216 CERTAIN SAND MOUNDS OF 



supply of staple sizes for commercial purposes been stamped from sheet metal by 

 the Whites, exact duplicates must necessarily occur in the mounds. 



3. Stria? in depressed surfaces, giving evidence of the conferring of the design 

 by pressure and motion as shown in the paper of Professor Cushing. 



We are, therefore, of the opinion that aboriginal workmanship on the copper 

 of the river mounds maj' be conceded. 



SHEET COPPER OF ABORIGINAL PRODUCTION. 



But here we are brought face to face with another question. It has been 

 alleged by some that, granting aboriginal work on copper, the sheets of metal may 

 have been obtained through White contact, a suggestion too plausible to be dismissed 

 without serious consideration. 



We shall first consider the mechanical evidence of aboriginal work. 



The sheet-copper ornaments do not present a uniform thickness, as would be 

 the case had the metal been rolled or hammered by European artisans and stamped, 

 the same specimen sometimes decreasing in thickness to almost a cutting edge on 

 one side. Moreover, a number of plates give evidence of a species of patchwork 

 where smaller sheets are joined together to furnish one of the requisite size. 

 While present in a number of cases, this curious aboriginal custom is especially 

 emphasized in the case of the copper breast-plate found by us at Mt. Royal. 



This breast-plate, it will be recalled, was exhumed from the great Mt. Rojal 

 mound at a depth to guarantee original deposit. 



We have requested Dr. M. G. Miller, who was present at the discovery of 

 all the copper met with by us, carefully to examine and to describe the two copper 

 plates constituting the breast-piece, one of which was figured as frontispiece of 

 Part I, while the representation of the other occupies a similar position in this 

 volume. 



"The two plates of copper composing the chest-piece were each about 10'5 

 inches square, and when found were separated by a woven vegetable fabric. 



" The anterior plate, restored in the frontispiece of Part I, unfortunately, is 

 now in such a fragmentary condition that a complete description of its structure is 

 impossible. Moreover, a thick coating of carbonate upon the surface of the frag- 

 ments adds to the difficulty. On certain pieces this coating presents a delicate hair- 

 like structure, suggesting the idea that the surface had been in contact with the 

 skin of some animal, but inspection under the microscope shows it at present to 

 consist of capilliform crystals. 



'•The decoration is impressed and is regular and well defined. It consists of 

 seven concentric circles surrounding a central perforation, and a conventional 

 aboriginal bird's head occupying the space between the circumference of the outer 

 circle and each corner. Between each head and its neighbor is a diagonally placed 

 elliptical figure. The edges of the decoration are slightly rounded and not sharply 

 cut as represented in the frontispiece. The impression varies somewhat in depth, 

 its maximum being about 2 mm. 



