SELF-INFLATING PONTOONS. 377 



BATTEAUX AND CANOES. 



Batteaux and canoes of different forms, made of caoutchouc 

 whalebone board, are both light enough to be portable and strong 

 enough for common use. They are constructed upon the same 

 general plan as the other boats before specified, which are made 

 from caoutchouc whalebone and whalebone board, in sheets. 

 See plate , fig. . 



MATRESS BOAT. 



The matress boat is one which, when folded, forms a good 

 ship's matress, and has been noticed as such. Chap. , p. 



SELF-INFLATING PONTOONS. 



These were among the assortment of articles that were exhib- 

 ited at the London World's Fair of 1851, for which a council 

 medal was awarded to the writer. It is a kind of pontoon before 

 alluded to as being an improvement upon those filled with air 

 only. They are made of plated canvas, and are commonly 

 about fourteen feet in length and eighteen inches in diameter, 

 being made either round or square. Each pontoon is composed 

 of from twelve to eighteen separate chambers or compartments, 

 each of these chambers is self-inflated by a separate tube or 

 orifice. It is inflated simply by pulling the ends of the pontoon 

 apart; a sheet of caoutchouc whalebone board, of the size of 

 the pontoon, is cemented in between every two compartments. 

 These boards serve to keep the pontoons from collapsing, and 

 when fitted for use they are prevented from collapsing length- 

 wise, by a spar fastened upon each one or between every two 

 pontoons, when used in pairs. 



