easy
matter, as the design is equally visible on both sides of the
tracing-paper. Gelatine in sheets, however, offers still greater
advantages when a design is to be reversed. Place the gelatine on the
design, and, as it is easily scratched, make your tracing with a very
fine-pointed and sharp needle, occasionally slipping a piece of black
paper underneath the gelatine to assure yourself that you have omitted
nothing. The point, in scratching the gelatine, raises a bur, and this
must be removed gently with a paper stump, or with the scraper, after
which operation the tracing is rubbed in with powdered sanguine. Having
now thoroughly cleaned the sheet, so that no powder is left anywhere
but in the furrows, we turn the sheet over and lay it down on the plate,
and finally rub it on its back in all directions, for which purpose we
use the burnisher dipped in oil. The design, reversed, will be found
traced on the varnish in extremely fine lines.

24. =Use of the Mirror.=--The tracing finished, place a mirror before
your plate on the table, and as close by as possible; between the plate
and the mirror fix the design to be reproduced, and then draw the
reflected image. For the sake of greater convenience, take your position
at right angles to the window instead of facing it, so that the light
passing through the transparent screen on your left falls on the mirror
and the design, as well as on your work. When drawing on the copper from
nature, if the design is to be reversed, you must place yourself with
your back to the object to be drawn, and so that you can easily see it
in a small mirror set up before your plate. This is the way Meryon
proceeded: standing, and holding in the same hand his plate and a little
mirror, which he always carried in his pocket, he guided his point with
the most absolute surety, without any further support.

25. =Precautions to be observed while Drawing.=--Before you begin to
draw you must trace the margin of your design, for the guidance of the
printer. To protect your plate, it will be necessary to cover it with
very soft paper; the pressure of the hand does no harm, provided you
avoid rubbing the varnish. If you should happen to damage it, you must
close up the brilliant little dots which you will observe, by touching
them up, very lightly and with a very fine brush, with stopping-out
varnish.

26. =Directions for Drawing with the Needle.=--I might now let you copy
some very simple etching; b