743 



WATER-POWER. 



WATER-PROOFING. 



748 



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 ^ths of an inch for a 2-inch pipe, ^ths of an 

 inch for a 6-inch, fths 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 meetiny 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-works, 

 for at the present day the ordinary cast-iron pipes are tested to a pres- 

 sure of 300 IDS. on the square inch ; and in the case of the great 

 Liverpool pipes the pressure was even carried to 600 Ibs. 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-pipe 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 jiurpose as lead, on account of the greater ductility of the latter 

 metaL 



WATER-POWER and WATER-PRESSURE ENGINES. The 

 weight and the impetus of a stream of water are frequently employed 

 in mechanics as a source of motive power for the machinery used in 

 industrial operations, in the form of the various kinds of water-wheels; 

 and of late years the law by which water and other similar (practically) 

 incompressible fluids transmit pressure in every direction, and tend to 

 assume a constant level in any reversed syphon, has been made to serve 

 the purposes of mechanics by furnishing the power exerted by the so- 

 called hydraulic cranes and the water-pressure engines. The term 

 tc'iiii--pioer, therefore, simply refers to the force developed by the 

 water in its natural fluid state ; and it acts either by its weight, its 

 impact, or by its power of transmitting an effort exercised upon any 

 part of its circumference. In an overshot wheel the water acts almost 

 exclusively by its weight, which is applied on one aide of an unbalanced 

 wheel ; in an undershot wheel the water may often exercise power by 

 reason of the velocity with which it is animated when it strikes the 

 floats ; in a reaction wheel the power is produced by the escape of the 

 water from a pipe reacting upon the air surrounding the apparatus ; 

 and in the hydraulic cranes, the power is obtained by forcing water into 

 a raised cistern, from whence it is able to act, as workmen say " with 

 a head," upon the underside of pistons bearing loaded surfaces. Virtu- 

 ally it is the weight of the water which produces the useful effect 

 in all these cases ; but the interferences with its action are so numerous 

 as to justify the popular distinctions above referred to. 



The various descriptions of WATER-WHEELS are described under that 

 head ; at present it is intended only to notice the water-pressure 

 engines used in mining operations, and the hydraulic cranes ; because 

 they constitute applications of water-power of so peculiar a nature, as 

 not to justify their being included under the more generally known 

 classification of water-wheels or engines. The mode of their applica- 

 tion is also different from that of the ordinary forms of water-engines ; 

 the latter being usually employed for the purpose of driving machinery 

 or mill work, the former for raising water, or for hoisting weights 

 only. 



The vxtter-preteure ewjinet are constructed upon the principle of 

 collecting, in a tube of a certain height, a quantity of water, and in 

 allowing that water to escape when it has produced the desired effect. 

 This is accomplished by placing the underside of a piston, moving in a 

 vertical cylinder, in communication with a column of water, and in 

 cutting off that communication when the piston has arrived at the 

 head of its stroke. The pressure of the column of water acts, in fact, 

 to raise the piston, to which the pump rods are attached ; and the 

 alternate downward motion is effected by the weight of the pump rods 

 themselves, in the same manner that the pump rods of the Cornish 

 engines work : the bottom of the cylinder is placed in communication 



also with the outflow, so as to allow the water to escape after it has 

 done its work. The passages for the water are opened and closed by a 

 series of tappets and equilibrium valves of a peculiar description, in 

 order to avoid any abrupt hydraulic jar from the change in the con- 

 ditions of flow in the descending main ; these details are, however, of 

 too complicated a nature to allow of their being represented here, 

 but they may be studied in the notice of the water-pressure engine at 

 Huelgoat in the ' Annales des Mines,' or in Burat's ' Ge'ologie 

 appliquee.' In the best engines of this description the useful effect 

 obtained is usually about 0'45 of the power exerted ; though it has 

 been stated that in the pumps lately executed at Freyberg, as much as 

 0'75 of the real power has been used. Mountainous districts are the 

 most favourable for the establishment of the water-pressure engines ; 

 for it is only in them that the necessary conditions for their economical 

 working occur naturally. These are, that a sufficiently copious supply 

 of water should exist at a considerable height above the seat of the 

 piston ; and that a free discharge for both the water which has served 

 as the motive power and for the water raised should exist. The Huel- 

 goat engine is placed at a distance of 360 feet from the surface, and it 

 raises the water from a mine 754 feet below the level of the cylinders; 

 the diameter of the piston is 3 feet 4| inches, its height 9 feet, and the 

 length of the stroke 7 feet 6J inches ; it makes, when in full work, 

 5J strokes in a minute, and raises through the total height of 754 feet, 

 in one lift, 396 gallons per minute ; there are two cylinders, but the 

 galleries are not sufficiently advanced to keep them constantly at work : 

 the descending and outflow pipes are 15 inches in diameter, the pump 

 barrel is 18 inches in diameter, and the ascending pipe is 10| in diameter. 

