214 On the Mensuration ofTimfier. ■» 



timber, as fig. 1, (Plate V.) to be in length, AB or CE, 2# 

 feet; in brcadlh, AC or B E, 24 inches f and in depth, AD 

 or EF, 12 inches; then the breadth 24 multiplied by the 

 depth 12, gives 2S8 superficial inches (144 of which make 

 a superficial or plane foot) for the area or measure of the 

 end, which being divided* by 144 gives two superficial feet, 

 which, multiplied by the length 25, gives 50 cubic feet, or. 

 one load, for the measure or content. Planks and boards 

 are also reduced to this measure by taking their length, 

 breadth, and thickness. 



The second, or foot round measure, occurs in the com- 

 mon method used in measuring round timber, or whole trees, 

 either while standing or after being felled. If the tree tapera 

 regularly from the bottom or but, to the top or smaller end, 

 as in fig. 2, it is measured by taking the length AB, and 

 thereby finding the middle C, and then by a string taking 

 the circumference or girt at C and applying the same to a 

 carpenter's rule to take the inches f, one quarter of which is 

 called the quarter girt, or more commonly the girt ; then 

 the girt is multiplied by itself, divided by 144 to reduce it 

 to feet, and these multiplied by the length, to obtain the 

 content. For example: suppose a tree to be in length AB 

 25 feet, and that its circumference in the middle at C is 

 68 inches ; then the fourth of this, or 1/ inches, is the girt, 

 and the girt 17 inches multiplied by T7 is 2$Q inches, and 

 this divided by 144 is two feet, (neglecting the small frac- 

 tion 1- 144th of a foot,) which multiplied by 25- feet, the 

 length, gives the measure or content 50 feet round measure,, 

 or one load. Now since the girt in the middle at C re- 

 maining the same, the circumferences at the two ends- may 

 and do in practice vary, in all proportions, from that of 

 being only 6 inches girt or 24 inches circumference at the 

 smallest end B,.fig. 3; the but A at the same time being v 

 very large, and the tree then differing but little from the 

 cone AD, to the case in which the two ends A and B are 



* In this and the following examples, I have reduced the area into feet 

 (by dividing by 144) previous to multiplying by the length, as better 

 calculated for showing the reason of the operation; but in practice it is 

 more usual and ready to multiply by the length previous to dividing by 

 144. 



f A string is constantly used by the buyers of timber : but the gra- 

 duated tapes invented for the purpose, and made by Cary, optician, in 

 the Strand, are more exa«:, and much more expeditious and e;i: 4 y in prac- 

 tice; and hire I would remark, that the allowance of the girt for the 

 bark ought to be 6^ times the thickness of the bark, and not any certain 

 proportion of the girt, much less a fixed number of inches, as some buyers 

 will contend. 



equal, 



