Mr J. G. Stuart on the Turbine Water-Wheel 161 



diameter than that part. It is keyed on the bottom of the 

 pipe just below the circular opening in the floor, and so low 

 that its upper surface is level with the flat circumference of 

 the wheel, and kept in its place by the stay-rods of the pipe, 

 so as to be about \ of an inch clear of that circumference all 

 round. On this disc are erected the guide-curves, equal in 

 number to the curves of the wheel, and in such a shape as to 

 throw the water at the proper angle on them as it flows out. 



The sluice-cylinder is bolted to the four large beams of the 

 floor, and is of such depth that its lower end comes down to 

 within a few inches of the top of the upper circumference of 

 the wheel. It is bored through, so that the sluice may fit 

 well, and be readily moved up and down in it. 



The sluice itself is another cast-iron cylinder, fitted to the 

 inside of the last mentioned one, going down as low as to 

 rest on the outer circumference of the centre disc, and rising 

 so high as, when fully up, to leave 9 in. of opening between 

 that disc and it. This sluice is vsrought by three rods work- 

 ing in screws, communicating with a triangle at the top by 

 means of studs and levers from eaoh rod. The triangle is 

 wrought by bevel wheels and shaft from the outside of the 

 wheelhouse. 



The mode of working the wheel is thus : — 



The water coming into the wheelhouse or reservoir from 

 the front lead, fills it up, standing on the centre disc and 

 flooring, to the height of the top of the water in the front 

 lead. The sluice is then raised, when the water flows out 

 under it, off" from the curves of the centre disc, which thus 

 remains fixed and stationary, on to the curves of the wheel, 

 which, yielding to the pressure so exercised upon its curves, 

 moves round in the direction of the efflux of the water from 

 the centre disc ; the sluice is raised until the necessary speed 

 is attained, or until the water is vented by the wheel as fast 

 as it is supplied to the reservoir from the front lead, care 

 being taken that it is not allowed to go faster away, — that is, 

 that the head of the water in the reservoir is always main- 

 tained at its full height, — the level of the front lead. 



I have thus minutely described each part of the wheel, 

 and, I trust, made the description intelligible by reference to 



VOL. XLI. NO. LXXXI. — JULY 1846. L 



