148 
B. DAYDON JACKSON-ADDKESS ! 
A much later instance is that of a plate by DiLLENius, also etched 
by the author; it is from his ‘Hortus Elthamensis,’ 1732, and 
represents the China aster, Aster chinensis. Another by Alpini 
(1592) of the plant now called Stcehelina arborescens is shown to 
display the art of producing relief in the printing, giving much the 
same effect as the modern method known as retroussage , the ink 
being made to overflow in some slight degree over the lines after 
the ground has been cleaned off. Etchers frequently use the 
needle to scratch lines on the metal, which gives a more delicate 
result than by biting in, hut in this example we have an entire 
design in dry-point by Dr. John Hill, who constantly employed 
this method. The needle thus used creates a burr on the metal, 
just sufficient to hold a small amount of ink, hut in old times, 
before plates were steeled, the act of cleaning off rapidly wore 
down the burr, hence you can perceive the lines becoming indistinct 
on the plate. 
The difficulty of properly biting and gradating the drawing led 
to the employment of trained engravers : here is a beautiful 
instance of such work in Vaillant’s folio on the plants about Paris, 
from a drawing by Aubriet, 1727 (PL II, fig. 4); the next is bolder, 
by Ehret, of a Piper in Linnaeus’s ‘Hortus Cliffortianus’ (1737). 
This, a Mentha (PI. Ill, fig. 1), in Sole’s well-known ‘ Menthae 
Britannicae,’ shows an attempt to compete with colour by expressing 
as much as possible in black and white. In passing I may remark 
that when plates are intended to be finished by colouring, little 
more than an outline is printed. 
Other methods have been tried: a softer style is attained as 
in the slide now shown, a Crinum , in mezzotint, employed by 
Professor John Martyn ; in this process the surface is impressed 
by a special tool, which creates the dark velvety ground which has 
then to be scraped and burnished up to the lights. 
Eor a long period copper-plate printing had ousted woodcuts as 
methods of botanic illustration, but a new period set in with 
Thomas Bewick. This celebrated engraver on wood saw the true 
way to use wood, not by competing with copper, and pretending to 
imitate the single easy incision of the graver by a tedious operation 
in wood, but by transferring the war into the enemies’ country, so 
to speak. He was the first to employ the white line and the flat 
black; and as the sample shown, henbane, in Thornton’s ‘ Herbal ’ 
(1810), does but scant justice to Bewick’s merits, I show his cut 
of the grasshopper warbler, to illustrate his use of the two methods 
just mentioned. The Japanese have long employed the flat black, 
as may be seen in this slide of Podocarpus macrophylla , taken 
