where; therefore you must put in other lines, or little
scratches and dots, _between_ the lines in the paler parts; and where
there are any very conspicuous dark lines, scratch them out lightly with
the penknife, for the eye must not be attracted by any line in
particular. The more carefully and delicately you fill in the little
gaps and holes the better; you will get on faster by doing two or three
squares perfectly than a great many badly. As the tint gets closer and
begins to look even, work with very little ink in your pen, so as hardly
to make any mark on the paper; and at last, where it is too dark, use
the edge of your penknife very lightly, and for some time, to wear it
softly into an even tone. You will find that the greatest difficulty
consists in getting evenness: one bit will always look darker than
another bit of your square; or there will be a granulated and sandy look
over the whole. When you find your paper quite rough and in a mess,
give it up and begin another square, but do not rest satisfied till you
have done your best with every square. The tint at last ought at least
to be as close and even as that in _b_, Fig. 1. You will find, however,
that it is very difficult to get a pale tint; because, naturally, the
ink lines necessary to produce a close tint at all, blacken the paper
more than you want. You must get over this difficulty not so much by
leaving the lines wide apart as by trying to draw them excessively fine,
lightly and swiftly; being very cautious in filling in; and, at last,
passing the penknife over the whole. By keeping several squares in
progress at one time, and reserving your pen for the light one just when
the ink is nearly exhausted, you may get on better. The paper ought, at
last, to look lightly and evenly toned all over, with no lines
distinctly visible.

EXERCISE II.

10. As this exercise in shading is very tiresome, it will be well to
vary it by proceeding with another at the same time. The power of
shading rightly depends mainly on lightness of hand and keenness of
sight; but there are other qualities required in drawing, dependent not
merely on lightness, but steadiness of hand; and the eye, to be perfect
in its power, must be made accurate as well as keen, and not only see
shrewdly, but measure justly.

11. Possess yourself therefore of any cheap work on botany containing
_outline_ plates of leaves and flowers, it does not matter whether bad
or good: Baxter's British Fl