fers to use this fitting in the drawing of work in which water pipe is to be drawn,

FIG. 52.

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

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.

W

HILE it must be clear to our readers that the ability to make a good, clear pencil 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 further and take up inking. Inking adds character to a drawing, and makes the work much clearer than pencil can. Another 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 square and triangles, etc.

Now if the drawing is inked, the whole surface can be gone over with a soft sponge rubber, which will not rub off 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 traced off onto the clean sheet. No doubt those who are pursuing this series have 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 experience of skilled draughtsmen. One suggestion would be, as far as possible, to complete the work at the top of the sheet first, then that next lower down, etc. This will save rubbing over finished parts of the drawing.

Another point is to see that the square

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 instruments 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 less use of. Common writing ink is not suitable 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 manner in which the inking instruments are filled with ink. The quill, which holds quite 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, as 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 experience 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, a good, heavy line is preferable, and if blue prints are to be taken from the drawing, night lines are apt to appear dim on the print, especially if over-exposed. Therefore, do

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 instru ment 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 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 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.