Figure i I . — Engraving produced from siderographically prepared plate. 

 The scroll work was done on a Spencer lathe. The original designs and 

 medallions were first transferred to soft steel rolls. These rolls, after hardening, 

 were used to impress the final plate, also of steel, which was then hardened 

 for final use. The ability of the siderographic roll to impress the same design 

 several times in the final plate is here demonstrated. From London Journal 

 oj Arts and Sciences (1820), ser. i, vol. 1. 



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