Fig. 64. - Showing where Lead is Wanted in Bending (g, h), that point, for though it would not melt, the lead would become brittle and break in the bending. When water dropped upon the pipe assumes a spheroidal form, it is a proof that the lead is too hot. Why water assumes such a form when dropped upon metals very hot, red-hot, is that the " sphere of water does not come into contact1 with the hot metal, but rests on an elastic surface or cushion of

1 Prof. Dewar, in his juvenile lectures at the Royal Institution this last winter, on "Fire and Frost," "threw some molten lead out of a ladle with a bare wet hand, the steam formed upon the hand by the heat of the lead preventing actual contact between the metal and the skin." steam. As the metal cools, the heat is not sufficient to maintain this condition, and the water thus comes in contact with the metal, hisses, boils, and evaporates."

The pipe being properly heated, stride over it with your face towards the end (n, fig. 65) to be pulled up, and press your hand (with a felt or a thick cloth under it, to prevent the hand from being burnt) upon the pipe where it is to be bent, and get your mate to pull up the end of the pipe, humouring the bending part as much as possible to keep it in a circular form to prevent it from crippling. Lay the pipe down on one side quickly, and, with two or three sharp driving strokes of the dresser, jerk and dress the bulged part (k, fig. 65) of the piping from the side facing you, round towards the heel, l, of the bend. Turn the pipe over, while it is still hot, and dress

Fig. 65. - View of an unfinished Bend in a length of the bulged part of the opposite side round to the heel, in a similar way to that just described. By this means you will thicken the lead where it had been weakened in bending it, and you will at the same time be giving room for the dummy to work inside the pipe. Take the dummy (p, fig. 65) and put inside the pipe, n, and get your mate to knock up the neck part of the bend with the bulb of solder, O, on the end of the dummy, p, while you are dressing out the irregularities - dressing the lead ever towards the heel, l, to thicken the lead there. Do not attempt too much at a time, for to make a good bend, and to make it quickly, several such heats must be given it as just described. Watch the blows of the dummy, and see that they are rightly delivered, so that not a blow may be wasted.

10. A hand dummy, as illustrated in fig. 66, is a most useful tool for the plumber for many purposes, but in no piece of work is it more useful to him than in pipe-bending, when he can well reach the throttled pipe with it. The handle is generally made of cane, and the dummy, the bulb at the end, of solder. The long dummy, as shown at p, or Q, fig. 65, is wanted in various lengths, but a 5 ft. dummy is a very useful length. Some plumbers make their dummies with pieces of 5/8 in. iron rod, but the general plumber uses 1/2 in. or J in. gas-tubing, according to the length of the dummy.

Fig. 66. - Hand Dummy.

11. Some young plumbers, to show that they have mastered the art of pipe-bending, over-bend their pipes. Wherever a bend is wanted in a pipe, they make it as sharp as possible. Now no pipe should be bent at a greater angle than necessity requires, and great care should be taken to keep the bend rounding, for plumbing is not gas-fitting, and no square elbow bends are required. It has this great advantage over cast-iron pipe, that lead pipe, by the skilled plumber, can be bent on the spot exactly as it is wanted.

12. No bend is properly made in a lead pipe where the lead is in any part reduced in strength below its original substance.

13. It is the practice now with some plumbers in bending pipes to use what are called bobbins and followers, for opening out the pipes, to make them of full bore. The fnnnel-pipe is partly bent, and then a bobbin, as shown at b, fig. 67, is put into the pipe with one or two followers, which are made of box-wood, in various lengths, as shown in the illustration, fig. 67, at f f f. When the pipe is bent to the required angle the bobbins and followers are put into the pipe, and driven through it by the driving-rod, B; but it will be seen at once by the careful observer that unless this is done with great care, there will be danger of damaging the pipe by driving the follower, f, athwart into the heel of the bend, as shown by the arrow in the woodcut.

Fig. 67. - Section of a Bent Pipe, showing the evils of Bobbins (b) and Followers (f).

14. Driving a bobbin through a bent pipe insures a full bore through it; but the inpingement of the bobbin or follower upon an indentation in the pipe may often weaken the lead in places unnoticed by the plumber. All the tools a man wants to make a perfect bend in a lead soil-pipe or ventilating-pipe, as illustrated in fig. 68, is a dummy and a dresser or two, though a strip or two of lead of various widths - dependent upon the radius of the bend - is an advantage for removing tool-marks and planishing the pipe. Fig. 68 illustrates a double bend made in a 10 ft. length of

3 1/2 in. 8 lb. lead soil-pipe, made simply with a dummy and a dresser or two, with, of course, the slight assistance of an intelligent plumber.

15. It is not only important that soil-pipes and ventilating-pipes should not be contracted in the throat part of their bends, it is equally important that waste - pipes and service-pipes should be of full bore right throughout, and not throttled in their bends, as unfortunately is too often the case.

16. For bending lead pipes of a size too small for the hand dummy or long dummy to be of any service, a piece of bent gas-pipe, or iron bolts, as shown at A and B, fig. 69, will serve the plumber's need. The bolts are better when made of steel.

17. A skilful pipe-bender can generally manage to bend strong lead service-pipes by giving them an easy radius, without contracting them to any noticeable extent. To do this, heat the pipe where it is to be bent up to hissing-point when spat upon. Then lay the pipe down on its side, placing a thick piece of soft leather or felt, or two or three thicknesses of carpet, under one of the bulged sides of the bend, and then, with your old cap or ladle-felt placed upon the other side - the part facing you - to act as a buffer to break the sharpness of the blows, drive the bulged part of the side round to the heel of the bend. Turn the pipe over, and do the same to the other side.

18. Although the method of bending service-pipes is also very helpful in bending light lead pipes - as waste-pipes - the iron bolts must be resorted to, to work out the parts contracted in the bending; and this is readily done where the bend is near the end of a pipe;, and for this reason pipes have often to be cut, but it is better to cut a pipe to a shorter length to make the bend in it full bore rather than fix a long pipe with a restricted bend in it.

Fig. 68. - View of a Double Bend.

19. Lead funnel-pipes are also bent by filling them with sand; but in this method the substance of the lead at the heel - the back of the bend - gets much reduced, and there is no surplus or bulged parts for working round to thicken it again, as in a kink for dummying out (Art. 9).

Fig. 69. - View of Iron Bolts.