86 GOODYEAR ON G UM- EL A S TI C. 



THIMBLES. 



Thimbles may be made either of perforated caoutchouc 

 whalebone or ivory, with metal ends. It is supposed, that for 

 cheap thimbles, these substances will be less objectionable than 

 brass or iron. 



SAIL-MAKEKS' THIMBLES. 



The hand pieces of these thimbles are made of perforated 

 vegetable leather, into which the thimble irons are set before 

 the thimbles are vulcanized. 



STEREOTYPE PLATES. 



At the suggestion of another, the writer has made these 

 plates from vulcanized caoutchouc whalebone and ivory, and 

 also from the elastic compound, both of which materials it is 

 confidently expected will be found useful in this art. 



The practical advantages which are to result from this inven- 

 tion for printing books are yet to be determined ; but in other 

 branches of this art, there is no question as to its importance, 

 as in the case of block and cylinder printing for paper-hangings, 

 having the advantage of cheapness, and not being liable to warp 

 or split. The plates may be wound upon drums or cylinders for 

 cylinder printing, without difficulty. 



