WATER. 



for this reafon they are omitted in the drawing, which is in 

 feme degree imaginary, as it reprefents the engine detached. 



This machine is more limple than the preceding, as it 

 performs more work by fix pumps of ten inches bore and 

 4^ feet ftroke than the other by fixteen pumps of feven 

 inches bore and 2^ feet ftroke, and therefore with much 

 lefs lofs of power by friftion ; and as the cranks only 

 work in one direction, they work much more pleafantly 

 than when there are pumps at both ends of each lever, be- 

 caufe in that cafe the flrain on the cranks, connefting-rods, 

 and the fulcrums of the levers, in faft on all the joints, is 

 alternately in different diredlions, and if there is any fhake 

 or loofenefs in the joints, it produces jerks and irregularities. 

 By ufing three barrels and triple cranks, the fupply of 

 water, forced into the main-pipe, is more equable than when 

 four are ufed, though not perfeflly fo. The perpendicular 

 motion produced by the arches and chains, is a great advan- 

 tage in making the barrels wear equally. 



In order to enable this engine to work as long as pollible 

 in each tide, and after the velocity of the motive water is 

 abated, it is contrived to adjufl the refiftance to the dimi- 

 nifhed power. This is done in the moft fimple manner by 

 a fmall cock and pipe in the chamber of each pump-barrel ; 

 juft above the fudlion-valve from this cock, a rod of com- 

 munication rifes up to the ftage to turn it by, and this cock 

 being opened will admit air into the barrel when the pifton 

 is drawn up, fo that the water of the river will not be drawn 

 up into that barrel ; and in confequcnce, it will become in- 

 active, and the wheel will be relieved from the load of work- 

 ing it. In this way, the load of the engine is adapted to 

 the power of the tide at its different periods ; but when all 

 the three barrels are thus relieved by opening the air-cocks, 

 the motion of that engine becomes a ufelefs loud friftion of 

 the piflons and movements ; and to relieve this, the ihaft or 

 axis of connexion between the axis of the trundle and the 

 triple crank, is provided with the means of diluniting or 

 uniting them whilil in motion, fo that one engine will itand 

 Hill whilil the other is at work. 



The principal dimenfions of this machine are as follow : 

 — The water-wheel is thirty-two feet diameter, meafuring 

 to the outlide of the float -boards ; the length of the float- 

 boards fifteen feet and a half, and their breadth four feet 

 and a half; the number of float-boards twenty-four. At 

 each end of the axis is fixed a cog-wheel, fourteen feet dia- 

 meter, with eighty cogs : each of thefe turns a trundle of 

 twenty-three ftaves, fixed on the axis of the cranks, which 

 are triple ; that is, three cranks are formed fide by fide on 

 the fame axis, and bent in different direftions, fo as to pro- 

 duce a continual aftion. Each crank actuates a lever or 

 working beam eighteen feet long, which is poifed on a ful- 

 crum in the middle, and gives motion to the pump-rods by 

 an arch-head and iron chains. The pump-barrels are ten 

 inches diameter, and the piitons make ftrokes of four feet 

 and a half long ; they are forcing-pumps, and three barrels 

 are combined together, to throw the water into one mam 

 pipe, which conveys the water into the town ; the higheft 

 elevation to which the water is ever lifted is a hundred and 

 twenty feet. The cranks, beams, and pumps, at each fide 

 of the wheel, are exaftly fimilar, fo that the wheel adluates 

 fix pumps. 



This machine was erefted, under Mr. Smeaton's direftions, 

 in 1767, and worked conilantly for fifty years, when the 

 timber-work becoming decayed, it was rebuilt in 181 7, with 

 caft-iron inllead of wood, and has been lately fet to work. 

 The principal proportions of Mr. Smeaton's defign have 

 been preferved, but the great levers have been fupprefTed, and 

 the cranks are placed over the fame pumps as the former. 



Mr. Smeaton's Pump Machine at Stratford IVater-works 



This IS fo like the laft, that we fhall only give the principal 

 dimenfions, as an example of the beft. proportions for a ma- 

 chine with a breaft-wheel, the laft being underlhot. The 

 water-wheel was fixteen feet diameter and eight feet wide • 

 upon its axis was a cog-wheel of eleven feet and a half dia- 

 meter, with feventy-eight cogs, which turned a cog-wheel of 

 five feet one inch diameter, with thirty-five cogs. This was 

 fixed upon the axis of the cranks, which were three in number 

 and by means of three beams gave motion to three forcing- 

 pumps nine inches diameter and two feet and a half length 

 of fl;roke, lift of the water 84 feet. In addition to the pair of 

 cog-wheels juft mentioned, there was another pair, of different 

 proportions, fixed clofe to the fides of the others, and by a 

 fimple contrivance either pair could be brought into aftion, 

 and the other pair would then be difengaged. The fecond 

 wheel, which was fixed in the axis of the water-wheel, was 

 nine feet eight inches diameter, with fixty-fix cogs, and the 

 wheel on the axis of the cranks which belonged to it had 

 forty-feven cogs. The intention of thefe two lets of wheels 

 was to adapt the water-wheel to >\'ork equally well when it 

 was flooded and impeded in its motion, as when the water was 

 low ; for when the quick motion was in ufe, the cranks made 

 15.6 revolutions per minute, whilft the water-wheel made 

 feven revolutions. But when the flow motion was in ufe, 

 the cranks would make 15. i revolution , per minute, whilft 

 the water-wheel made eleven. This machine is feven horfes' 

 power. 



The Pump Machine at Marly, near Paris, being fo much 

 celebrated on account of its magnitude and the multiplicity 

 of its parts, we fliall be expefted here to give ionie account 

 of it, which we have taken from Belidor, and we fliall fub- 

 join a few remarks upon its conftrudion, from which it will 

 appear we do not recommend it as a model. 



This machine is fituatcd between Marly and the village 

 La Chauflee. In that place the river Seine is penned up 

 partly by the machine and partly by a dam, which keeps up 

 the water ; but in order that the navigation may not be in- 

 terrupted, a canal has been cut, two leagues above Marly, 

 for the paflage of boats and barges. There has been erefted, 

 about thirty-five fathoms from the machine, a contrivance, 

 called an ice-breaker, to prevent floating pieces of ice or 

 tiniber, which come down the ftream, fmm damaging the 

 machine, and the better to fecure the pen-ftocks, and the 

 channels in which the watcr-wheels move. There is a grate 

 of timber to Hop whatever may come through the ice- 

 breaker. 



The water is raifed to its deftined height by the force of 

 fourteen undcrfliot water-wheels, which work the pumps at 

 three different ftages : firft, one fet of pumps to lift the 

 water from the river, to a refervoir placed up the hill two 

 liiindrcd and thirteen yards from the river, and at the eleva- 

 tion of a hundred and fixty Englilh feet above the level of 

 the Seine. The power of the wheels is conveyed alfo to 

 this place by chains, in order to work a fecond fet of pumps, 

 which force the water to the fecond refervoir, a hundred 

 and eighty-fix feet higher, and therefore three hundred and 

 forty -fix feet above llie river, and fix hundred and ninety 

 yards diitant. At this fpot is a tliird fet of pumps, to 

 throw up the water frcm the latter to the fummit of a tower 

 a hundred and eighty-nine feet higher, and at a diftance of 

 one thoufand three hundred and thirty yards from the river 

 up the mountain. The whole elevation is rather more than 

 five hundred and thirty-five feet above the river. From the 

 ciftern in the tower the water is conveyed, by an immenfe 

 aqueduft, to the gardens of Marly. 



The breadth of the machine comprehends fourteen water- 



courfes, 



