branch should run out straight for a little distance and not start to curve at once from the main part of the fitting. In Fig. 37 we give two exercises in drawing which combine the several fittings shown in the two preceding figures. We would advise some little practice on the work shown in Figs. 35 and 36, and then practice on the work of Fig, 37,

In No. 1 the vent from the upper vented T-Y is shown offset into the main vent through a vent T turned slightly from its straight position. In laying out these two exercises, first put in the two main lines of pipes without hubs, the line of vent being shown nearly its diameter away from the other pipe. The side elevation will receive attention next.

N the preceding chapter we showed front and side elevations of the plumbing of a residence, and noted the fact that the side elevation was by far the clearer, consequently the more valuable of the two. These views were drawn on the

same scale as the floor plans, and as may have been evident to our readers, this scale was so small that it was more or less difficult to trace out the work, and that the smaller details could not be clearly shown. In Fig. 38 we show the principal part of the side elevation men

tioned, drawn on a scale of double size. It will be noticed how much more clearly the work appears. The wiped joints for instance, can be more clearly shown, the beads on the soil pipe hubs, etc. All these minor points go to giving character to a drawing and it is always well to show them.

We would therefore strongly advise our readers against making their draw. ings on too small a scale. Fig. 38, while double the scale used on the elevations shown in Chapter 6, is too small, and we should have made it larger, but for the necessity of economizing space. The smaller the scale on which a drawing is made, the more difficult, the more puttering the work will be, and it has been the experience of the writer that beginners often discourage their own efforts by drawing their work too small. Another point in connection with Fig. 38, to which we wish to call attention, is the manner in which the main line of back air for the bathroom stack is shown. In Fig. 34 of the previous article, it is shown directly in line with, and in front of the main stack, and this is of course the true position for it in the view in question.

Instead of following the absolutely right way of showing this line of pipe in Fig. 38 we have shown it at the side of the main stack. A comparison of the two views will show at once that the method followed in Fig. 38 gives a better idea of the way in which the work is done, than Fig. 34. This is particularly true concerning the connection of the main back air into the stack, above the highest and below the lowest fixtures.

In a great many cases, probably a large majority of them, it could make no practical difference whether the relative positions of the stack and main back air were as they are shown in Fig. 34 or as shown in Fig. 38. When this is the case, it will often be found of advantage to draw certain parts of the work as if seen in a different view than the rest. As a general thing, an elevation is usually given simply to show the general layout of the work, the way in which the fixtures are to be connected, etc., and for the location of fixtures the floor plans

are made use of. Therefore, many times it is best to show such a view of certain

Fig. 39-A Practice Sketch

parts of the work, as will be of the greatest assistance in giving a clear idea of the method of putting in the work.

In Figs. 39, 40 and 41, we give three exercises, which the student will do well to practice on faithfully. They are somewhat more difficult than those which have preceded them, though not too difficult. We would advise going over the work several times if necessary to get results that will be satisfactory, carefully comparing the work with that which we give, and noting where improvements can be made.

It will be noticed on each of these exercises that there are a number of dots. These dots represent the centers for the different curves, that is, the points on which the instrument must be placed to draw the curves correctly. We have done this for the reason that the beginner in drawing, often has difficulty in deciding how large a radius he must take for striking a given curve.

Wherever a pipe curves, both the inside and outside curves are struck from the same centre. This must be so of course, in order that the bend in the pipe may be of the same diameter at every point. The further off the center is taken, or in other words, the greater the radius, the greater the sweep the curve will have. Thus in Fig. 39, it will be noticed that a branch enters the vertical line of pipe just below the entrance of the waste from the sink, and that in doing so quite a wide sweep is made, the center for which is nearly an inch away.

This we should draw in the following manner: Put in first the Y branch, which will give us the direction the curve has got to take. Next draw in the lines representing the straight run of pipe just under the floor. Then connect this straight section with the Y by means of the curve. After this has been done, draw in the hubs, erasing such of the lines as are not needed. In drawing the straight section of pipe beneath the floor, do not try to stop the lines at the exact point where the curves will meet them, but put them in indefinite length, and erase whatever runs by, after putting in the curves. Now, in laying out these drawings, if they are to be made on a

special scale, of course it will be necessary to work according to such scale,

Fig. 40-Another Practice Drawing.

but if the drawing is simply to show the general manner in which the work is to be installed, as would more often be the case in making plumbing drawings, then we need not be so careful in making the layout. We will suppose in the case of Figs. 39, 40 and 41, that no scale is required. Decide first on which side of the fixture the main waste and vent lines are to be run, then draw them without hubs, and draw the fixture in its position. Very often it is best as in the case of the sink in Fig. 39, to show the waste at the further end of the sink, as it can readily be seen that it would be close work to show it properly at the other end.

After having drawn the waste for the sink to the floor, draw in a general way the horizontal section of waste under the floor, with sufficient pitch, and from the course of this pipe it can be seen where the Y branch will have to be located. Then draw the Y branch beneath, and the branch line of pipe running into it, as explained above.

Now as to putting in the offset, it will probably be easier to draw in the main line into which the vertical branches, and come up with the bend, before putting in the offset. This method would usually be better, though in the present instance it does not matter particularly.

It will be noticed that in these exercises we have shown both sink and lavatory in two positions, one in which it is seen from the front, and the other from the end. This we do in order that the student may become accustomed to show

ing the work in whichever way it may be necessary. In the case of Fig. 41 we show an oval bowl. A side view of it, however, would not be materially different from the common round bowl.

In Fig. 40 it will be noticed that the

FIG.41.

lavatory appears to set too close to the ceiling, and that the vertical lines of pipe are broken. It often happens that in order to economize space, fixtures shown in illustrations appear too close to the ceiling. Many times this is almost unavoidable if the work is to be shown on a good fair scale, and often in such cases, the pipes are broken off, to show that the full length or height does not appear.