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Mechanics.

and none go to those on the Middle, where the Effectwould be rather greater. Therefore the Orifice ofthe Pen-stock ought to be situated some little Heightabove the Middle or Horizontal Diameter of theWheel.

20. In order that the Water may have the greatestEffect on the Wheel, Dr. Barker has constructed itwith 24 Ladle-Boards, (instead of Buckets) of 18 In-ches Square; these Ladle-Boards pass through a qua-drantal Channel of the same Dimensions nearly, or alittle more than 18 Inches square, that the Motion maybe free. The Water entering on the Top of this Chan-

Pl XIII ne l * s kept wholly on the Boards, till it comes to thejr' e j Bottom, where it goes off without interrupting theMotion of the Wheel. The Contrivance is very use-ful, and may be easily apprehended by the Scheme, fwhere A D B E represents the Wheel with its Ladle-Boards, C the Axis, F the Jet or spouting Water,GHI the square Channel or Trough in which theLadle-Boards with the Water descend to I, where theWater is discharged from the Wheel.

21. In Fig. 2. you have a Section of the Sole or Pe- 'rimeter of the Wheel, and the Channel with the Ladle- \Boards in it; thus a be is the Sole of the Wheel, fgh i ;is the Section of the Channel open on the Part next the j

Fig. 2. Wheel by a narrow Slit, in which ^ Us the Part called ;

the Tongue, which projects from the Sole to sill up that jSlit, that the Water may not run through it; lm n 0 jis one of the Ladle-Boards put on upon the Supporter ■p q, which goes through the Tongue and Sole of the jWheel, with a Hole behind at through which a iKey or Wedge, like a Piece of Wood, being driven, ‘fastens it with the Board to the Wheel. Thus you fee by :this Means how great the Force of the Water must be ,on the Wheel, and how much less will suffice here thanin the common Way.

22. As to an UnderJhot-lVheel , it is evident there canbe only the Force of the Impulse from the Water onsuch a Wheel , and therefore the Height of Water re-maining the same, there must be a larger Aperture ofthe Pen-stock, that so a greater Quantity of Watermay come upon the Float-Boards in the lame Time,

to