376 GOODYEAR ON GUM-ELASTIC. 



keep the boat firm without other ribs ; each of the air-chambers 

 is inflated by a separate tube, and upon being distended, the 

 whole boat is self-inflated, and is prevented from collapsing, in 

 the same manner as the other self-inflating air-work pontoons, 

 life-buoys, &;c., which are stayed by whalebone board between 

 the compartments. See plate , figs. . 



TUBULAR PORTABLE LIFE-BOATS. 



Tubular portable boats and life-boats, represented in plate , 

 fig. , are formed of tubes, from one to two inches in diameter. 

 These tubes, which are made of whalebone board, are cemented 

 together lengthwise upon a model of a boat, after which they 

 are stayed, finished, and vulcanized in another model, in the 

 same manner as the ship's boats described, Chap. 

 These boats, in consequence of each tube being made separately 

 water-tight, are more safe as life-boats, besides being stronger 

 than those made of sheets of whalebone, although not so light 

 and portable. 



FOLDING FRAME BOAT. 



This is a form of boat, the frame of which is made of wood, 

 united by joints and hinges, as represented by plate , fig. 

 The cover, which is put on and off" as required, is made of plated 

 gum-elastic canvas. It is light and convenient, but somewhat 

 objectionable, chiefly on account of the number of pieces and 

 joints in the frame. It is rendered a safe boat, or life-boat, by 

 air-chambers cemented to the top of the cover. See plate , 



BOX BOAT. 



This boat is made of caoutchouc whalebone in two equal 

 parts, which may be connected by hinges and shutter bolts. 

 When shut together, they form a serviceable box or trunk. See 

 plate , Chap. 



