WATER. 



devoted to the water-machines, that is, five on the London 

 fide, and one on the Soiithwark fide. 



Mr. Smeaton's great Engine at the ffth Arch of London 



Bridge This machine is reprefented in perfpeftive, in 



Plate II. Water-works, Machines for raifng Water. The 

 view being taken from beneath the arch of the bridge, B B 

 reprefents the flarhng of the fourth pier of the bridge, 

 compofed of a vaft body of piles driven into the bed of the 

 river, and the interftices filled up with chalk and gravel. 

 Upon the heads of thefe piles, a fet of horizontal beams 

 are laid in the manner of joills, and all is made level by chalk 

 and gravel. 



The fifth pier C C is made in the fame manner. The 

 water-wheel F F G G is made of fiich a breadth as to fill 

 the fpace between the two ftarlings as exaftly as poflible, 

 without touching ; and the bearings for the gudgeons of 

 its axis are fupported upon head-ftocks E E, which reft 

 upon the ftarhngs. The water-wheel has four circular 

 rings F F F F, each fuftained by fix arms mortifed into the 

 axis ; each ring has twenty-four ftarts mortifed into it, and 

 to thefe are nailed the float-boards//, upon which the water 

 afts to turn the wheel round. 



Upon each end of the main axis is fised a large wooden 

 wheel H H, round which caft-iron rings of cogs are fixed 

 in fegmcnts. Thefe cog-wheels turn two trundles, which 

 give motion to the forcing-pumps, which are fix in number, 

 vi%. one three-barrelled pump on each fide of the water- 

 wheel ; but only one of the engines or triple pumps is (hewn 

 in the figure, for as the other is exaftly the fame, it is fuf- 

 ficient to defcribe one. The axis on which the trundle I is 

 fixed is of caft-iron ; it is connefted with a triple crank, one 

 arm of which is marked b, and two others are hidden behind 

 the frame : ghi are ftrong iron rods, joined to the cranks at 

 their lower ends, and to the ends of the great levers or re- 

 gulators K L M at the upper ends. 



The regulators are poifed on centres in the middle of 

 their length, and have arches /?/m at the other ends, which 

 are ftruck from the centres of motion, upon which arches 

 the chains are laid, to give motion to the pifton-rods of the 

 pumps N. 



By the motion of the water ftriking the float -boards, the 

 water-wheel is made to revolve on its axis, and the large cog- 

 wheel H with it. This turns the trundle I and the triple 

 cranks be, which, being arranged round the axis at equal in- 

 tervals, elevate and deprefs the crank-rods _§• A ( and regida- 

 tors K L M fucceffively, and give to the pump-rods and 

 piftons a vertical motion. 



The joints of the crank-rods ^ /ji are made to fcrew to- 

 o-ether round the crank-neck with brafs between ; by this 

 means they work very pleafantly, and when worn can be 

 fcrewed up tight again that they may have no fhake. The 

 crank-rods are each made in two lengths, each of which has 

 a flanch at the end, and they join at n in the middle of the 

 rod : the flanches are held together by three fcrews, fo as 

 they may be taken apart occafionally without difficulty, 

 when the pump-forcers are to be drawn out of the barrels 

 to new leather them. 



The joints at the end of the beam or levers are made 

 vrith braffes, and fcrews to adjuil them ; and fo are the cen- 

 tres or fulcrums of the levers. 



The levers or regulators are admirably well defigned to 

 be ftrong, with but little timber ; they are formed of two 

 pieces of timber, between which the caft-iron axis on v.'hich 

 they turn are placed ; and then the ends of thefe pieces are 

 bent to touch, and are kept together by hoops and fcrew- 

 bolts, fo as to make clofe joints. At the ends, feveral fmall 

 fquare pieces of wood are interpofed crofs ways in thefe 



joints at the ends of the lever, being let into both timber* ; 



by thefe, when they are firmly bound together, the two 

 pieces of timber are prevented from Aiding end ways upon 

 each other, fo as they form an excellent trufs-beam, for it 

 cannot bend or yield without ftretching one timber and 

 oomprefBng the other. 



The pump-rods are attached to the arches at the ends of 

 the beams by four iron chains each, as is fhewn in_^p-. 2. 

 The rod has a crofs-piece^ fixed on the top of it, to which 

 the two outfide chains are attrched, and the lower ends of 

 the fame chains are fattened at the lower end of the arch, 



Thefe chains aft to pull down the pifton-rods ; the other 

 two chains which return or raife the rods are faftened to the 

 top of the arch, and to the rods at the lower ends, as fhewn 

 in the figure. 



The pumps are forcing-pumps, and raife the water when 

 the piftons are depreffed : the lower piece of the triple 

 pump is a fquare iron-pipe or trunk, fcrewed fafl down 

 upon the groundfells of the engine-frame ; this is called the 

 fudtion-piece : it has a flanch at each end, to one of which a 

 lid is fcrewed, and the other joins it to tlie futlion-pipe R, 

 which brings up the water from the river. On the top of 

 the trunk, the three barrels N are fcrewed, each having 

 a valve in the joint, which allovi'S water to enter into the 

 barrel, but prevents its return. From the bottom part of 

 each barrel proceeds a crooked pipe q, which communicates 

 with another fquare trunk S, called the forcing-piece, hav- 

 ing valves at the joint, to prevent any water from getting back 

 into the barrels. On the top of the trunk over each valve 

 is a round hole, over which a lid is fcrewed, but can be re- 

 moved to clean or repair the valves when neceffary. Similar 

 lids are fcrewed on over openings into the fuftion-trunk, at 

 the back towards the cranks. At the ends of the forcing- 

 trunk S are flanches, one of which receives a lid like the 

 lower trunk, and the other flanch joins to the pipe s, which 

 conveys the water away from the pumps. 



The piftons or buckets of the pumps are fohd, that is, 

 without valves in them ; and their aftion is as follows : 



When the pifton of any of the barrels is drawn up, it 

 makes a vacuum in that barrel ; and the prefTure of the at- 

 mofphere on the fnrface of the water from which the fuftion- 

 pipe R draws, raifes the valve at the bottom of that barrel, 

 and fills it with water. At the defcent of the pifton, the 

 lower valve fhuts, and the water contained in the barrel can 

 find no paffage but through the valve in the forcing-trunk 

 S ; and when the pifton is drawn up again this valve clofes, 

 and the lower one opens to give a frefh fupply of water to 

 the ban-el. By the pofition of the triple cranks, it alwavs 

 happens that one or other of tlie barrels is forcing the 

 water into the force-pipes ; and as the ftrokis of the other 

 fet of pumps at the other end of the water-wheel are con- 

 trived to be intermediate or alternating to thefe, a conftant 

 fucceffion is kept up. 



The main-pipe s is continued to the fhore, to convey the 

 water into the ftreets. A wooden ciftern T is placed over 

 the pumps to hold water, and keep a conftant fupplv of it 

 above the piif ons to prevent leakage. The whole engine is 

 furrounded by a ftrong timber fence, which guards it from 

 the injuries it might receive from veffels or floating ice, 

 ftriking it at high water, when the water rifes above the 

 level of the ftarlings nearly to the axis of the water-wheel. 

 On the tops of thefe piles, a large itage is built, to ferve as 

 a road from the fhore to the engine, and the underfide of it 

 fupports the main-pipes, which convey the water afhore. 

 There are alfo other ftages in different parts of the machine, 

 to fupport workmen when repairing it ; thefe prevent the 

 whole £Dgi?e from being feen from the bridge at one \'iew, and 



for 



