14 



STRUCTURE OF VESSELS. 



they in tui'ii become lowermost ; and by the influence 

 of rather close plantation, which of itself will perform 

 in a natm'al manner all that we have been teaching 

 by art, and will perform it well. This closeness 

 must, however, be very guardedly employed, and 

 timeously prevented from proceeding too far, other- 

 wise the complete ruin of the forest, by prematm'e 

 decay or winds, may ensue, especially when it con- 

 sists of pines. Of course all kinds of pines require 

 no other attention than this (well-timed thinning), 

 and to have their sickly moss covered under branches 

 swept clean down. 



SECTION II. TIMBERS. 



Timbers, as before stated, are the ribs of the ves- 

 sel, spreading out and upward (excepting at the bow 

 and stern) at right angles to the keel and keelson, 

 two large straight logs which form a double spinal 

 support or backbone. The ribs or compass timbers 

 in great public building establishments are some- 

 times bent by machinery, after being softened by 

 steam or hot liquids * ; and for this pm*pose the 



* We are not in possession of sufficient facts to judge of the 

 effect to hasten or deter decay occasioned hy the timber having 



