62 " BOTANICAL GAZETTE [JANUARY 
If wash or pencil drawings are to be reproduced, contrast should be 
greater than desired, since there is necessarily a light gray background 
representing the whites of the picture. Except when figures have too 
intricate outlines this background can be cut away. 
Examples :—35: 198-207; 38:48-57; 37:304-5 (which shows what 
can be done with simple apparatus by cutting away and vignetting the 
background); 39: pl. 8 (pencil drawing, background cut away); 39: 
pl. 4 (2d issue; from water color); 41: pls. 1, 2 (from photomicrographs; 
_ compare wth photogravure from similar originals, 32: pls. 15-17); 41° 
pls. 3, 4 (from pen and pencil, line and stipple, combined with wash; 
compare with potogravure from similar original, 37: pls. 11-13). 
5. Copper and zinc etchings.—All the previous processes are as truly 
dependent on etching by some solvent as are these. The term is used to 
distinguish the copper or zinc plates, made without grain or screen, mounted 
type high and intended for printing on an ordinary press. Copper is 
used for the finer and more delicate work; zinc where the work is bold. 
Naturally the copper block is the more expensive. This process is in all 
ways the one best suited to reproduce drawings for text use. It is also 
satisfactory for plates; indeed there is scarcely any work that cannot be 
adequately and conveniently illustrated by it, if only the drawings are 
made with reference to this mode of reproduction. 
Drawings must be in dead black ink (BourcEors A1nf, Encre de 
Chine Liquide; Wr1Nsor and Newron, Liquid India Ink; HIGGINS, 
Waterproof Drawing Ink), and always in line and stipple only. Pale 
ink or a wash or tint make the use of the process impossible, unless the 
etching is supplemented by a second block in half-tone. Drawings should 
not be less than one half larger than the reproduction is to appear; prefer- 
ably they should be of double size, and for open diagrams or charts treble 
or even quadruple size may be better. This permits refinement of line 
and fine shading without excessive care in making the original. To see 
how a coarse drawing will look a concave lens 4 or 5°™ in diameter should 
be available. There are few observers who can draw at all, and none 
who draw well with a pencil, who cannot readily acquire the art of drawing 
with ink in a style suitable to be reproduced by copper or zinc etching. 
This gives freedom to put illustrations in the text where this is desirable, 
or to combine them into a plate if necessary. 
Examples:—26; pls. 1, 2 (a fine example of pure line); 32: pls. 10 
12 (almost pure stipple); 33: pl. 14 (line and stipple); 36: facing P- 188 
(map, letters and figures pasted on; red index lines and figures by second 
printing); 39: facing p. 102 (map, two blocks made from single drawing 
