BARRON, ON THE DRY UOTv 149 



to be comparatively sound.* A particular illustration of this truth 

 is seen also in the excellent preservation in which the cabin furni- 

 ture and joiners' work of ships, such as birth boar<ls, &c. are found, 

 arising from the (ree ventilation of those apartments, and their re- 

 moteness from the source of the noxious air generated by the bilge 

 water. I would not be understood as ascribing this destructive 

 agency directly to the bilge water itself, for it is well known that 

 those parts of the timbers which are always covered with it, are 

 seldom known to decay, while those immediately above it are most 

 injuriously aiJected by tlie noxious air arising from it." 



" Every ship or vessel acts, in some degree, as an hydraulic bel- 

 lows, according to the quantity of water allowed to remain in her 

 after the pumps have sucked ; for as this water, by the motion of 

 the vessel, rolls from side to side, tlie air above it, is by its motion, 

 alternately forced out and drawn in between the timbers," 



" It may not be irrelevant heie to observe, that the tightness of 

 ships is a fruitful cause of the destructive atmosphere of which T 

 am speaking; for there is not an instance of the sudden decay of 

 a ship that has proved leaky the first three or four years of her 

 running, and this can only be accounted for by the continual use 

 of her pumps, constantly admitting a quantity of pure water, and 

 again removing it before it can become impiegnated with tlie pro- 

 perties of the wood and the metallic substances, from which it de- 

 rives its destructive qualities." 



The ventilation is propc^sed to be accomplished by bellows con- 

 structed like the common smith's bellows, and to be worked by 

 liand ; all modes arising from the motion of the vessel having beer^ 

 found altogether uncertain. A pipe leads down from the valve on 

 the under side of the bellows, and is, at the bottom, connected 

 with another pipe passing fore and aft the vessel, and opening by 

 means of short pipes into the spaces between the timbers, these 

 short pipes being made to pass through the limber boards for that 

 purpose. 



The Commodore has found that the odour from a small quantity 

 of any suitable substance deposited in ihe hold, may in a few se- 

 conds be perceived upon ihe deck, when the bellows arc worked. 



Of the Building of Ships. 



" In the preceding pages I have intimated, that in order to the 

 beneficial operation of the air-pumps or bellows, and to prevent 

 the secretion of the destructive air, v/hich the machine is intended 

 to extract, ships should undergo a considerable ch*(nge in their 

 construction. 



" I have submitted my ideas on this subject to several of our 



* " Eij]fht years after the fripate United States \;'as launched, I visited 

 her, and found all the materials unconnected with the intcrnni air, (that 

 ia, that air between the inside and outside plank,) as perfectly sound :\b 

 they were when I first joined her in '98 : I served on board of her for two 

 years, and could readily identify the articles alluded to. At the tiine 1 

 speak of, the United States had undergofie one thorough repair and was 

 eqnally ready for the second " 



