48 TIMBER AND TIMBER TREES. [CHAP. 



other woods ; while, if kept wholly submerged, there is 

 scarcely any limit to its endurance. 



Oak timber' has, however, one drawback. It con- 

 tains a powerful pyroligneous acid, which prevents 

 its general employment in immediate contact with 

 iron, as the metal, whether used for fastenings or other- 

 wise, 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, not- 

 withstanding 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. 



