£16 On the Mensuration ofTimter. 



the calliper of the tree : this calliper is multiplied by itself, 

 divided by 144 to reduce it to feet, and these multiplied by 

 the length to get the content or measure of the tree. For 

 example: suppose a hewn tree to be in length AB 25 feet, 

 and at the middle C to calliper in depth i/£ inches, and in 

 breadth 16^- inches, then is 17 inches the calliper: this 

 multiplied by 1/ gives 28 J>, and this divided by 144 giy€$ 

 two feet (neglecting a small fraction), which multiplied by 

 the length 25 feet, gives 50 feet square measure, or one 

 Joad. On account of the tapering or unequal dimensions 

 of the two ends, also on account of the unequal manner in 

 which timber is hewn, some trees having onlv just a chip 

 taken off their sides, and others being hewn till nearlv die- 

 square, and in all the intermediate degrees ; and further, 

 on account of the loss of the corners, the real quantity of 

 the foot square measure is still more uncertain and vague 

 than the foot round measure, for it varies from about 1360 

 to about 2000 cubic inches, being sometimes below and 

 sometimes above the truth : but it should be remarked, that 

 the cubic inches mentioned above, as the limits within 

 which the foot round measure and the foot square measure 

 vary, is only on a supposition that the sides of the tree are; 

 regular, or that it has no particular swelling in the middle 

 or girting place to cause it to girt or calliper more, or hol- 

 low to cause it to girt or calliper less, than it would if the 

 tree were regular; for in these cases (which too frequently 

 occur in practice) the round measure and square measure; 

 are often still more wide of the truth. 



If a sided or hewn tree does not taper regularlv through- 

 out, or has the knots or stops described above in the case of 

 round timber, then the tree is measured in different lengths, 

 and the contents of the parts are added together for the con- 

 tent of the whole tree, as in the case of round timber. In 

 like manner, the branches reserved and sold for knees or 

 braces in ships, barges, &c. either round or hewn, are mea- 

 sured in two lengths. , 



The first of the above, or cubic measure, will prove con- 

 sistent with the weight; thus, if 10 cubic feet of a tree 

 weigh 578 lb., 30 cubic feet of the same tree will weigh 

 1/34 lb. ; but in either of the other measures it is but in 

 some very rare cases that 30 feet of a tfee will be found to 

 weigh three times as much as 10 feet of the same tree even 

 when measured by the same mode ! The difference in the 

 Weights of the round mease.re and the square measure is so 

 considerable, that for the purposes of f. eight or carriage it 

 is an established custom that 40 feet of round timber make 



a load, 



