APPLICATIONS OF TIMBER. 185 



dilk, but its colour is finer, and it does not stain by 

 the contact of iron, which is always the case with oak 

 when moisture p;ets access to it. 



Mahoa,-any is too costly and too ponderous for its 

 streng'th, to be used as a building; timber. But, when 

 well seasoned, it warps and shrinks less by the heat 

 of the sun than any other wood ; and therefore it is 

 the best timber for sign-boards. It is also excellent 

 for doors and window-frames, but too expensive for 

 ordinary occasions. The mahogany from the main 

 land of America is called Bay wood ; and that from 

 the islands — chiefly Jamaica, Cuba, and Hayti — 

 Spanish wood. Before they are oiled or varnished, 

 they are easily distinguished: the pores of bay wood 

 are dark coloured ; those of Spanish seem filled 

 with a chalky matter. 



Fir, Avhen of the best quality, has some advantag'es 

 over oak for the purposes of common building : it 

 is lighter, far more elastic, more easily worked, 

 straighter, and of much greater length. The best 

 that comes in the form of deals is from Christiania 

 and Frederickstadt, chiefly on account of the vast 

 superiority of the saw-mills there. The fir of Nor- 

 way has also been long' celebrated for masts ; and 

 though more weighty, it is far more durable than 

 that obtained from America. 



Applications of Timber. 



The structures in which timber has been employed, 

 which have been, or are, the most remarkable for 

 their magnitude and utility, are roofs of buildings, 

 bridges and piers, light-houses, and ships. For all 

 of these, timber appears to have been principally 

 used before the introduction of any other material, 

 in every place where it could be obtained : and, 

 notwithstanding the use of stone pretty generally 

 for piers, and since the invention of the arch, 



R 3 



