1907] BRIEFER ARTICLES 61 
is available therefore for plates only. It is not an expensive process 
and gives better results than zinc etchings. It is recommended whenever 
plates are required. The drawings must be of the same kind as for copper 
and zinc etchings (see 5). 
Examples:—35: pls. 4, 5; 36:pls. 17-20 (printed in paler tinted inks); 
37: pls. 14, 15, 26, 27; 38: pls. 1-4; and especially 42: pls. 19-28. 
3. Photogravures——These are printed from an etched metal plate or 
from relief plates, the design being reproduced by rather elaborate mechan- 
ical and photographic means. The process is unsuited to anything but 
plates; and as the prints must be made separately on hand-presses, photo- 
gravure is expensive, costing three to four times as much as photolitho- 
graphs, zinc or copper etchings, or half-tone work. The advantage is 
that photographs and all kinds of drawings (whether in ink, crayon, or 
pencil; whether in line or tint or wash) can be reproduced with the utmost 
fidelity, with an almost perfect rendering of tone and of light and shade. 
Pencil drawings, however, may be too weak in contrast to permit effective 
reproduction; and inasmuch as contrast is always somewhat reduced, 
shaded drawings should show a little more than is desired. 
Examples:—33: pl. 1 (from pencil drawings); 34: pl. 17 (from pen 
and wash); 37: pls. 11-13 (from pencil and wash); 38: pls. 6, 7 (from 
pencil, background removed). 
4. Half-tones—These are relief plates, usually of copper, in which 
the “grain,” instead of being of almost imperceptible dots irregularly 
distributed as in photogravure, is produced by a screen of ruled lines, 
Whose intersections form equally spaced dots, isolated, or blended with 
others into irregular lines or surfaces. Half-tone work is adapted to 
photographs and to varied styles of drawing, like photogravure; but as 
the “‘grain” is coarser it does not equal that process in delicacy or range. 
Yet when the screen used is fine and the workmanship first class, the 
results are almost as good. It has the very decided advantage that the 
metal plate may be mounted on a block and may then be printed along 
with type. It is necessary, however, to use a very smooth paper, either 
highly calendered or coated with clay. The coated papers are believ 
to be not durable and are to be avoided whenever possible. 
Half-tone work alone is available for reproducing photographs to be 
printed in the text. Good prints (not negatives) are needed, showing 
sharply the details desired. Almost any sort of print can be reproduced; 
t engravers prefer, doubtless from habit, those made on Solio pees, 
toned brown. In case any painting-out of defects or background is to 
be done, unglazed prints are preferable. 
