Where running sand or subsoil-water is likely to be met with in the ground, or where the drain is laid close to a water-course, and where special precautions must be taken to exclude a possible percolation of water through the joint, and provided there is nothing otherwise to interfere with a rigid joint being used, it will he found an advantage to adopt one of the other forms of joints. such as the spigot-and-socket joint with provision for pouring in liquid cement.

Hassall's patent safety joint (double-lined) can be used with advantage, as it can be readily and rapidly made in water; wherever thoroughly reliable work is desired, this is undoubtedly the best pipe to use. I quite coincide with the opinion expressed by Mr. H. Percy Boulnois. M.I.C.E., late City Engineer, Liverpool, in his Municipal and Sanitary Engineer's Handbook, that "Has-sail's pipe is the l>est at present known to engineers and surveyors." It will be seen from the illustrations that there are two rings of composition in the socket with a space of about 1 1/2 inches between them, and that there are corresponding collars in the spigot The mode of making the joint in the trench is as follows: Lay a band of plastic cement, marked a in Fig. 323, a sixteenth of an inch in thickness, on the whole face of the composition lining, and lay another hand, marked b, in the groove of the outer collar cast round the spigot. Then place this spigot end inside the socket of the pipe lined with plastic cement, and press it home with an iron bar or other suitable appliance, until the end of the spigot of the one pipe, marked c, abuts against the inner shoulder within the socket of the other pipe, marked D. The two hands of plastic cement will thus be compressed us shown in the drawing of the completed joint, leaving an annular space or groove between the inside of the socket of one pipe and the outside of the spigot of the other pipe. This annular space is filled with a mixture of five-and-a-half parts of neat Portland cement and three parts of water. Before pouring this cement into the annular groove through the opening F, a piece of plastic cement must be put under the bridge E (which divides the two holes F and g), to block up the space underneath this bridge, so as to compel the Portland cement to run in one direction round the whole of the annular space until it appears again at the opening G; unless it does so appear the joint must be remade. The Portland cement should be poured through a funnel placed in the opening P, so as to run round the groove under pressure, and drive out all air or water that may be in it The plastic cement is supplied with the pipes. The Portland cement should be perfectly free from lumps, and well mixed (but not until it is required for use), and should be well stirred before being poured into the joint

Fig. 323.  Hassall's Double lined Drainpipe Joint

Fig. 323.- Hassall's Double-lined Drainpipe Joint.

If pipes are jointed and the Portland cement is not poured in at once, the two openings, F and G, should be covered by a flat piece of clay, so as to keep the annular space free from grit, etc, until such time as it is filled with Portland meat.

The advantages of this joint ere: (1) it is airtight and water-tight; (2) the joints are the strongest parts of the sewer; (3) a true invert is secured by tin-pipes being centred properly when the bituminous bands are cast on; (4) the pipes can be laid in water; (5) in consequence of the joints being water-tight, the sizes of the pipes may be reduced; (6) the jointing material cannot be washed out; (7) the sewage can be passed through the pipes directly they are laid, without affecting the joint.

A pipe designed very much on the lines of Hassall's is Button's patent "Secure" joint, shown in Fig. 324. On the spigots and in the sockets of the pipes, a bituminous material is cast by means of improved and patented apparatus. In these cast rings, grooves are formed in such a way that, when the spigot of the pipe is placed in the socket, an annular groove is obtained, into which cement is run to seal the joint. The cast rings have true bevelled surfaces which allow of easy fixing, and when the groove has been tilled with cement, a perfect key is made, which renders the joint not only strong but absolutely water-tight.

Another well-known pipe, for which cement is used in completing the joint, is Green's patent "Truinvert" pipe, shown in Fig. 325. The object of this patenl is to form a perfectly-level bottom or invert, to strengthen the socket at it-weakest point, and to make a triple joint in a cheap and effective manner. The inner socket is continued all round instead of being semicircular only, and thus forms a level invert whichever side up the pipe is fixed; at the same time it strengthens the socket all round instead of in one portion of the circle only, and it enables a triple in place of a double joint to made. It is claimed that this pipe secures true alignment of invert, increased strength in the socket, three gas and water-tight connections at every joint, and while allowing for a slight settlement when first laid, forms an absolutely rigid joint directly the cement sets.

Fig 324.   Button's Secure Joint.

Fig 324. - Button's "Secure" Joint.

The drawings and descriptive references thereto show clearly how these results are obtained. It should be added, however, that the inner joint 0 is formed by lining the socket with a small quantity of special waterproof cement, supplied free with the pipes Ames & Crosta's single-seal joint is shown in Fig. 326. In this joint the socket is made somewhat deeper than an ordinary one, and has a specially-formed sealing-chamber at the seat, so constructed that the jointing material, displaced from the sealing chamber by the spigot, is prevented from entering the pipes, and is forced into grooves funned on the spigot, thus giving a perfect seal at the seat of the socket. Studs or rest pieces are tunned midway in the socket, or thereabouts, to ensure a true alignment of the invert at the joints; this true invert is ensured without impairing the efficiency of the joint, the rest pieces being entirely surrounded with jointing material. A running-in hole and rising hole are funned in the socket, so that the space between the two sealing-chambers may l»e grouted with liquid cement. When jointing these pipes, the sealing-chamber at the seat of the socket should be filled with clay, plastic cement, or other jointing material to the dotted lines a, the spigot should then be forced home into the sealing-chamber, when the displaced jointing material will be forced into the jointing space, overlapping the end of the Spigot, thus forming a perfect seal at the seat of the socket. A fillet of the same material should be worked round the entrance of the socket, and the joint may then be grouted through the running-hole with liquid cement. If desired, liquid cement may be dispenseded with, and the joint made up in the ordinary way with stiff cement or clay:

Cross and Longitudinal Sections.

Cross and Longitudinal Sections.

Enlarged Section.

Enlarged Section.

Fig. 325. - Green's " Truinvert " Drain pipe Joint. A A. holes for pouring in the cement or composition: BB, strengthened and lengthened socket : CC, inner socket and reat; EE, chamber for cement or composition; FF, Stanford joint in new position.

Fig. 336.   Ames and Crosta's Single scale Drain pipe Joint.

Fig. 336. - Ames and Crosta's Single-scale Drain pipe Joint.