2 T\\OK\\ Japanese ''Magic" Mirrors. 



" away rather more than the thin parts, and remain rela- 

 " tively concave, or at least less convex." 



It would appear from this explanation of the produc- 

 tion of the reflecting surface of Japanese mirrors that 

 " scraping " tools are necessary, or, at least, it is not 

 suggested that the "magic " effect may be produced in any 

 other way. 



With a view to test the effect of simply grinding and 

 polishing the surface, a casting vvas made of hard bronze 

 (about y2)% copper, 23% tin, and 4% zinc) from a Japanese 

 mirror having the magic properties in a slight degree, the 

 surface being protected by a sheet of paper during the 

 process of moulding, which was done in sand in the usual 

 way. The replica was not very perfect, but, as it was only 

 required to experiment upon, the few sand holes on the 

 plane surface were of little consequence. 



The surface was now ground with various grades of 

 emery, the grinding tool, a lead block some 5 in. diameter 

 and ;34^in. thick, being uppermost. As it approached a 

 surface fine enough for commencing the polishing process, 

 the workman who was engaged upon it, on his own 

 account and contrary to instructions, finished the grinding 

 with cross strokes only. The slight roughness of surface 

 left by this procedure was partially removed by fine 

 grinding, but the effects remaining were plainly to be 

 seen after polishing, on reflecting a beam of light, and a 

 very good example was thus afforded of the effect of a 

 very small irregularity of surface. 



Polishing with rouge was now commenced, and, this 

 proving a very slow process by hand, a machine vvas 

 roughly fitted up for the purpose. The polishing block 

 was simply a large cork, some 3 inches in diameter, 

 covered with felt and then with chamois skin, and the 

 weights used varied from 2 to 6 lbs., the heavier the better, 



