AC2 



KNOWLEDGE. 



Df.cembf.r, 1911. 



lights. The mesh of the screens 

 ranging from fifty hnes to tiie 

 heavy or rough printing 

 to four hundred Hnes 

 to the inch for the 

 most careful and finest 

 art printing. T li e 

 most useful screens 

 have one hundred and 

 twenty, one hundred 

 and thirt\-three and 

 one hundred and fift\- 

 lines to the inch, and 

 these are, as a general 

 rule, the sizes used in 

 connection with illus- 

 trations for magazines. 

 In the case of the 

 dailv papers — which 

 are very rapidly 

 printed on fast-running 

 machines — the illus- 

 trations require screens 

 with a much more 

 open mesh — usually of 

 from seventv - five to 

 one hundred lines to 

 the inch. If t h e 

 reader will examine 

 one of the illustrations 



\aries much — 

 inch for \'er\' 



requn-ed distance from 

 kind of ■■ dot " desired- 



I'lGL'Ki; ,s. The Etching K.ith. 

 Examining the plate for depth. 



the plate — so as to gi\'e the 

 die makes his first exposure, 

 which is to give the 

 ■■ dot " formation in 

 the darker parts of 

 the subject. He then 

 places the cap on the 

 lens, puts in a larger 

 stop and exposes again. 

 He, in this wa\', gets 

 a " dot "' formation of 

 the detail. The third 

 exposure — with a still 

 larger stop — is for the 

 "dot" formation in 

 the high lights (see 

 enlarged illustration of 

 the screen effect in 

 Figure 4). Some 

 operators make only 

 two exposures. The 

 different stops used vary 

 a great deal. Some 

 operatxirs favour one 

 kind — others another. 

 The writer uses three 

 kinds — a verv small one 

 to gi\e the "dots"' in the 

 blacks, one about three 

 times as big to give the 



ElGURE 9. A Fine Etcher at Work. 

 "stopping out.'' 



En, LKi. 10. EngruN iiig the Plate. 

 ■' Taliing out blemishes." 



in this magazine under a strong magnifying glass detail, and a square one, about three times the size 



he will see how the picture is formed by the " dots " of the one last mentioned, for the high lights. 



and squares. The exposures are \ery short — whichever of these 



When the operator has adjusted the screen to the stops are used. Their w hole aggregate length — from 



