■ii.rKi-: 1. 



The Cameras and methods of illumination. 



THE PROCESS BLOCK. 



Bv H. E. RE A. 



Process blocks are tised now for pn 

 trations in all sorts of periodicals — in tl 

 newspaper, as well as in 

 the finest hook or art 

 catalogue. 



A block must he made 

 capable of printing side 

 h\' side with type, and 

 it must he able to gi\'e 

 all the range of tones 

 of the original from black 

 to \\ hite. It is made to 

 do this h\- having its 

 surface cut up into a 

 very large number of 

 "dots" or squares — so 

 small as to he, as a 

 general rule, unnoticed 

 hv the naked eye — which 

 catch the ink when the 

 roller goes over them 

 and which immediately 

 afterwards print the 

 picture. 



The block-maker has 

 first to consider — when 

 he gets the photograph 

 or drawing which is to 

 be reproduced — what 

 sort of jiaper the block 

 whether rough or with 



nting illus- 

 ialfpenn\' 



art paper. 



is the nimilxr 



Th 



i^i* 



FlGlKI. 2. '1 he LauiLia witli tlie screen ni (m.^uinn 



is to be 

 smooth 



used upon, 

 surface, or 



better the paper is, the greater 

 "dots" which can be made and 

 the closer they will be 

 together. The original 

 is then pinned up on 

 the cop\ing - board (see 

 Figure 1), which is illu- 

 minated by two power- 

 ful arc lamps, and a 

 photograph is taken of 

 it. which may reduce 

 or enlarge it. according 

 to the size of the block 

 wanted, and which, at 

 the same time, brings 

 the " dots " into exist- 

 ence. This photograph 

 may be taken by means 

 of the wet collodion 

 process, the collodion 

 enudsion process or on 

 a dry plate. In the first 

 twd cases the operator 

 ^ has to prepare his own 



.-tV^^ j plates, but dry plates made 

 iL XjJ^jjrr especially for process- 

 ■^^ ^^^ ■ workers can be obtained 

 from the dealers. The 

 writer uses dry plates. 

 The " dots " are obtained by interposing in the 

 camera, between the photographic plate and the lens, 



460 



