing breadths equal an acre : 



988 yds. long and 5 yds. wide. 

 484 10 

 220 , 22 

 121 40 



A yard is a good long stride, and few men step a yard in their natural 

 stride. 



To measure Timber. Take the girth in inches in the middle, divide it 

 by 4, and square the result, which gives the mean sectional area of the trunk ; 

 multiply the product by the length of the tree in feet, divide by 144 and the 

 quotient is the contents in cubic feet. Where there is bark, an allowance must 

 be made for this. The usual allowance varying from inch to li inch to every 

 foot of quarter girth ; thus, the total quarter girth being 24 inches, and the bark 

 being thick, a deduction of 5 inches or 3 inches would be necessary, the quarter 



