322 On the Durability‘of Buildings,&c.[May

from what would cauſe its decay, and the timber increaſed in quantity is conſiderably more than the extra labour and expence,

For example, a trée of oak, forty feet in length, two feet at the butt and_ one foot at the tóp, when chopped, ſawn, and put together on my plan, will have its ſides eighteen inches, which is equal to ninety cubic feet; whereas, on‘the old plan, forty would be the contents of a beam cut from the ſame tree. Fifty cubic feet would have been cut of as ſlabs, or chopped up for the fire. Such waſte of ſo ſcarce and valuable an article as Engliſh oak merits attention.

The expence of ſawing and putting a beam ofthe above di- menſions together in London would'be as follows, ſawn:on the outſide and one cut each way:

Laisu de Four outſide cuts, taking the mean at 14 inches deep Two breaking cuts— at 18 ditto V1 370 Length 40 feet, 306 feet ſawing, at 7s. bd. per hundred One hundred and twenty 12 inch'dowels, at 1d, each 01070 Boring 240 holes for dowels, and putting together 1 0 £.'210./0

Allówing the fifty fect ſaved to be worth 61. which cut into Rubs would not have been worth more than the labour of pre- paring the twelve inch beam, then the proprietor would ſave 20,

Fig. 5 and 6 are the ſe&ion of a tree quartered that is parallel: there will then be a hollow, all through.

I would recommend the dowels not to go through as thêy would tend to weaken the timber. In an eighteen inch beam X would have the dowels come witfiin three inches of the outer fide, as in Fig. 4. But where a mortiſe is cut, then in place of 2 pin of wood, put in a ſmall bolt of iron with a flat head from the underſide with a fcrew nut on the upper ſide of the beam, to prevent the joint from opening with the preſſure of the tenon z the work to be put together with ſtrong ſcrew cramps, for ſledge hammers and malls ſpvil and bruiſe the wood, and deſtroy the co- hefon of its fibres for 2 cónſiderable depth.

Crooked timber may be converted or applied on the above plan with the difference only that two trees muſt be moulded alike, añd quartered as before, and a right and left oppoſite quarter ſhifted from one tree to thé other. You will then have two beams on the increaſed principle às before, as in Fig. 7 and 8: but one curved beam cannot be made from one curved tée“to have the centérs placed on the outſide, and the dimenſions‘encreaſéd,

By the above method many of our larch fics may be úſed'in building, and the importation of ſo much foreign fir ſaved to this nation.