GLTPHOGRAPHY. 81 



produce this depth. This part of the process is purely mechanical, 

 and easily accomplished. 



" It is indispensably necessary that the printing surfaces of a block 

 prepared for the press should project in such relief from the block 

 itself as shall prevent the probability of the inking-roller touching 

 the interstices of the same whilst passing over them : this is accom- 

 plished in wood engraving by cutting out these intervening parts, 

 which form the lights of the print, to a sufficient depth ; but in 

 glyphography the depth of these parts is formed by the remaining 

 portions of the white composition on the plate, analogous to the 

 thickness or height of which must be the depth on the block, seeing 

 that the latter is, in fact (to simplify the matter), a cast or reverse, of 

 the former. But if this composition were spread on the plate as 

 thickly as required for this purpose, it would be impossible for the 

 artist to put either close, fine, or free work thereon ; consequently 

 the thinnest possible coating is put on the plate previously to the 

 drawing being made, and the required thickness obtained ultimately 

 as described. 



" The plate thus prepared is again carefully inspected through a 

 powerful lens, and closely scrutinized, to see that it is ready for the 

 next stage of the process, which is, to place it in a trough, and sub- 

 mit it to the action of a galvanic battery, by means of which copper 

 is deposited into the indentations thereof, and, continuing to fill them 

 up, it gradually spreads itself all over the surface of the composition 

 until a sufficiently thick plate of copper is obtained, which, on being 

 separated, will be found to be a perfect cast of the drawing which 

 formed the clichee. 



" Lastly, the metallic plate thus produced is soldered to another 

 piece of metal to strengthen it, and then mounted on a piece, of 

 wood to bring it to the height of the printer's type. This com- 

 pletes the process, and the glyphographic block is now ready for the 

 press. 



" It should, however, have been stated previously, that if any 

 parts of the block require to be lowered, it is done with the greatest 

 facility in the process of mounting." 



This process has, however, not come into much use, as a substi- 

 tute for wood engraving, in consequence of the impossibility of 

 finding a suitable varnish for the use of the artist or engraver. 

 It has, in fact, given way to another process, also embraced in 

 Mr. Palmer's patent, which is worked thus: A copper plate is 

 etched by the process commonly employed by engravers, the lines 

 being cut into the copper with a bold stroke. The lines are then 

 bitten deeper by nitric acid. The etching is made direct, not 

 reversed, as it is upon a plate that is to be worked at the copper- 

 plate press. When the engraving is ready, the etching varnish 



G 



