lead it over the
square as fast as possible, with such attention to your limit as you are
able to give. The use of the exercise is, indeed, to enable you finally
to strike the color up to the limit with perfect accuracy; but the first
thing is to get it even,--the power of rightly striking the edge comes
only by time and practice: even the greatest artists rarely can do this
quite perfectly.

27. When you have done one square, proceed to do another which does not
communicate with it. When you have thus done all the alternate squares,
as on a chess-board, turn the pasteboard upside down, begin again with
the first, and put another coat over it, and so on over all the others.
The use of turning the paper upside down is to neutralize the increase
of darkness towards the bottom of the squares, which would otherwise
take place from the ponding of the color.

28. Be resolved to use blotting-paper, or a piece of rag, instead of
your lips, to dry the brush. The habit of doing so, once acquired, will
save you from much partial poisoning. Take care, however, always to draw
the brush from root to point, otherwise you will spoil it. You may even
wipe it as you would a pen when you want it very dry, without doing
harm, provided you do not crush it upwards. Get a good brush at first,
and cherish it; it will serve you longer and better than many bad ones.

29. When you have done the squares all over again, do them a third time,
always trying to keep your edges as neat as possible. When your color is
exhausted, mix more in the same proportions, two teaspoonfuls to as much
as you can grind with a drop; and when you have done the alternate
squares three times over, as the paper will be getting very damp, and
dry more slowly, begin on the white squares, and bring them up to the
same tint in the same way. The amount of jagged dark line which then
will mark the limits of the squares will be the exact measure of your
unskillfulness.

30. As soon as you tire of squares draw circles (with compasses); and
then draw straight lines irregularly across circles, and fill up the
spaces so produced between the straight line and the circumference; and
then draw any simple shapes of leaves, according to the exercise No.
II., and fill up those, until you can lay on color quite evenly in any
shape you want.

31. You will find in the course of this practice, as you cannot always
put exactly the same quantity of water to the color, that the darker the