Being thus sawn through the heart, the air will rapidly absorb the juices, and such a seasoning may be soon effected as will, I have no doubt, completely prevent the dry rot. But my object in this place is to show the economy of the plan in a mechanical point of view. By thus sawing a log through the middle, two timbers are immediately provided instead of one, and both of one precise mould. Thus when the pieces a a in the above figure are placed end to end, they will form two timbers exactly similar, as appears by the annexed figure. The expedition gained by this method of converting timber is obvious; every ship-builder is fully sensible of the difficulty he is often put to, and of the sad waste of time and labour often incurred in preparing two such timbers to match one another. It not unfrequently happens that the framing of a ship stands still for several days owing to this circumstance. The saving of time and labour is in consequence an important saving in the expense of building. I have also proved by experiment that this mode of sawing the timber down the middle confers great additional strength. From the same bough I cut two pieces of the same length and thickness; one of them I squared according to the usual plan, which I condemn, the other, according to my prc posed method, leaving the circular sides, as shown at a a in the foregoing figures. The proportional strength of only one of the pieces I found to be as 25 compared to 27, the strength of the whole square timber; the strength of the two pieces, therefore, makes the difference of 50 to 27, or nearly double ; in addition to which advantage, far greater durability will be obtained by the prevention of the dry rot. For the timbers of a 74-gun ship, logs of 22 inches diameter are usually employed ; if these, instead of being squared, are divided according to my method, their strength and width of bearings for the planks will be fully adequate, and the little difference of strength may be easily com pensated by two or three more timbers, for which there will be plenty of room, and the saving of expense will thereby be immense. By the most accurate
calculations that I have been enabled to make, I find the saving in timber only to be full one-third. The annexed sketch represents a horizontal section of a small portion of a ship's side, with the arrangement of the timbers accor ding to my plan. a a a, three of the ship's timbers ; b b b b, the fittings made from the slabs before mentioned, which are uniformly of a suitable shape; c c are air passages, which serve effectually to carry off whatever moisture may remain in the timber, the hearts of the trees being exposed to the air. It will likewise be perceived that the circular form of the grain being retained, the strength of the timber is better preserved than if the logs were squared, as I have proved by the before-mentioned experiment. From long observation and repeated investigation I am indeed convinced that the outside, or younger part of a tree; is stronger, more durable, and more seaworthy, than the heart, notwithstanding I have daily witnessed the preference given to the latter, while the former has been used for fuel. In the repairing and breaking up of ships, it will be almost invariably found that the decayed planks have the heart of the tree, and the sound ones, not ; it follows, therefore, that the present system of lining is very defective. To lessen the charge of carriage, it is not unusual to side the logs where the trees are felled. Now, if the trees were also sawn down the middle in the forest, an increased facility of removal would be acquired, and the timber would be seasoning, and probably be fit for use, ere it came into the dock-yard. The longer a tree remains whole after it is felled, the more sap It will contain, and the more rapid will be its decay. I have seen many trees that were sound when felled, decay from the heart outwards, owing to their lying a long time with their ,juices shut up in them. The dividing of the trees would have preserved them."