not make the mistake of getting the lines too fine. In Fig. 56 we have endeavored to show how the ruling pen should be held in drawing straight lines. It should be held as in No. 1, nearly straight, against the edge of triangle or tee square, and bearing away from it slightly, to give clearance between the triangle and the pen. If held as in No. 2, as beginners sometimes do hold it, that is, with the angle and drawing board, the result will be that when the triangle is drawn away after the line has been made, it will draw the ink with it, and make a wide blot on the paper, as in Fig. 57. The position of the pen in No. 3 is wrong also, for when held at such an angle the ink will not flow at all, or if it does, the line will be a very poor one. Do not bear down hard in making ink lines, for the instruments if properly ground and properly adjusted should allow the ink to flow freely enough to make good lines, under a light pressure from the hand. Very often bearing on will serve to prevent the instrument from making any line whatever, excepting the indentation into the paper, and moreover, in time it will wear the point. Drawing ink dries very quickly. eamphor being used in its make-up, and if care is not taken it will dry on the end of the pen and prevent the flow of ink. To start the ink it is a good plan to press the nib of the pen flatwise on the board, as in No. 2, Fig. 57, and unless too badly stopped, two or three attempts will usually be enough. A little moisture on the tip of the finger will also serve to start the ink. A piece of chamois skin or soft cloth should always be at hand for cleaning the ink out of the pens, and they should usually be cleaned before putting in new ink. It is best always to clean the pens after using them, for after the ink hardens it is much more difficult. It is also necessary to see that the point of the pen does not take up pieces of lint, etc., for the tiniest piece on the end of the pen will make sorry looking work. Of course it will be understood that inking is not done on a drawing as it is being In inking a drawing, it is very essential that all the curves, both large and small, shall be inked first. It is best to go through the entire drawing, putting in every curve, rather than to ink the curves of a portion of the drawing, then lay the bow pens and put in a few straight lines, etc. After putting in the curves, with the tee square, put in all the horizontal lines, then with the triangle put in all the vertical lines, after which oblique lines are drawn. This system enables the work to be done in much less time than would be the case if it was the oblique lines are drawn. This system enables the work to be done in much less time than would be the case if it was done hit-a-miss. After all the lines are in, with a common fine pen touch up the little points, the curves that are too small to be put in with instruments, etc. In drawing the curves do not make the mistake of carrying them around beyond No 6 No 7. the point where the straight lines should join them, as in No. 3 of Fig. 57, or fail to run the two lines together smoothly, as in No. 4. No. 5 shows them run together smoothly, as they should be. The reason, by the way, for putting in the curved lines of a drawing first, is that it is much easier to make straight lines meet a curve than to make a curve connect properly into two straight lines. In No. 6 of Fig. 57 shows two straight lines, the upper one being altogether too light and the lower one about right. making dotted lines do not make them too coarse or too fine, as shown in the two upper lines of No. 7, but of medium length, as in the lower line. We have not space for the regular exercises in this book, but those that are thinking of taking up inking cannot do better than practise on the inking of some of the more simple exercises which have previously been given. W CHAPTER XI HILE taking up the subject of inking, it will be well to is not a necessity in the making of good Shading is used to set off a drawing, and to make it clearer than can be done with the plain work such as we have used up to this point. It gives character to the drawing, and makes it more attractive. From the manner in which the shading appears, it can be told at once whether a certain part of the drawing represents a projection or a hole in the object illustrated. Thus in Fig. 58, the shading of No. 1 shows that it is a solid piece, a rectangular block for instance. Now, referring to No. 3 of the same sketch, Q, R, S, T represents a rectangular figure of the same size and shape as No. 1, but shaded in a different manner. This shading shows us at once that Q, R, S, T is a rectangular hole cut in the block M, N, O, P, the latter being of course shaded in the same manner as No. 1. Exactly in the same way, No. 2, shows by its shading a tee-shaped figure, and No. 4, by its different shading, shows a hole cut in the shape of a tee in the block U, V, W, X. Also, in Fig. 59, No. 2 shows the end of a solid cylinder, and No. 3, by the difference from No. 2 in shading represents a cylindrical hole bored into the end of the block R, S, T, U. Light and shade is naturally dependent upon the manner in which the rays of light fall upon an object, and in order to make the shading of drawings consistent and systematic, the rays of light must always be considered as coming from a given direction, and after determining upon the direction in which they are to come, it should not be changed. On this work, light may be assumed to come from the upper left hand corner of the drawing board, parallel with the surface of the board, and at an angle of 45 degrees with the horizontal and vertical lines of the drawing. These rays of light are represented by the arrowheads of Nos. 1 and 2 in Figs. 58 and 59. Any surface which these 45-degree lines strike is a light surface, and one which they do not strike is a dark surface. The line of intersection of two light surfaces is a light line, and not shaded, but the line of intersection of a light and a dark surface, or of two dark surfaces should be shaded. Lines in the drawing which are drawn at 45 degrees and parallel with the rays of light are never shaded. Referring again to No. 1, of Fig. 58, it will be seen that light strikes the lines A B and A C, which are therefore light lines, but because the object itself presents an obstacle to the further passage of light, the lines B D and C D are dark, and therefore shaded. In the same way we can account for the light and heavy lines in No. 2. In No. 2 it will be observed that the arrowhead passing through the corner G would strike the line H K at Y. It will be asked why H K is not shaded above Y, as the lines of light do not strike it. According to what we have said on the subject, this should follow, but it will be seen that a line partly heavy and partly light would not look well, and, therefore, for the sake of preserving the system, a line of this kind and in such location is made light. Another contradiction arises of a similar nature, in connection with Nos. 3 and 4. It would rightly be argued that owing to the wall or shell surrounding the hole, no light would strike the lines representing the rectangular hole, and therefore all four of those lines should be dark. method followed in Nos. 3 and 4. Comparing Nos. 1 and 3, it will be seen that lines shaded in the one are light in the other, also in the case of Nos. 3 and 4. In No. 1 of Fig. 59, the same difficulties or apparent contradictions arise that we have already mentioned. In such a case as this, in order to preserve the uniformity of the system, each branch must be considered entirely by itself, and then there will be no trouble. In this figure, the lines A O, BO, CO, and D O, also the four lines, E O, FO, GO and H O are drawn at 45 degrees. The first four are drawn parallel to the direction of the rays of light, and are therefore not shaded, but in the case of the latter four, although drawn at 45 degrees, they are not parallel to the rays of light, and should therefore be treated as any other lines would. In the case of the shading of circles, the reasoning is no different from that followed in the shading of straight lines. Those rays that strike the circle on a tangent determine the points at which the shading should begin. In shading a circle, draw in the light circle first, then with the same radius take a new center at an angle of 45 degrees from the first center, the distance between the two centers determining the width of the shade line at its widest point. In No. 2, the second center is taken above, and in No. 3 below the first center. In putting in the second circle, use the same size of line as in the first, and fill in the space between them. In Fig. 60 we give exercises in shading, which will serve to show how the principles which we have discussed above, are applied on the shading of plumbing drawings. In putting in the shade lines, they are usually drawn heavy at the outset, but it may possibly be easier for beginners to ink their drawings in the usual way, and then go over the lines to be shaded afterward, making them several times heavier than the light lines. If those who do not take up the inking care to do so they may shade their pencil drawings by using on the heavy lines a very soft pencil. In inking shaded drawings it is customary to put in the light horizontal lines first, then the heavy lines, and so with the vertical lines. This method will save the trouble of changing the adjustment on the pen so frequently, and will result in more even work. |