"Well-squared timber," as understood in the trade, is nearly die square, and admits of little wane on the angles at any part of the log. The yield of this is about '68 per cubic foot of raw material, as shown in the table against Tewart. Some woods, when exceedingly well squared, will often yield a little more; as Mexican Mahogany. Others again, which are imperfectly manufactured, yield considerably less per cubic foot; as African.
The figures against Oak, English, were obtained from the conversion of both " rough " and " sided," not square timber. Also the figures against Elm, English, were obtained from " rough," and not square timber.
The results given in the table were obtained from the conversion of timber for ship-building at Woolwich Dockyard. For civil architecture and engineering purposes the yield per cubic foot would probably be better, as there would be less waste in cutting to straight than to curved lines.
The advantage of the table will be manifest on trial, since, if the figures in column A, which stand against any one of the woods mentioned in the list, are used as divisors of the net quantity of converted timber material required for any purpose, the quantity of hewn or square timber, i.e., raw material, which it is necessary to purchase to produce it, is readily found.
Example:—If 5,600 cubic feet of converted timber material (Dantzic Fir) are required, how much hewn or square timber will it be necessary to purchase to produce it?
In column A, against Dantzic Fir, is 700; therefore 5600700 = 8,000 cubic feet.
Also, if the figures in column A are used as multipliers, the converted produce can be ascertained