 M. Reichenbach has executed for the salt springs of southern Bavaria 

 a great number of these water pressure engines ; and it may be desir- 

 able to add that the one at Illsang is set in motion by a fall of water 

 328 feet in height, and that it raises, in one lift, not less than 1364 

 cubic feet of water. 



The hydraulic or water-pressure cranes were invented by Sir W. 

 Armstrong, and applied by him to the quays of Newcastle about the 

 year 1846, in the first instance; but subsequently, their use has 

 become general in other towns, wherein water is to be obtained under 

 considerable pressure. In these engines the water is admitted to act 

 upon one side of a piston working in a tight cylinder, and bearing a 

 piston-rod, upon the end of which is fastened a chain passing over two 

 fixed pulleys, under the pivot of the crane, and over a moveable one on 

 the head of the piston itself, in order to increase the distance traversed 

 by the load, at the expense of the power. The stroke of the cylinders 

 is usually long, and by thus passing the chain over the three pulleys, 

 the load is raised through a height equal to three times the stroke ; but 

 the load is correspondingly reduced in proportion to the effort exerted 

 on the piston. There are valves placed at the bottom of the cylinder 

 to close the access of the water to the piston, and to open the escape 

 passages ; and when the latter are opened the water escapes, and the 

 weight of the piston, and of the machinery attached, brings the piston 

 back to its original position. Relief-valves are placed near the slide- 

 valves, which give access or egress to the water, to guard against any 

 sudden shocks from changes of direction in the movement of the water 

 which might be likely to produce a hydraulic jar. The water-pressure 

 cranes used at Newcastle had cylinders 12 feet long by 1 foot in 

 diameter, and they worked under a head of water equal to 240 feet. 



The principle of the hydraulic press is, in fact, the same as the one 

 involved in the water-pressure engine and the hydraulic crane. It 

 consists in the faculty by which water transmits in all directions a 

 power exercised upon any portion of its surface ; the difference in the 

 mechanical arrangement being simply that in the hydraulic press 

 additional force is applied by means of levers and pumps, whereas in the 

 pressure-engines the statical pressure of the source of supply is alone 

 brought into operation. [HYDRAULIC PRESS; HYDRODYNAMICS.] 



WATERPROOFING. Textile fabrics, whatever be their character, 

 are pervious to water from two causes : namely, the existence of minute: 

 spaces between the individual fibres of the yarn, whether of silk, cotton, 

 wool, or flax ; and the rectangular meshes consequent on the process of 

 weaving. To close up these minute channels, as likewise the pores of 

 leather, so as to impart a waterproof quality to the material, has been 

 the object of a large number of patents, as well as of recipes which 

 have not been patented. Mr. Hellewell took out one of the earliest of 

 these patents, for a solution which should render cotton and other 

 fabrics waterproof. According to this plan, for a quantity of woven 

 material equal to 1000 Ib. weight, there are used 120 Ib. of rock alum, 

 80 Ib. of common whiting, and 200 gallons of water. This mixture is 

 intended, by the chemical action of its ingredients, to yield a solution 

 of alumine, with which the cloth is saturated. After the saturation 

 the cloth is passed quickly through a vessel containing a solution, at a 

 temperature of 100 Fahr., of yellow soap in water, the proportions 

 being 3 Ib. of soap and 30 gallons of water to 50 Ib. of cloth. This 

 latter process is for the purpose of fixing the alumine in the interstices 

 of the cloth, and enabling it to resist the action of water. The cloth is 

 finally washed, to free it from any impurities. Mr. Hall patented a 

 method of waterproofing cloth by immersion. He describes two kinds 

 of solution employed for this purpose. 1st, two ounces of pulverised 

 alum are dissolved in a pint of distilled water ; one ounce of dry white- 

 lead is rubbed down in another pint of water ; and the two solutions 

 being mixed and allowed to settle, the supernatant liquor constitutes 



