TURTLES. 47 



to be easily detached from each other. A plate 

 varies in thickness from an eighth to a quarter 

 of an inch, according to the size and age of the 

 animal. 



For the following account of the manner in 

 which this beautiful material is rendered available 

 to the many purposes of use and ornament which 

 it subserves, we are indebted to the history of 

 British Reptiles by Professor Bell. 



" The scales, or plates, are in the first place 

 separated by the application of heat. They are 

 sold to the manufacturers in the rough state, in 

 which they are uneven, fragile, opaque, and dirty ; 

 and it is the first object of the artificer to obviate 

 these defects. The uneven surface, the irregular, 

 curvature, the unequal thickness of diff'erent 

 parts, have all to be corrected : and not only can 

 these objects be readily effected, but the sub- 

 stance can be rendered ductile, compressible, ca- 

 pable of receiving any impression, of being carved, 

 moulded, and polished, and even extended by 

 soldering pieces together by means of their own 

 substance reduced to powder. The whole of 

 these processes are performed by means of heat. 



" The uneven curvature is first of ^all to be 

 removed, and the plate rendered perfectly flat. 

 This is effected by immersing it in hot water, 

 and then allowing it to cool under heavy pres- 

 sure, between smooth blocks of wood, or metallic 

 plates. The surface is then rendered smooth, 

 and the thickness equal, by scraping and filing 

 away the rough and prominent parts. In this 

 way each plate receives an equal and smooth sur- 

 face. But it is in many cases desirable to employ 

 larger pieces than can be obtained from single 



