Micro-Metallography. By J. E. Stead. 



271 



polishing engraving plates is substituted. The second block is 

 covered with paper marked "Hubert 0," the third block with 



Fig. 56. 



paper marked " Hubert 000." The fourth block is covered with 

 a ribless cloth of considerable thickness, denseness and texture. 



u 2 



