Timber that is to lie in mortar--as, for instance, the ends of joists, door sills and frames of doors and windows, and the ends of girders--if pargeted over with hot pitch, will, it is said, be preserved from the effects of the lime. In taking down, some years since, in France, some portion of the ancient Château of the Roque d’Oudres, it was found that the extremities of the oak girders were perfectly preserved, although these timbers were supposed to have been in their places for upwards of 600 years. The whole of these extremities buried in the walls were completely wrapped round with plates of cork. When demolishing an ancient Benedictine church at Bayonne, it was found that the whole of the fir girders were entirely worm eaten and rotten, with the exception, however, of the bearings, which, as in the case just mentioned, were also completely wrapped round with plates of cork. These facts deserve consideration. If any of our professional readers should wish to try cork for the ends of girders, they will do well to choose the Spanish cork, which is the best. In this place it may not be amiss to point out the dangerous consequences of building walls so that their principal support depends on timber. The usual method of putting bond timber into walls is to lay it next the inside; this bond often decays, and, of course, leaves the walls resting only upon the external course or courses of brick; and fractures, bulges, or absolute failures are the natural consequences. This evil is in some degree avoided by placing the bond in the middle of the wall, so that there is brickwork on each side, and by not putting continued bond for nailing the battens to. We object to placing bond in the middle of a wall: the best way, where it can be managed, is to corbel out the wall, resting the ends of the joists on the top course of bricks; thus doing away with the wood-plate. In London, wood bond is prohibited by Act of Parliament, and hoop-iron bond (well tarred and sanded) is now generally used. The following is an instance of the bad effects of placing wood bond in walls: In taking down portions of the audience part and the whole of the corridors of the original main walls of Covent Garden Theatre, London, in 1847, which had only been built about thirty-five years, the wood horizontal bond timbers, although externally appearing in good condition, were found, on a close examination by Mr. Albano, much affected by shrinkage, and the majority of them quite rotten in the centre, consequently the whole of them were ordered to be taken out in short lengths, and the space to be filled in with brickwork and cement.