n metal, &c., for
the purpose of being subsequently printed on paper. The ancients are
well known to have excelled in engraving on precious stones; many
specimens have been preserved, which surpass anything of the kind
produced by the moderns. This art is frequently alluded to in the
Bible. Engraving on wood, according to some authors, was introduced
into Europe from China by Venetian merchants; it is certain the art
was practised in eastern and northern Italy as early as the thirteenth
century. The invention of copper-plate engraving has been ascribed to
a goldsmith of Florence, about the year 1460.

_Device_, that which is formed by design.

_Design_, a representation of a thing by an outline; a
sketch.

Describe Wood Engraving.

The subject is drawn on a block of box or pear-tree wood with a
black-lead pencil, or with a pen and Indian ink; the wood is then cut
away, so as to leave the lines which have been drawn, as raised parts.
The ink is next applied, and by pressing damp paper upon the block,
the impressions are obtained. Albert Durer, a celebrated painter of
Germany, brought the art of engraving on wood and metal, and taking
off impressions on paper, &c., to great perfection.

How is engraving on copper, steel, &c., performed?

This sort of engraving is performed with a sharp-pointed instrument
called a _graver_, by means of which figures, landscapes, &c., are
traced upon a flat surface of the metal: the lines are then filled
with ink or a similar composition, and the paper pressed on the plate.
When taken off, an exact copy of the plate is impressed upon its
surface.

[Illustration: COCHINEAL INSECTS AND PLANTS.]

What is Lithography?

A species of engraving on stone, from which impressions can be taken
much more expeditiously and economically than from metal. The process
depends upon the following principles:--First, the facility with which
calcareous stones imbibe water; second, the power of oily substances
to repel water. When drawings are executed upon the stone with crayons
composed of oily materials, and the surface of the stone is washed
over with water, the moisture is imbibed by the stone, but repelled
from the engraving; and when the ink, which also contains oily
substances, is applied, it adheres only to the drawing, and not to the
other portions of the stone. The block is then passed through a press,
and the impressions are taken off; as many as 70,000 perfect copies