266 GOODYEAR ON GUM-ELASTIC. 



are called, " Life-Preservers." Notwithstanding the price has 

 been reduced to one-half what it was, yet the demand and sale 

 of them is not half so great as it was fifteen years ago. 



One great difficulty in making life-preservers, as well as every 

 other description of air-work, to answer the purpose for which 

 it is designed, has been the impossibility of uniting India rubber 

 to metal, and none but metal tubes have, heretofore, been used 

 for inflating them. Although when first made with these tubes 

 they may be tight, very often, after a little wear, the air escapes 

 between the gum and the metal. By the invention of the gum- 

 elastic tube, (which is also self-acting, and much more safe on 

 that account, and which can be made for a trifle in comparison 

 with the metal tube,) this difficulty with metal tubes is completely 

 obviated. 



By removing the defects which have been enumerated, by the 

 improvements treated of in this work, it is hoped that gum-elas- 

 tic life-preservers, which are really of great value, if well made 

 and properly used, may be made great blessings to mankind. 



LIFE-PRESERVERS. 



The kinds of life-preservers with which the market has been 

 chiefly supplied, are represented by figs. 1, 2 and 3, in plate xxvii. 

 They are less safe than any of the other patterns that are 

 represented in the plate. The article represented by fig. 4, is 

 after the same pattern as fig. 1, made in the same way, except 

 that the compartments do not communicate, and they have each 

 a separate tube. This arrangement, which is a consequence of 

 the invention of the self-acting gum-elastic tube, makes life-pre- 

 servers, filled with air only, comparatively safe, although they 

 are more troublesome to inflate than the self-inflating air-work. 

 The metal tubes formerly used would not only be too heavy, but 

 quite too expensive for such an arrangement with many tubes, 

 even if there was no other objection to their use. 



