WATER. 



the piftons would defcend into the barrel, and might there- 

 fore be leathered with cups like other pumps, fo as to be 

 quite tight without immoderate friAidn. This machine was 

 propofed by a Mr. Cooper in 1784, who obtained a patent 

 for it, and Dr. Robifon has again propofed it with re- 

 commendation. 



Mechanifm for equalling the Motion of Water-WheeU 



When a part of the machinery of a mill is fuddenly de- 

 tached from the firft mover, or fuddenly connefted with it, 

 the load of the machine is either increafed or diminifhed ; 

 and the moving power remaining the fame, an alteration in 

 the velocity of the whole will take place ; it will move 

 fafter or flower. Every machine has a certain velocity, at 

 which it will work with greater advantage than at any other 

 fpeed ; hence the change of velocity arifing from the above 

 caufe, is in all cafes a difadvantage, and in delicate opera- 

 tions exceedingly hurtful. In the cafe of a cotton mill, 

 for inftance, which is calculated to move the fpindles at a 

 certain rate, if from any caufe the velocity is much in- 

 creafed, a lofs of work immediately takes place, and an in- 

 creafe of wafte from the breaking of the threads, &c. ; on 

 the other hand, there muft be an evident lofs from the 

 machinery moving too flow. In fteam-engines this evil is 

 remedied by a contrivance called a governor, which we have 

 already defcribed in our article SxEAM-^n^/nf. 



Governors are fometimes apphed to water-wheels, and 

 made on various conftruftions. Smith-bellows have been 

 applied to that ufe, the upper board rifing and falling on 

 any augmentation or diminution of the velocity of the lower 

 board, which received its motion from the mill, and forced 

 air into the fpace beneath the upper board ; from this fpace 

 the air was permitted to efcape by a pipe with a cock. If 

 the lower board worked fafter than the air could efcape, 

 the upper board would rife, but if it moved flower, then 

 the board would fink ; and this rifing and falling was applied 

 to regulate the fliuttle of the water-wheel, not by the force 

 of the bellows alone, but the bellows were made to throw 

 the wheel- work of the mill into aftion, either to raife or 

 lower the fhuttle. 



Of late years a new kind of water-wheel governor has 

 been introduced, the principles of which are nearly the fame 

 as the governor of a iteam-engine. It has a revolving pen- 

 dulum, which receives its motion from the mill, and in pro- 

 portion as the machinery moves fafter or flower, the cen- 

 trifugal force afts with greater or lefs force upon the balls 

 of the governor, making them approach to, or recede from, 

 the perpendicular axis. This raifes or deprefles an iron crofs, 

 which Aides upon the perpendicular axis of the revolving 

 pendulum, and by ailing on a lever, is made to engage the 

 fluice with a train of wheel-work, which is kept in conftant 

 motion by the power of the water-wheel. When this train is 

 connefted with the fluice, it operates upon it fo as to enlarge 

 or leflen the paflage of the water to the water-wheel, and by 

 augmenting or lefiening the quantity of water falling on the 

 wheel, increafes or diminiflies its fpeed. 



This fluice is made on the principle of the throttle-valve 

 of fteam-engines. In order that it may be moved by a fmall 

 power, it is poifed on an axis of motion palling through the 

 middle of the fluice. When it is turned edgeways to the 

 ftream of water, it makes no obftruftion ; but if it is turned 

 perpendicularly, it clofes the paflage of water, or by placing 

 it more or lefs obliquely, it alters the area of the paflage for 

 the water. 



The axis on which the fluice turns, if horizontal, fliould 

 be one-third of the height of the fluice from the bottom, in 

 order that the prefTure of the water above the centre may 

 balance that below. 



So long as the machinery is moving at a proper velocity, 

 this wheel-work of the fluice apparatus is not connefiked 

 with the fluice, and it remains at reft. But if the mill goes 

 too flow, the crofs is deprefl"ed, and ftriking the lever in 

 an oppofite direftion, connedls the fluice with a different 

 part or train of wheel-work, which has a motion in a contrary 

 direftion to the former, and fo produces a contrary effeft on 

 the fluice. 



The train of wheel-work is fo calculated, as to reduce 

 the aftion on the fluice to a very flow motion, and it is 

 found, from experience, that this is neceflary. Where the 

 area of the aperture is too fuddenly changed, the effeft on the 

 water-wheel would be too violent. See a more complete 

 defcription of this contrivance in Vol. XXIII. MiLL-^orl. 



On the Conflru8ion of the Wheel-race and Water-courfe. — 

 The wheel-race fliould always be built in a fubftantial manner 

 with mafonry, and if the ftones are fet in Roman cement, it 

 will be much better than common mortar. The earth behind 

 the mafonry fliould be very folid, and if it is not naturally 

 fo, it ftiould be very hard rammed and puddled, to prevent 

 percolation of the water. This applies more particularly to 

 breafl;-wheels, in which the water of the dam or refervoir ia 

 ufually immediately behind the wall or breaft in which the 

 wheel works, a floping apron of earth being laid from the 

 wall in the dam to prevent the water leaking. The wall of the 

 breaft fliould have pile planking ( fee Canal ) driven beneath, 

 to prevent the water from getting beneath, becaufe that might 

 blow up the foundation of the race. The ftones of the race 

 are hewn to a mould, and laid in their places with great care ; 

 but afterwards when the fide walls are finiflied, and the axis 

 of the wheel placed in its bearings, a gauge is attached to 

 it and fwept round in the curve, and by this the breaft is 

 drefled fmooth, and hewn to an exaft arch of a Circle : 

 the fide walls in like manner are hewn flat and true at the 

 place where the float-boards are to work. It is ufual to make 

 the fpace between the fide walls two inches narrower at each 

 fide, in the circular part where the floats aft, than in the 

 other parts. 



In fome old mills the breaft is made of wood planking, 

 but this method has fo little durability that it cannot be re- 

 commended. In modern mills, the breaft is lined with a call- 

 iron plate, but we do not approve of this, becaufe it is next 

 to impoflible to prevent fome fmall leakage of water through 

 the mafonry, and this water being confined behind the iron 

 breaft cannot efcape, but its hydroftatic preflure to force up 

 the iron is enormous ; and if the water can ever infinuate 

 itfelf behind, the whole furface of the plate rarely fails to 

 break it, if not to blow it up altogether. This is beft guarded 

 againft by making deep ribs projefting from the back of 

 the plate, and bedding them with great care in the mafonry; 

 thefe not only ftrengthen the plate, but alfo cut off the 

 communication of the water, fo that it cannot aft upon 

 larger furfaces at once, than the ftrength and weight of the 

 plate can refift. Stone is undoubtedly the beft material for 

 a breafting. In overfhot-wheels the lol's of water, by running 

 out of the buckets as they approach the bottom of the 

 wheel, may be confiderably diminiftied by accurately form- 

 ing a fweep, or cafing round the lower portion of the 

 wheel, fo as to prevent the immediate efcape of the water, 

 and caufing it to aft in the manner of a breaft-wheel, which 

 has been already defcribed. While this improvement re- 

 mains in good condition, and the wheel works truly, it pro- 

 duces a very fenfible effeft; but it is frequently objefted to, 

 becaufe a ftick or a ftone falling into the wheel would be 

 liable to tear off part of its ftirouding, and damage the 

 buckets ; and again, a hard froft frequently binds all faft, and 

 totally prevents the poflibility of working during its conti- 

 N 2 nuance ; 



