/ 



OF FOREST-TREES. 241 



The experiment was ordered to be repeated, and recommended by the CHAP. 

 president to Sir William Petty and Dr. Hook ; and it was suggested by ^--''^ 

 some of the company, that in these trials, consideration might be had of 

 the age, knottiness, solidity, several soils, and parts of trees, &;c. and Sir 

 Robert Murray did particularly add, that it might be observed how far 

 any kind of wood bends before it breaks. 



March 1664. 



The operator gave an account of more pieces of wood broken by weight, 

 viz. a piece of Fir four feet long, two inches thick, and fifty-three ounces 

 weight, broken with eight hundred pounds weight, and very little bend- 

 ing, with seven hundred and fifty ; by which the hypothesis seems to be 

 confirmed, that in similar pieces, the proportion of the breaking- weight is 

 according to the basis of the wood broken. Secondly, of a piece of Fir 

 two feet long, one inch square, cut away from the middle both ways to 

 half an inch, which supported two hundred and fifty pounds weight be- 

 fore it broke, which is more by fifty pounds than a piece of the same 

 thickness every way was formerly broken with : the difference was 

 guessed to proceed from the more firmness of this other piece. 



His lordship, the president, was desired to contribute to the prosecu- 

 tion of this experiment, and particularly to consider what line a beam 

 must be cut in, and how thick it ought to be at the extreme, to be 

 equally strong; which was brought in April 13, but I find it not 

 entered. 



April 20, 1664. 



The experiment of breaking wood was prosecuted, and there were 

 taken two pieces of Fir, each two feet long, and one inch square, which 

 were broken, the one long-ways with three hundred pounds weight, the 

 other transverse-ways with two hundred and fifty pounds : secondly, 

 two pieces of the same wood, each of three quarters of an inch square, 

 and two feet long, broken, the one long-ways with one hundred and 

 twenty-five ; the other transverse with one hundred pounds weight : 

 thirdly, one piece of two feet long and half an inch square, broken long- 

 ways with eighty-one pounds : fourthly, one piece cut out of a crooked 



