To make the joint, open the end of the under and outer pipes by driving a mandril (or a gradation of sizes) into it for a depth of about 7 in., taking care to keep the mandril true all the while; and to prevent one part of the socket stretching more than another, well heat the pipe first. Round up the end of the inner pipe upon a mandril. A little grease rubbed over the mandril will enable it the better to be withdrawn after it has done its work; but where india-rubber is to be fixed between the pipes, the grease - which acts injuriously upon india-rubber - should be carefully removed from the pipes again. An india-rubber ring should be drawn over the end of the inner pipe, and the outer pipe opened just enough to allow the pipe and ring to enter, so that the end of the inner pipe, when put together, stands about an inch above the shoulder of the socket of the outer pipe. A sliding cap should be fixed on the top, as shown in fig. 144, to keep dirt, etc., out of the socket.

9. Where the waste-pipe from a tier of slop-sinks, or from a tier of wash-up and slop-sinks combined, or from a tier of general draw-off sinks, would be subject to expansion and contraction from hot and cold water discharges, and the pipe could not be fixed outside, instead of fixing the pipe of lead, inside the house it would be better to fix coated cast-iron pipe with india-rubber expansion joints, as shown in fig. 146; or the pipe could be of wrought iron - galvanized inside and out - with screwed joints.

10. Traps should be fixed under the slop-sinks as circumstances require, a larger size being fixed in hospitals; in fact in such places the traps, waste-pipes, and ventilation-pipes should be of the sizes as used for the water-closets. (Art. 7.)

11. No slop-sink or slop-closet should be fixed without a means of flushing it out. Flushing-cisterns, similar to those described for flushing out closets (Chap. XXXII., Arts. 3 and 4), should be fixed where possible, as shown at v and w, fig. 143.

12. It seems a waste of words to say that a sink made of a non-absorbent material is more wholesome than one made of an absorbent kind, such as wood or sandstone; and yet the latter kinds are often fixed in places where there would have been no difficulty in fixing sinks of fireclay, stoneware, earthenware, or copper, supposing the man who provided the sandstone sink had some objection to lead-lined sinks.

13. For washing up glass or china, wood sinks lined with tinned copper are preferable to either earthenware or fire-clay - where money and tempers are valued; for whilst there would be no elasticity in the latter (fire-clay), there would be just enough in the former (copper sink) to prevent many breakages of glass, china, and temper.

14. Round about the top of a sink there should be no opening, crevice, or place where filth could fall into, and by accumulating become offensive.

15. The bottoms of sinks should fall towards their outlets, and the outlets or apertures ought always to be large enough to receive gratings, or plugs-and-washers, which should have a water-way through them equal in area to fully charge the bore of the trap and waste-pipe to be fixed to them, as shown at a, fig. 145. (Chap. XXIV., Art. 7.)

The brass cobweb-grating, which was introduced and named by me many years ago, whether fitted to a brass rim or not, whether soldered over the mouth of the trap or fitted to the washer of a brass plug-and-washer, allows a sink to be emptied so much quicker than a round-hole grating, that one wonders why this kind of screener has not become universal; but its use is becoming more extensive every year.

16. All sinks which could have their apertures - their outlets - sealed up with fitted plugs should have overflow-pipes fixed to them; and this overflow-pipe, where it could not be carried out to the open air, should be connected to the sink in such a way that it could readily be flushed out and cleaned. (Chap. XXXV., Art. 4)

17. For pantry sinks, a 2 in. brass plug-and-washer, a 1 1/4 in. anti-D-trap, as fig. 89, and 1 1/2 in. lead waste-pipe discharging under the grating of an aerial disconnecting-trap fixed outside the house, make a wholesome arrangement. But in all cases, whether this kind of trap or a round-pipe trap be fixed, where the discharging end of the waste-pipe is more than four or five feet below the trap, it is necessary that the trap or waste-pipe should be vented, to prevent syphonage.

Fig. 145.

18. A 2 in. waste-pipe is quite large enough to take the branches of two or three sinks fixed on the several floors of a four-storied building. As previously explained, where hot water is laid on to a tier of sinks, and the waste-pipe is of lead, the pipe should be fixed outside, with expansion joints, as illustrated in fig. 144. Or if the elevation of the building will not admit of any such pipe being fixed outside, and the pipe is required to be carried down inside, galvanized wrought-iron pipe should be fixed with screwed joints and Y-junctions. Or instead of galvanized wrought-iron pipe, strong cast-iron pipe could be fixed, coated inside and out with solution, and with India-rubber expansion joints, as shown at A, fig. 146. The lead trap and lead branch waste being connected to the iron pipe by a gun-metal coupling union, as shown at b.

19. As the anti-syphoning pipe would only be slightly affected by the hot water sent down the waste-pipe, that could be fixed in lead in the usual way, connected by lead branches to the lead branch wastes by wiped soldered joints.

Fig. 146.