work may be obtained
at one and the same biting. As it is necessary in this sort of engraving
to retouch the heavy lines with the burin, we can understand that in the
way shown the work of the instrument named may be facilitated.

21. =Temperature of the Room.=--In summer the temperature softens the
varnish, and the needle works pliantly and easily; in winter the cold
hardens the varnish, so that it is apt to scale off under the point,
especially at the crossing of the lines. It is advisable, therefore, to
have your room well heated, or to supply yourself with two cast-metal
plates or two lithographic stones, or even two bricks, if you please,
which must be warmed and placed under your plate alternately, so as to
keep it at a soft and uniform temperature. Practice has shown that work
done at the right temperature is softer than that executed when the
varnish is too cold, even if it is not sufficiently so to scale off.

22. =The Tracing.=--According to the kind of work to be done, we shall
either draw directly on the plate, or, in the case of a drawing which is
to be copied of its own size, we shall make use of a tracing. Many
engravers emancipate themselves from the tracing, and accustom
themselves to reversing the original while they copy it. The manner of
using a tracing is well known. We shall need tracing-paper, paper rubbed
with sanguine on one side, and a pencil. The tracing is made on the
tracing-paper, and this is afterwards placed on the prepared plate;
between the tracing and the plate we introduce the paper rubbed with
sanguine; then, with a very fine lead-pencil, or with a somewhat blunt
needle, we go carefully over the lines of the design, which, under the
gentle pressure of the tool, is thus transferred in red to the black
ground. It is unnecessary to use much pressure, as otherwise your
tracing will be obscured by the sanguine and you will find neither
precision nor delicacy in it. Furthermore, you run the risk of injuring
the ground. The tracing is used simply to indicate the places where the
lines are to be, and it must be left to the needle to define them.

23. =Reversing the Design.=--Whenever your task is the interpretation of
an object of fixed aspect, such as a monument, or some well-known scene,
or human beings in a given attitude, you will be obliged to reverse the
drawing on your plate, as otherwise it will appear reversed in the
proof. You must, therefore, reverse your tracing, which is a very