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gave in the preceding chapter is
ly is of value in making the drawing very clear and distinct. There is also another method of shading, which, however, is much more difficult of execution.
This style of shading we show in Figs. 62, 63 and 64, and in order to be able to use it to good effect, considerable experience and practice is necessary. It is used more for ornamental purposes than for practical purposes, but still, no book on drawing would be complete without some attention to it. It is seldom or never that a drawing of any extent would be shaded throughout in this manner, but our readers will find, if they do much in the way of drawing, that its use will often be a valuable aid in showing up apparatus of different kinds, portions of plain drawings that are desired to be brought out with great clearness, etc.
In the use of this shading, there are exact rules that are laid down as to the point which should be shaded heaviest, as well as lightest. It will be sufficient, however, for our purposes to make this instruction very brief and to the point.
The results seen in Nos. 1 and 2, of Fig. 62, are obtained by giving the greatest shade effect to the right hand side of the figure, the lightest point being about midway, and the left hand side being shaded somewhat, though not so heavily as the right hand side. These two figures represent solid cylindrical figures. No. 3, a hollow cylindrical figure is shaded in exactly an opposite manner, that is, with the heaviest shading at the left, medium shade effect at the right, but with the lightest point still near the center. No. 4, a horizontal solid cylinder, is shaded
heavy at the bottom, and medium at the top, while No. 5, a horizontal hollow cyl. inder is shaded in an opposite manner, as will readily be seen. Additional effect is gained by using the heavy shade lines as described in the preceding article.
In drawing these shade lines, the efcect of shade is gained entirely by the closeness of the lines together, the heavy shading being produced by drawing the lines closely together and the light shading by giving considerable space between the lines, additional effect being given by breaking the lines as appears on most of the figures. The skill in doing this work comes from the ability to vary the spaces between the lines in such a manner that the figure will appear cylindrical at all points, and nowhere flat, as it would if the spacing was not varied continually.
The greater the diameter of the cylin. drical figure, the greater should be the space between lines at the lightest point. The proper spacing of these lines is gained only from practice, it being a thing that cannot be reached from any exact instructions, or from measurement.
To those who are not interested in the inking of drawings, we would say that this shading can be done also with lead pencil. In Fig. 63, No. 1 shows ar elbow shaded. The curved lines are all struck from the one center, and should be put in first, and the straight lines connected with them afterward. In shading branches, as Nos. 2 ard 3, the lines of intersection should be drawn in first, and
the shade lines of the branch should end at those lines.
Fig. 64 shows the principle of line shading applied to a system of piping.
As we have already intimated, this work is more ornamental than otherwise, and a knowledge of its use will often be found handy. As our regular practice ex. ercise, we give this time, Fig. 65, an ele vation of the hot and cold water supply system for a two-flat house, and have shown the lines of pipe as single lines, the cold pipes being represented by solid lines, and the hot by dotted lines. This method is often preferable to using two parallel lines to show the pipe, as it is simpler to draw, takes less time, and often shows off the work fully as clearly. It will be understood that our illustrations being designed for reproduction as cuts in a paper, have to be drawn in black ink. Under ordinary conditions, different colored inks could be used to advantage, however. For instance, instead of dot. ting the hot water pipes, as we have to in this case to make our distinction from the cold water, the hot water pipe might be put in with solid red lines, with good effect. If desirable, a back air system might be put in with one color, while a different color was used on the drainage part of the work,
Sometimes, also. it is required to make a drawing in which part of the work is old work, and the rest new work. In this case, one color to show the old and an. other to show the new, makes good work, and is more readily distinguished.
concerning sectional draw boring pieces must be made by reversing
valuable aid in the clear rep posite angles, just as No. 2 shows. It resentation of many kinds of work, it will be observed that in drawing the secwill be worth our while to devote some space to their consideration. From a comparison of Nos. 1 and 2 in Fig. 66, we shall be able to see wherein the value of sectional drawings lies.
No. 1 represents a Fuller bibb, and the dotted lines represent the inside working parts.
No. 2 represents the same thing, but instead of drawing a plain view as in No. 1, the bibb is considered to be cut through along the center line, and the front balf
No. set aside. This allows a full view of the other half. A sectional view of the bibb is a view of this half section such as No. 2 gives, and it will be seen at once that the sectional view is far clearer than that shown by No. 1. To show that it is a sectional drawing, the part that is cut through is always sectioned or crosshatched. By this is meant the parallel lizes drawn close together, which desigaate the body of the bibb. These lines .nay be drawn with either the 45 deg. or 30 deg. triangle. Every point of any given piece should be sectioned in the
No 2. same way.. For instance, the inlet end of the bibb, which screws onto the body, is represented in the drawing by a section of metal above the center, and one below, both of which, being a part of the
FIG. 66. samé piece, should be sectioned by lines drawn in the same direction and at the tion the working parts have been drawn same angle. It is often the case that plain, and not in section. The idea is al. these sections are represented by differ ways to make any drawing show the obent colors instead of section lines, the dif ject it is made to represent with the ferent colors representing different pieces greatest possible amount of clearness, and of the article in question.
it will be found in this case that the bibb When section lines are used, and the is shown much more clearly by leaving different sectioned parts are in contact the working parts plain, instead of sec.