WATER. 



thefe boards are not continued fo far as to join to the back. 

 ■of the next float, bccaufe that would make all the boards of 

 the wheel clofe, and prevent the free efcape of the air when 

 the water entered into the fpaces between the floats. 



As the water ftrikes with feme force, the riiing-board is 

 ver\- neceflary, to prevent the water from dalhing over the 

 float -boards into the interior of the wheel. 



This is the form of bread-wheel employed by Mr. 

 Smeaton in the great number of mills which he conftrufted ; 

 but although he fpeaks of the impulfe of the water ftriking 

 the wheel, he always endeavoured to make the top of the 

 breafting or crown of the fall as high as poffible, fo as to 

 attain the greateft: fall and the lead of the impulfive aftion. 

 All rivers and ftreams of water are fubjeft to variation in 

 height from floods or dry feafons, and in fome this is very 

 coiiliderable ; it was therefore neceflary to make the 

 crown I of the fall at fuch a height as that in the lowed 

 date of the water R, it would run over tlie crown in a Iheet 

 of three or four inches in thicknefs, and work the wheel. 

 When the water rofe higher in the mill-dam, it would then 

 have a preffure to force it through, and in that cafe would 

 ftrike the wheel fo as to impel it by the velocity. 



Mr. Smeaton was well aware that the power communi- 

 cated by this impulfe was very fmall. In fome cafes, where 

 the water was very fubjedt to variation, he ufed a falfe or 

 moveable crown, that is, a piece of wood which fitted to the 

 crown I, and raifed the furface thereof a foot or more, fo as 

 to obtain the greated fall when the water Hood at a mean 

 height ; but when the water funk too low to run over this 

 moveable crown, it could be drawn up to admit the water 

 beneath it. This effeft has fmce been produced in a more 

 perfeft manner by making the crown of the fall a moveable 

 (huttle, to rife and fall according to the height of the water in 

 the mill-dam, by which means ths inconvenience before- 

 jnentioned is avoided. 



Improvid Breq/l-<wheil., in ivhich the Water runs over ibe 

 Shuttle. — Fig. 7. is a feftiou of one of this kind. A is the 

 water which is made to flow upon the float-board B, and 

 urges the wheel by its weight only, the water being pre- 

 vented from efcaping or flowing off the float-boards by the 

 bread or fweep D D, and the fide-walls which inclofe the 

 floats of the wheel. The upper part of the bread D D is 

 made by a cad -iron plate, curved to the proper fweep to 

 line with the done-work. On the back of the cad-iron plate 

 the moving diuttle e is applied ; it fits clofe to the cad-iron 

 fo as to prevent the water from leaking between them, and 

 the water runs over its upper edge. F is an iron groove or 

 channel let into the mafonry of the fide-walls, and in thefe, 

 the ends of the Aiding diuttle are received ; / is an iron 

 rack, which is applied at the back of the diuttle, and afcends 

 above the water-line where the pinion g is applied to it 

 to raife or lower the fhuttle. The axis of the pinion is fup- 

 ported in a frame of wood II; A H is a toothed feftor and 

 balance-weight, which bears the fliuttle upwards, or it might 

 otherwife fall down by its own weight, and put the mill in 

 motion when not intended. G is a drong planking, which is 

 fined acrofs between the two fide-walls, and retains the water 

 when it rifes very high, as in time of floods ; but in com- 

 mon times the water rifes only a few inches above the lower 

 edge of the planking. When the fhuttle is drawn up to touch 

 this lower edge, the water cannot efcape ; but when the 

 diuttle is lowered down, it opens a fpace e through which 

 the water flows upon the float-boards of the wheel. This 

 was the form fird adapted for the falling-ihuttle, but its 

 condruftion has fince been much improved. 



Fig- 4. Plate II. is a feftion of tiie moll improved form 

 for a bread-wheel, taken from the Royal Armoury Mills, at 

 Vol. XXXVIII. 



