PBOCEEDINGS OF THE NATIONAL MUSEUM. 



477 



of the same object and exhibits more graphically the manner in which 

 the edges of the copper plates are thinned ont and tnrned nnder all 

 ronnd to prevent their falling off. 



Fignre 3 shows the second bird with one wing cover removed. Here 

 is to be observed the careful manner in which the ujiper 

 surface of the wing was carved to shape and smoothed 

 down. The copper plate is warped so as to lie in con- 

 tact with this surface at every point. The removal of 

 the plate and the examination of the reverse side, sliown 

 in figure 4, reveal the metallurgic processes employed. 

 It will be seen that neither punch nor severe pres- 

 sure produced the marks on the outer surface. The 

 marks on both examples were cut with metal tools. 

 These specimens have both been examined by a skill- 

 ful engraver and they have given evidence of having 

 been cut and scraped as indicated above. 



Fiii. 4. 



COPPEU WING 

 COVER. 



