Page:Timber and Timber Trees, Native and Foreign.djvu/68

48 other woods ; while, if kept wholly submerged, there is scarcely any limit to its endurance. Oak timber' has, however, one drawback. It contains a powerful pyroligneous acid, which prevents its general employment in immediate contact with iron, as the metal, whether used for fastenings or otherwise, is subjected to a rapid corrosive action, while the timber is also liable to suffer by waste and deterioration.

British Oak timber has, for ages past, been a most important article in ship-building in this country, and it is still used for this purpose to a very great extent, notwithstanding the present very general use of iron as a substitute for it.

It was only within the last few years, that it was felt the quantity of Oak produced in England would soon be inadequate to meet the great and increasing demand for it, and that it was necessary efforts should be made to supplement it by the introduction of foreign Oaks and other hard woods for ship-building purposes.

To show this great necessity it will be sufficient to state, approximately, the store of ship-building timber which it was thought necessary to maintain at Woolwich Dockyard in the several quinquennial periods of the quarter-century ending in 1865. It will, apart from the ordinary demands of the private trade, serve to illustrate in some degree how large must have been the supplies annually required for all the royal dockyards, taken collectively, in order to replace the ships that were worn-out or had become obsolete, and to keep the ships of the royal navy up to the strength called for by the times.