LINE DRAWING: PRACTICAL

In Blocking-in observe Shape of the Background as much as the Object.

In the case of foreshortenings, the eye, unaided by this blocking out, is always apt to be led astray. And here the observation of the shape of the background against the object will be of great assistance. The appearance of the foreshortened object is so unlike what you know it to be as a solid thing, that much as it is as well to concentrate the attention on the background rather than on the form in this blocking-out process. And in fact, in blocking out any object, whether foreshortened or not, the shape of the background should be observed as carefully as any other shape. But in making the drawing proper, the forms must be observed in their inner relations. That is to say, the lines bounding one side of a form must be observed in relation to the lines bounding the other side; as the true expression of form, which is the object of drawing, depends on the true relationship of these boundaries. The drawing of the two sides should be carried on simultaneously, so that one may constantly compare them.

Boundaries a series of Overlappings.

The boundaries of forms with any complexity, such as the human figure, are not continuous lines. One form overlaps another, like the lines of a range of hills. And this overlapping should be sought for and carefully expressed, the outlines being made up of a series of overlappings.

Shading.

In Line Drawing shading should only be used to aid the expression of form. It is not advisable to aim at representing the true tone values.

94In direct light it will be observed that a solid object has some portion of its surface in light, while other portions, those turned away from the light, are in shadow. Shadows are also cast on the ground and surrounding objects, called cast shadows. The parts of an object reflecting the most direct light are called the high lights. If the object have a shiny surface these lights are clear and distinct; if a dull surface, soft and diffused. In the case of a very shiny surface, such as a glazed pot, the light may be reflected so completely that a picture of the source of light, usually a window, will be seen.

In the diagram on page 95 [Transcribers Note: Diagram V], let A represent the plan of a cone, B C the opening of a window, and D the eye of the spectator, and E F G the wall of a room. Light travels in straight lines from the window, strikes the surface of the cone, and is reflected to the eye, making the angle of incidence equal to the angle of reflection, the angle of incidence being that made by the light striking an object, and the angle of reflection that made by the light in leaving the surface.

It will be seen that the lines B1D, C2D are the limits of the direct rays of light that come to the eye from the cone, and that therefore between points 1 and 2 will be seen the highest light. If the cone have a perfect reflecting surface, such as a looking-glass has, this would be all the direct light that would be reflected from the cone to the eye. But assuming it to have what is called a dull surface, light would be reflected from other parts also, although not in so great a quantity. If what is called a dull surface is looked at under a microscope it will be found to be quite rough, 96i.e. made up of many facets which catch light at different angles.

Diagram V. PLAN OF CONE A, LIT BY WINDOW BC; POSITION OF EYE D. ILLUSTRATING PRINCIPLES OF LIGHT AND SHADE

Diagram V.

PLAN OF CONE A, LIT BY WINDOW BC; POSITION OF EYE D. ILLUSTRATING PRINCIPLES OF LIGHT AND SHADE

Lines B4, C3 represent the extreme limits of light that can be received by the cone, and therefore at points 3 and 4 the shadow will commence. The fact that light is reflected to the eye right up to the point 3 does not upset the theory that it can only be reflected from points where the angle of incidence can equal the angle of reflection, as it would seem to do, because the surface being rough presents facets at different angles, from some of which it can be reflected to the eye right up to point 3. The number of these facets that can so reflect is naturally greatest near the high lights, and gets gradually less as the surface turns more away; until the point is reached where the shadows begin, at which point the surface positively turns away from the light and the reflection of direct light ceases altogether. After point 3 there would be no light coming to the eye from the object, were it not that it receives reflected light. Now, the greatest amount of reflected light will come from the direction opposite to that of the direct light, as all objects in this direction are strongly lit. The surface of the wall between points E and H, being directly opposite the light, will give most reflection. And between points 5 and 6 this light will be reflected by the cone to the eye in its greatest intensity, since at these points the angles of incidence equal the angles of reflection. The other parts of the shadow will receive a certain amount of reflected light, lessening in amount on either side of these points. We have now rays of light coming to the eye from the cone between the extreme points 7 and 8. From 7 to 3 we have 97the light, including the half tones. Between 1 and 2 the high light. Between 3 and 8 the shadows, with the greatest amount of reflected light between 5 and 6.