vui.] OAK TIMBERS. 97 



curring some risk to the stability of the work ; but when 

 once its moisture is completely evaporated, few woods 

 are liable to so little change, particularly when employed 

 in situations where it is protected from the influence of 

 moisture or draught. If subjected to alternations of 

 wet and dry, it withstands the change better than most 

 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, 

 notwithstanding the present very general use of iron 

 as a substitute for it. 



It is only within the last few years that it has been felt 

 that 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 



* This stock, I am informed, is now all gone, and very little Oak is now 

 bought for the royal dockyards. The illustrative statement retained, there- 

 fore, is merely matter of history now. 



H 



