or Points.=--You may use a single needle, or you may use
several of different degrees of sharpness, even down to sewing-needles,
as you will see later on; but your work on the plate will always look
uniform, without distance and without relief. The modelling and coloring
of the design must be left to the acid.

The point must be held on the plate as perpendicularly as possible, as
the purity of the line depends on the angle of incidence which the point
makes with the copper; furthermore, it must be possible to direct it
freely and easily in all directions, and it is, therefore, necessary
that the needle should not be too sharp. To make sure of this, draw a
number of eights on the margin of your plate, or simply an oblique line
from below upwards in the direction of the needle. If it does not glide
along easily, if it attacks the copper and catches in it, you must
regrind it.

This is important, as in principle the function of the needle is to
trace the design by removing the varnish from the copper, while it must
avoid scratching it. By scratching the metal we encroach on the domain
of the acid, and inequality of work is the result, since the acid acts
more vigorously on those parts which have been scratched than on those
which have simply been laid bare. We must feel the copper under the
point, without, however, penetrating into it.

The opposite effect is produced if we operate too timidly. In this case
we do not reach the copper. We remove the blackened surface, and it
seems as if we had also removed the varnish, since we see the copper
shining through it. But we shall find later, from the fact that the acid
does not bite, that we did not bear heavily enough on the needle.

At first there is a tendency to proceed as in drawing on paper, giving
greater lightness to the touch of the point in the distances, and
bearing on it more vigorously in the foregrounds. But this is useless.

There are certain artists, nevertheless, who prefer to attack the copper
with cutting points in the finer as well as in the more vigorous parts
of their work, and to bite in with strong acid; others, again, dig
resolutely into the copper wherever they desire to produce a powerful
tone. Abraham Bosse, in applying etching to line-engraving, advises his
readers to cut the copper slightly in the lines which are to appear
fine, and to dig vigorously into the plate for those lines which are to
be very heavy, so that delicate as well as strong