WATER-PI l'ES. In addition to what has been said on the subject of the flow of water in pipes under PIPE and WATER SUPPLY, it may be desimble here to mention a few practical matters connected with their manufacture and use.
The wooden pipes formerly employed were made from elm trees, and of about 14 or 15 feet in length, the diameter rarely exceeding 9 inches; • the interior was bored out by an auger ; the joints were of the kind known as the spigot and faueit, in which one end of the tree was tapered for a length of about 9 inches, and the end of the pipe destined to receive that taper was rimerrd out to fit It. These pipes have now been entirely abandoned, on account of their not being able to resist the pressures they are exposed to in modern works, and of the bad flavour they communicate to the water.
The cast-iron pipes aro laid with socket joints run with lead ; the depth of the joint being proportioned to the diameter of the pipes, but even in the largest it does net exceed 6 or 8 inches. A great effort has lately been made to introduce turned and bored joints for water distribution ; but the disturbance of the ground, and the unequal dilatation of the pipes, have hitherto prevented the successful applica tion of that system. It is customary to cast the smaller pipes, that is to say those of from 2 to 3 inches in diameter, in lengths of 6 feet each ; and the pipes of greater dimensions in 9 feet lengths. The thickness varies between Atha of an inch for a 2-inch pipe, Lths of an inch for a 6-inch, :ths of an inch for a 12-inch, and 1: for a 44-inch pipe ; the latter dimension is the largest hitherto adopted, and the only instance recorded of the use of such pipes is in the great Riving ton Pike supply to Liverpool. Of late years an attempt has been made to introduce the wrought-iron pipes of large diameter, coated externally with asphalte, on Chameroy's patent; but in practice so many inconveniences have been found to be attached to them, that the cast-iron pipes are now almost exclusively used in the ground, when the water is under pressure.
Glazed earthenware pipes are frequently used to convey water, when it is not under pressure ; but the difficulty of keeping the joints water tight has hitherto prevented this material from being much used for water supply. From the nature of the earth used in the manufacture of stoneware pipes, their length cannot exceed 3 feet ; and conse quently the number and expense of the joints would be a fatal objection to any such application.
As to lead pipes, the joints are made by soldering the two ends of the pipes together, the ends meeting butt, as workmen say. Up to a diameter of 2 or 3 inches lead pipes can be drawn ; beyond that dimension they are formed by rolling sheet-lead over a mandril, and then soldering the longitudinal lap. Joints so made are hardly able to resist the effect of the enormous pressures used in modern water-worka, for at the present day the ordinary cast-iron pipes are tested to a pres sure of 300 lbs. on the square inch ; and in the case of the great Liverpool pipes the pressure was even carried to 600 lbs. per inch. As a general rule lead pipes are made of an inch in thickness. The junction of service-pipes upon cast-iron mains is effected by fixing a brass ferrule to the latter, and soldering the service-pip to the ferrule ; and it would appear that the intervention of the ferrule is sufficient to prevent the galvanic action between the iron and the lead, which would otherwise take place. All the small taps, valves, &c., upon service-pipes are made of brass; but the plugs, sluices, and valves, upon the mains are usually made of cast-iron. Zinc is rarely used for the purposes of water supply, and it is never used for the service-pipes; wrought-iron pipes themselves are not so much used for this purpose as lead, on account of the greater ductility of the latter metaL