58 ANNUAL OF SCIENTIFIC DISCOVERY. 



same amount which Mr. Hoe's press supplies in one hour ! Thus his 

 press accomplishes as much as it would take the half, at least, of the 

 whole French army to supply !" 



CHEMITYPE PRINTING. 



ANOTHER species of engraving has been brought before the public, 

 to which the name of Chemitype Printing has been given. By this 

 method an etching or engraving, made in metal in the usual way, 

 may be converted into a high-relief stamp, to be used in printing on 

 an ordinary press, as is the case with common wood-engravings. 

 The following statement may in general illustrate the character or the 

 invention. On a highly polished plate of pure zinc an etching or 

 engraving is made in the usual manner, which, under common cir- 

 cumstances, would be fitted for impressions on an engraver's press, 

 having the same harmony and proportion of all the respective etch- 

 ed or engraved lines. The tracery, thus deepened, is now to be fused 

 or melted down with a negative metal, and the original metal plate 

 (zinc) corroded, or etched, by means of a certain acid, thus making 

 the characters of the former drawing appear in the shape of a high- 

 relief stamp. This effect is only produced in consequence of the 

 metal composition in the lines of the tracery not being acted upon by 

 the acid, on account of the galvanic agency subsisting between the 

 two metals, and the acid corroding only the zinc. 



After these details, there cannot be the least doubt of the specific 

 difference between the chemitype printing and glyphography, relief 

 etching in copper, and other similar artistical processes and practices 

 lately invented. Its principle rests upon the positive and negative 

 nature of the metals. As every drawing on the metal plate is com- 

 pletely exact on the relief stamp, the practice is absolutely independ- 

 ent; the exact and accurate representation of the original sketch is 

 always to be expected. Wood-engraving cannot, in most cases, be 

 superseded by this novel method; but in many other instances the 

 new practice is preferable, chiefly when colored printing is required, 

 in the representation of maps, plans, architectural drawings, &c. &c. 

 At the same time, the correction or improvement of any drawing can 

 be much better executed than in wood-engravings. Scientific Ameri- 

 can. . 



IMPROVED MACHINE FOR PRINTING WALL-PAPER. 



THE inventors of this new machine for printing wall-paper, oil-cloth, 

 &c., are Messrs. Gould & Shaw, of Newark, N. J. The machine is 

 so made as to give to two blocks, placed in two plattens, an intermittent, 

 reciprocating motion, so that two impressions are made during the for- 

 ward and backward stroke of the piston that moves the blocks. It 

 also supplies the blocks with color from two boxes, as well as feeds in 

 the paper or material to be printed, and takes it away. The principal 

 machinery consists of two long tables, transverse to each other, one 

 being the feeding-table, and the other the printing-frame. At the end 



