SCIENCE IN THE INDUSTRIAL WORLD 



sented in some such ratio as that of minutes to hours. 

 This being the case, it will be readily understood that, 

 from the commercial point of view, the wood-engraving 

 must go out of existence. It has one advantage, aside 

 from its mooted artistic superiority over certain forms 

 of photographic engravings, in that it may be printed 

 with reasonably good results on cheap paper and repro- 

 duced an almost endless number of times without deteri- 

 oration. For this reason, in cases such as illustrations 

 for advertising purposes, etc., in newspapers, which are 

 to be repeated day after day in millions of impressions, 

 the wood-engraving is still used, the elements of time 

 and cost of production being unimportant. On the other 

 hand such engravings have little advantage for such 

 purposes over the modern "zinc etching," or "zinco," 

 as it is vulgarly called, to be referred to more fully in a 

 moment, which may be produced so much more quickly 

 and inexpensively. 



COPPER- AND STEEL-PLATE ENGRAVINGS 



Shortly after the time of the introduction of the wood- 

 engraving, and possibly at a much earlier period in its 

 crudest form, reproduction of pictures made from 

 engraved metal plates came into use. The method of 

 engraving such plates and of printing them was exactly 

 the converse of the process of wood-engraving, although 

 this is not shown in the finished prints. In the wood- 

 engraving the part of the surface designed to make the 

 impressions of the ink upon the paper is the part left by 

 the engraver, the hollowed-out part between the lines not 



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