The double-seal joint for water-logged ground (Fig. 327) has the sealingchamber at the seat of the socket and rest pieces to ensure a true alignment of the invert, hut the socket is extended, and a collar is formed on the spigot with a sealing-chamber similar to the one at the seat of the socket In making the double-seal joint, the sealing-chambers at the seat of the socket and in the collar on the spigot should be tilled with suitable stiff-jointing material, and the spigot forced home; a perfect seal will thus be formed at each end of the joint. The cavity between the seals can then be grouted with liquid cement. Care should always be taken to lav the pipes with the dart on the top, as this mark will indicate that the pipes are laid in the correct position.

Within the last few months Wakefield's drain-pipe joint (Fig. :328) has been introduced with the object of overcoming the irregularity of invert caused by the settlement of the spigot within the socket, the improvement being effected by forming two corrugated ridges in the socket with a space between. By this contrivance the spigot end of the pipe will rest on four points in the socket, all the remaining space being occupied with Portland cement The method of making this joint is as follows: - On the shoulder of the socket place a band of mastic clay, then insert the spigot of the next pipe, taking care that the corrugations are always at the bottom, so as to be in position to receive the next pipe, and put a band of day round the mouth of the socket. Pour neat Portland cement grout through the hole a till it appears at the hole B, then leave it for a few minutes; in the interval, other joints can be dealt with in the same way, by which time the cement first run will be sufficiently set to receive the remainder without fear of bursting out the clay backing. Pour gently through the hole c till the crown portion of the joint ifl complete!. It is scarcely necessary to add that in the event of any of the clay being squeezed into the pipe it must be carefully raked out. As an alternative method of making the joint, advantage may be taken of the corrugations only, for truly inverting the spigot in the socket, and the joint may be made with stiff Portland cement in the usual manner. The principle of this joint is practically the same as that of the "Rest pipe. made about twenty years ago, but not now in the market.

Fig. 327   Ames & Crosta's Double scale Drain pipe Joint.

Fig. 327 - Ames & Crosta's Double-scale Drain-pipe Joint.

Fig. 328   Wakefield's drain pipe Joint.

Fig. 328 - Wakefield's drain-pipe Joint.

There are also a great many other special joints, such as the An her, the Paragon, Double Seal, and others.

Sykes's screw joint has recently been introduced, and is of quite another form than those previously noticed, inasmuch as the composition is cast on tin-pipes with a male and female thread to form a screw-joint. and in making the joint a cement composition is used, which is forced into all the interstices by the pressure exerted in screwing up. Fig. 329 sufficiently explains the principles and method of making this joint.

To make absolutely certain that no damage shall occur from a pipe-joint leaking after a lapse of years, which is often brought al>out by the pressure of the earth causing the drain to give way at the joint, it has been sought to increase their strength by encasing the drains in concrete. The Model By-laws which were introduced by the Local Government Board in 1877, prescribed that all drains should be so constructed, and this method has been insisted upon in all subsequent by-laws, regardless of the fact that what may have l>een the most effective method twenty years ago is not necessarily so to-day.1 Surrounding the pipe with concrete is both a clumsy and expensive expedient, as will easily be seen, especially where the drain has to pass under a building; and one great objection to it is the difficulty of access when it becomes necessary to make a connection to the drain required by any extension of the system. This method of embedding a pipe in a surround of 6 inches of concrete would increase the coat of a 6-inch drain under the most favourable circumstances by at leaat 5s. per lined yard.

Fig. 329.   Syke's Patent Drain pipe Joint.

Fig. 329. - Syke's Patent Drain pipe Joint.

1 At the time the Model By- Laws were issued , the only one of the special-jointed pipes here described in existence was Stanford's, and with the exception of Hassall's and Doulton's none of the others were known even five years ago.

Fortunately by the use of cast-iron we are enabled not only to obtain the desired strength, but also all the advantages that could be obtained from an ideally-constructed earthenware-pipe drain.