33. General Directions for Drawing the Examination Plates. The examination plates are plknned to give as great a variety to the style of drawing as possible. The architect is called upon to use freehand drawing in two general ways; to make work ing drawings of ornament, either painted or carved, and to make, tor reference, sketches or notes, more or less elaborate, from orna ment already in existence, or from buildings either entire or in part, as well as from their landscape setting. This course will not include drawing of architecture and landscape.
In making a working drawing of ornament every shape and curve should be drawn to perfection, with clean, careful lines, in order that there shall be no opportunity for the craftsman who executes the work to interpret it differently from the designer's intention. Light and shade are used sparingly as the exact amount of relief is indicated by sections.
In making sketches or notes, while proportions must be accu rately studied, form may be suggested by a much freer quality of line. In a working drawing light and shade may be merely indi cated or may be carried to any degree of elaboration. The natural way of teaching this kind of drawing is to work from the objects themselves or from casts. This is not possible in a correspondence course, but all the principles of sketching may be very well taught by drawing from photographs of ornament, and this method has some decided advantages of its own a beginner. The light and shade in the photograph are fixed, while in sketching objects out of doors it changes constantly, and even indoors is subject to some fluctuation ; and then, in the photograph the object is more isolated from its surroundings and so is less confusing to perceive.
In order to train the sense of proportion as thoroughly as pos sible, the plates are to be executed on a much larger scale than the examples, but at no fixed scale. Plan each drawing to be as large as possible, where no dimensions are given, but do not allow any point in the drawing to approach nearer than one inch to the border line.
34. Varieties of Shading. In drawing in pen and ink, all effects of shadow are made by lines, and different values are ob tained by varying the width of lines, or of the spaces between the lines, or by both. .In any case the integrity of each line must be preserved and there can be very little crossing or touching of shade lines, as that causes a black spot in the tone unless lines cross each other systematically and produce cross hatching. With the pen cil, however, owing to its granular character one may produce a tone without any lines; a tone made up of lines which by touching or overlapping produce a soft, blended effect, in which the general direction of the strokes is still visible, or a tone made up of pure lines as in pen work. In general it does not matter so much, as in pen drawing, if lines touch or overlap. Indeed, the natural character of the pencil line leads to a treatment which 'includes both pure lines and inure or less blended effects.
35. Directions of Shade Lines. It is always a very impor tant matter to decide what direction shade lines shall take. While it is impossible to give rules for it, a good general principle is to make the direction of the lines follow the contours of the form. The easiest and simplest method is to make all the lines upright. This method is a very popular one with architects. The objec tions to it are monotony and a lack of expression, but it is certainly a very safe method and far preferable to one where desire for variety has been carried too far and lines lead the eye in a great number of different directions which contradict the general lines of the surface or form. A natural treatment is to adapt the direc tion of lines to the character of the surface represented; that is, to treat curved surfaces with curving lines and flat planes with straight lines, and in general, lines may very well follow either the contours or the surfaces of the form. In that way variety is obtained and the direction of the shading helps to express the char acter of the thing represented. This principle must, however, be modified when it leads to the introduction of violently opposing sets of lines. Abrupt transitions must be avoided and the change from one direction to another must be accomplished gradually.
Where a large surface is to receive a tone, the tone can best be made by a series of rather short lines side by side with succeed ing series juxtaposed. The lengths of the lines in each of theseries must vary considerably in order that the breaks in the lines may not occur in even rows, producing lines of white through the tone. (See Fig. 25.) The crossing of one system of parallel lines by another system is called cross hatching. This method probably originated in copperplate engraving, to which it is very well adapted, especially as a means of modifying and deepening tones. It also changes and breaks up the rather stringy texture produced by a succession of long parallel lines. It has now become somewhat obsolete as a general method for pen or pencil drawing, largely because the result looks labored, for it is always desirable to produce effects more simply and directly, that is, with one set of lines instead of two or more. If the tone made by one set of lines needs darkening, it is now more usual to go over the first tone with another set of lines in the same direction.
A great many drawings have been made with shade lines all in a diagonal direction, but this is open to serious objection and should be avoided. A diagonal line is always opposed to the prin ciple of gravitation, and tends to render objects unstable and give them the appearance'of tilting. It is often desirable to begin a tone with diagonal lines which, however, should gradually be made to swing into either an upright or horizontal direction.