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fers to use this fitting in the drawing of work in which water pipe is to be drawn,
branch taken off the main back air where it offsets, comes out of the tee straight toward us, and then bends off at an angle of 45 deg., then comes out straight toward us again, and then runs horizontally. The bends used on this branch are in such a position that their true shape cannot be seen. If the beginner has difficulty at any time in seeing how different fittings appear when placed in certain positions, let him take the fittings themselves and place them before him in such positions as are required. In doing this, however, he must remember to draw whatever object he has before him, with the element of perspective entirely eliminated. We have referred to this before, but a cautionary word at this point will not be out of place. It will be noticed that all the fittings of Fig. 53, whether wrought iron or cast iron, are drawn with their ends square across, and not curved as they would usually appear in perspective. Occasionally a part of the work will have to be shown in such a way that a certain amount of perspective will have to be used, but for one unpracticed in its execution, it is a difficult matter to make such work look well, and errors on such work are very likely to destroy the appearance of an otherwise excellent drawing. We are ready now, we believe, to take up complete elevations of different work, including both drainage and supply, and this we shall do in the next chapter.
Sketch Showing Errors Likely to be Made. but in the case of wrought iron back air work, is inclined to use the plain fitting, as shown in Fig. 53, in which is represented back airing, including the main and the several branches. It will be noticed that fittings are shown in several different positions. For instance, the
Ruling Pere de
readers that the ability to much of the soiling of drawings is due
drawing is the chief point to be gained in pursuing a task of this kind, the ability to ink the drawings is also very desirable. We presume that many of those interested will care only for the pencil work, but others on the contrary will be anxious to go
Nol. further and take up inking. Inking adds character to a drawing, and makes the work much clearer than pencil can. An
Triangle, other point is this—if the drawing is of any extent, by the time the pencilling has been completed, even though a hard pencil has been used on the work, the sheet has become much soiled by constant rubbing over it of the hands, sleeves, the
NO2. square and triangles, etc. Now if the drawing is inked, the whole
Per surface can be gone over with a soft sponge rubber, which will not rub of the Inked lines, and the sheet made perfectly clean, or better still, a piece of transparent paper, such as thin bond paper, can be laid over the original pencil drawing and
Ruling traced off onto the clean sheet. No doubt those who are pursuing this series have No 3.
Peri long before this discovered that it is almost impossible to keep the sheet clean, and ofttimes the smut has made what would otherwise be a good piece of work, look rather dubious. This is to be expected, and is more or less the experi. ence of skilled draughtsmen. One sug. gestion would be, as far as possible, to
FIG. 56 complete the work at the top of the sheet first, then that next lower down, etc. This will savę rubbing over inished parts of 54 we show illustrations of the different the drawing.
drawing instruments which are necessary Another point is to see that the square for inking. No. 1 shows a straight line
ruling pen. It is used in drawing straight lines and is handled in the same way that a pencil is used, that is, by guiding it against the side of a triangle or tee
Square. No. 2 is called a bow pen, and is used in making small and medium sized circles. No. 3 is an attachment used in inking large circles. As shown, it is made with a joint and is designed to slip into the large compasses shown in our first chapter, taking the place of the pen cil attachment. Each of these three in. struments is usually to be found in the ordinary set of drawing instruments,
The bow pen and ruling pen are used constantly, and are absolutely necessary, while the attachment (No. 3) is made lege use of. Common writing ink is not suit. able for drawing purposes, an India ink being necessary. The ink usually comes in such a bottle as shown in No. 1 in Fig. 55. It will be observed that the stopper to the bottle is provided with a quill, which dips down into the ink. No. 2 in Fig. 55 will serve to illustrate the man. ner in which the inking Instruments are Alled with ink. The quill, which holds quito an amount of the ink, is touched lightly to the instrument, between the two nibs, and the ink at once flows from the quill and supplies the instrument, 28 the illustration shows.
It is best not to fill the instrument too full, usually not more than half as full as No. 2 indicates, for it is liable to flow too rapidly from the pen, and cause bad work. It will be readily understood that the size of the line is regulated by the little thumbscrew with which each instrument is supplied. By screwing the nibs close together a fine line is made, and a coarse one by releasing them. By the way, to those who have never had any experi. ence in inking, a word of advice as to the making of lines will be of benefit. The beginner, nine times out of ten, endeavors to make his lines as fine as possible. This the experienced draughtsman does not do. In the first place, the instruments do not work as well on fine lines. Then again, the drawing is not so clear, and in erasing, the fine lies are more liable to be partly rubbed out. If an illustration is to be made from the drawing, & good, heavy line is preferable, and if blue prints are to be taken from the drawing, right lines are apt to appear dim on the print, especially if over-exposed. Therefore, do
laid out. The drawing is laid out just in pencil, and then the pencil lines inked, or the work traced on transparent paper, as we have already stated.
not make the mistake of getting the lines too fl.pe.
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. 1l 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 hear 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 pres. sure 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. camphor 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 ren 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 essen- the point where the straight lines should tial that all the curves, both large and join them, as in No. 3 of Fig. 57, or fail small, shall be inked first. It is best to run the two lines together smoothly, as to go through the entire drawing, put in No. 4. No. 5 shows them run together ting in every curve, rather than to ink smoothly, as they should be. the curves of a portion of the drawing, The reason, by the way, for putting in then lay the bow pens and put in a few the curved lines of a drawing irst, is straight lines, etc. After putting in the that it is much easier to make straight curves, with the tee square, put in all lines meet a curve than to make a curve the horizontal lines, then with the tri- connect properly into two straight lines. angle put in all the vertical lines, after No. 6 of Fig. 57 shows two straight which oblique lines are drawn. This sys- lines, the upper one being altogether too tem enables the work to be done in much light and the lower one about right. In less time than would be the case if it was making dotted lines do not make them the oblique lines are drawn. This system too coarse or too fine, as shown in the enables the work to be done in much less two upper lines of No. 7, but of medium time than would be the case if it was length, as in the lower line. done hit-a-miss. After all the lines are We have not space for the regular exin, with a common fine pen touch up the ercises in this book, but those that are little points, the curves that are too thinking of taking up inking cannot do small to be put in with instruments, etc. better than practise on the inking of In drawing the curves do not make the some of the more simple exercises which mistake of carrying them around beyond have previously been given.