Enfield Lock, ereded by Mcdrs. Lloyd and Ode!. The 

 general defcription of this, is like the former, but it is con- 

 drufted in a better manner, and unites ilrength with dura- 

 bility. The bread of mafonry is furmountedi by a cad-iron 

 plate A 25 feet high, which is let into the mafonry of the 

 fide walls at each end, and the lower part is formed with a 

 flanch, by which it is bolted to the done-bread at top. 

 This plate is made ilraight at the back for the fhuttle B to 

 lie againd, and it Aides up and down. The ends of the gate 

 are guided by iron groove pieces or channels which are let 

 into the done-work of the fide walls, and being made wedge- 

 like, they fix the ends of the cad -iron bread fad in its place. 

 The grooves are not upright, but inclined to the perpendicu- 

 lar fo much, that the plane of the gate is at right angles to 

 a radius of the wheel drawn through the point where the 

 water falls upon the wheel. D is a ilrong plank of wood, 

 extended between the iron grooves jud over the fhuttle. 

 When the fhuttle is drawn up it comes in contaft v/ith tiic 

 lower fide of this piece of wood, and dops the water ; but the 

 piece D is fixed at fuch a height, that the water will run 

 clear beneath it, unlefs its furface rifes above its mean 

 height. 



The float -boards of the wheel do not point to the centre 

 of the wheel, but are fo much inclined thereto that they ate 

 exaflly horizontal at the point where the water fird flows 

 upon them. In this way, the gravity of the v/ater has its full 

 effeft upon the wheel, and the boards rife up out of the 

 tail-water in a much better pofition, than if they pointed to 

 the centre of the wheel ; and this is more particularly ob- 

 fervable when the wheel is flooded by tail-water penned up 

 in the lower part of the race, fo that it cannot run freely 

 away from the wheel. The diineniions of this wheel are as 

 follow : — Diameter 18 feet to the points of the floats, and 14 

 feet wide ; the float-boards are 40 in number, each 16 inches 

 wide, and each rifing-board 1 1 inches wide. The wheel is 

 formed of four caft-iron ciicles or wheels, each 14 feet 8 

 inches diameter, placed at equal didances upon the central 

 axis, which is 14 feet 8 inches long between the necks or 

 bearings, and 9 inches fquare ; the bearing-necks are 9! 

 inches diameter. The wheel is calculated to make four re- 

 volutions />«r minute, which gives near 35 ieei per fecond for 

 the velocity with which the float-boards move. The fall 

 of water is fix feet, and the power of the wheel, when the 

 fhuttle is drawn down one foot perpendicular, equal to 

 28-horfe power. 



Breajl-Wheel ivith tiuo Shuttles. — In this wheel the piece 

 of wood marked D in the lad figure, is fitted into the groove 

 of the fhuttle, and is provided with racks and pinions to 

 (lide up and down, independently of the lower fliuttle. 

 The intention of this is, to make the lower Ihattle rife and 

 fall, according to the height of the water, fo that the water 

 fball always run over the top of it, in the proper quantity 

 to work the mill with its required velocity, whild the upper 

 fhuttle is only ufed to dop the mill by fhutting it down 

 upon the lower fhuttle, and preventing the water from run- 

 ning over it. This plan is ufed when the mill u to be regu- 

 lated by a governor, or machine to govern its velocity ; in 

 that cafe the governor is made to operate upon the lower 

 fliuttle, and will raife it up, or lower it down, according as 

 the mill takes too much or too little water, and this regulates 

 the fupply ; but the upper fhuttle is ufed to dop the mill, 

 and by this means the adjullment of the lower fhuttle is not 

 dedroyed, but when fet to work again, it will move with its 

 required velocity. Fig. 3. Plate II., Water-wheels, is a fec- 

 tion of one of the water-wheels at the cotton-mills of MefTrs. 

 Strutt, at Belper, in Derbyfliirc. The width of this wheel 

 13 very great, and lo rendi-r ihe fhuttka A B firm, a drong 

 M g'^*ti"g 



