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 bysome of the company, .that m these trials consideration might be had ofthe age, knottinefs, solidity, several soils, and parts of trees, &c. and SirRobert Murray did particularly add, that it might be observed how farany 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 ouncesweight, broken with eight hundred pounds weight, .and very little bend-ing with seven hundred and fifty j by which the hypothesis seems to beconfirmed, that in similar pieces the proportion of the breaking-weight isaccording to the basis of the wood broken.. Secondly, of a piece of Firtwo feet long, one inch square, , cut away from the middle both ways tohalf 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 samethicknefs every way was formerly broken with: the difference was guefsedto proceed from the more firmnefs of this other piece.
His Lordship, the Prefident, was desired to contribute to the prosecu-*tion of this experiment, and particularly to consider what line a beam mustbe cut in, and how thick it ought to be at the extreme, to be equallystrong; 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 takentwo pieces of Fir, each two feet long, and one inch square, which werebroken, the one long-ways with three hundred pounds weight, the othertransverse-ways with two hundred and fifty pounds: Secondly, two piecesof the same wood, of each three-quarters of an inch square, and two feetJong, broken, the one long-ways with one hundred and tw 7 enty-five ; theother transverse with one hundred pounds weight: Thirdly, one piece oftwo feet long and half an inch square, broken long-ways with eighty-onepounds: Fourthly, one piece cut out of a crooked Oaken billet, .with an.arching grain, about three quarters of an inch square, and two feet long,broken with feventy-five pounds.