This section is from the "The elements of drawing & the elements of perspective" book, by J. M. Dent & Sons. Also see Amazon: The Elements Of Drawing & The Elements Of Perspective.
By looking at any common woodcuts, in the cheap publications of the day, you may see how gradation is given to the sky by leaving the lines farther and farther apart; but you must make your lines as fine as you can, as well as far apart, towards the light; and do not try to make them long or straight, but let them cross irregularly in any directions easy to your hand, depending on nothing but their gradation for your effect. On this point of direction of lines, however, I shall have to tell you more presently; in the meantime, do not trouble yourself about it.
As soon as you find you can gradate tolerably with the pen, take an H. or HH. pencil, using its point to produce shade, from the darkest possible to the palest, in exactly the same manner as the pen, lightening, however, now with India-rubber instead of the penknife. You will find that all pale tints of shade are thus easily producible with great precision and tenderness, but that you cannot get the same dark power as with the pen and ink, and that the surface of the shade is apt to become glossy and metallic, or dirty-looking', or sandy. Persevere, however, in trying to bring it to evenness with the fine point, removing any single speck or line that may be too black, with the point of the knife: you must not scratch the whole with the knife as you do the ink. If you find the texture very speckled-looking, lighten it all over with India-rubber, and recover it again with sharp, and excessively fine touches of the pencil point, bringing the parts that are too pale to perfect evenness with the darker spots.
You cannot use the point too delicately or cunningly in doing this; work with it as if you were drawing the down on a butterfly's wing.At this stage of your progress, if not before, you may be assured that some clever friend will come in, and hold up his hands in mocking amazement, and ask you who could set you to that niggling; and if you persevere in it, you will have to sustain considerable persecution from your artistical acquaintances generally, who will tell you that all good drawing depends on boldness. But never mind them. You do not hear them tell a child, beginning music, to lay its little hand with a crash among the keys, in imitation of the great masters: yet they might, as reasonably as they may tell you to be bold in the present state of your knowledge. Bold, in the sense of being undaunted, yes; but bold in the sense of being careless, confident, or exhibitory, - no, - no, and a thousand times no; for, even if you were not a beginner, it would be bad advice that made you bold.
Mischief may easily be done quickly, but good and beautiful work is generally done slowly; you will find no boldness in the way a flower or a bird's wing is painted; and if Nature is not bold at her work, do you think you ought to be at yours? So never mind what people say, but work with your pencil point very patiently; and if you can trust me in anything, trust me when I tell you, that though there are all kinds and ways of art, - large work for large places, small work for narrow places, slow work for people who can wait, and quick work for people who cannot, - there is one quality, and, I think, only one, in which all great and good art agrees; - it is all delicate art. Coarse art is always bad art. You cannot understand this at present, because you do not know yet how much tender thought, and subtle care, the great painters put into touches that at first look coarse; but, believe me, it is true, and you will find it is so in due time.
You will be perhaps also troubled, in these first essays at pencil drawing, by noticing that more •delicate gradations are got in an instant by a chance touch of the India-rubber, than by an hour's labour with the point; and you may wonder why I tell you to produce tints so painfully, which might, it appears, be obtained with ease. But there are two reasons: the first, that when you come to draw forms, you must be able to gradate with absolute precision, in whatever place and direction you wish; not in any wise vaguely, as the India-rubber does it: and, secondly, that all natural shadows are more or less mingled with gleams of light. In the darkness of ground there is the light of the little pebbles or dust; in the darkness of foliage, the glitter of the leaves; in the darkness of flesh, transparency; in that of a stone, granulation: in every case there is some mingling of light, which cannot be represented by the leaden tone which you get by rubbing, or by an instrument known to artists as the stump. When you can manage the point properly, you will indeed be able to do much also with this instrument, or with your fingers; but then you will have to retouch the flat tints afterwards, so as to put life and light into them, and that can only be done with the point. Labour on, therefore, courageously, with that only.
When you can manage to tint and gradate tenderly with the pencil point, get a good large alphabet, and try to tint the letters into shape with the pencil point. Do not outline them first, but measure their height and extreme breadth with the compasses, as a b, a c, Fig. 3., and then scratch in their shapes gradually; the letter A, enclosed within the lines, being in what Turner would have called a state of forwardness. Then, when you are satisfied with the shape of the letter, draw pen and ink lines firmly round the tint, as at d, and remove any touches outside the limit, first with the India-rubber, and then with the penknife, so that all may look clear and right.