116 Economy of Machinery and Manufactures. 



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the instrument or tool actually producing the work, shall cost even 

 five or ten thousand times the price of each individual specimen of 



its power. 



Operations of copying are effected, by printing from cavities; by 



printing from surface ; by casting ; by moulding ; by stamping ; by 



punching ; with elongation ; and with altered dimensions* 



The art of printing, in all its departments, is essentially an art of 

 copying. Under its two great divisions, from hollow lines, as in 

 copper-plate, and from surface, as in block printing, are comprised 

 numerous arts. Printing from cavities comprises copper-plate and 

 steel-plate engravings, music printing, calico printing from cylinders, 

 and printing froti} perforated sheets of metal, or stencilling. 



The second department, i. e. printing from surface, is of more fre- 

 quent application in the arts, and comprehends printing from wooden 

 blocks, from movable types, from stereotype, calico printing from 

 blocks, printing oil cloths, letter copying, printing on china, lithograph 

 and register printing. 



Before proceeding to the consideration of any of the other modes 

 of copying, the manner of forming the pattern or block for surface 

 printing and lithograph, will be quoted in the words of the author. 



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design being sketched upon it, the workman cuts away, with sharp tools, every part 

 except the lines to be represented in the impression. This is the reverse of engra- 

 ving on copper, on which every line to be represented is cut away. The ink, in- 

 stead of filling the cavities cut in the wood, is spread upon the surface, and is thence 

 transferred to the paper. In lithographic printing, the original is a drawing made 

 on a stone of a slightly porous nature ; the ink employed for tracing it, is made of 

 such greasy materials, that when water is poured over the stone, it shall not wet 

 the lines of the drawing. When a roller covered with printing ink, which is of an 

 oily nature, is passed over the stone, previously wetted, the water prevents the ink 

 from adhering to the uncovered portions; whilst the ink used in the drawing is of 

 such a nature, that the printing ink adheres to it. In this state, if a sheet of paper 

 be placed upon the stone, and passed under a press, the printing ink will be trans- 

 ferred to the paper, leaving the ink used in the drawing still adhering to the stone. 

 « A few years ago, one of the Paris newspapers was reprinted at Brussels, as soon 



as it arrived, by means of lithography. Whilst the ink is yet fresh this may be easily 

 accomplished. It is only necessary to place one copy of the newspaper on a litho- 

 graphic stone ; and by means of great pressure, applied to it in a rolling press, a 

 sufficient quantity of the ink will be transferred to the stone. By similar means the 

 other side of the newspaper may be copied on another stone, and these stones will 

 then furnish impressions in the usual way." 



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Of " copying by casting," an art so extensively useful, and yet so 

 familiarly understood, no illustration need be quoted in this place, 

 except one, which is so extremely new and curious, that it cannot 

 fail to be interesting. 



