7^ (J 2- the- effects of water on machinery. 2cj 



power, is now lost, from an inattention to obvious 

 principles in the construction of machinery. 



There are two cases which maj be considered as 

 the extremes- in the application of water to turn ma- 

 chinerv, "oi^. where the height of the fall that can be 

 commanded, is very great ; or where the water 

 moves nearly on a level bottom, without admitting 

 of a cascade or fall. If the means of applying water 

 to machinery, in these two circumstances, so as to 

 derive the greatest beneiit pofsible from its power, 

 be distinctly specified, it will be very easy to apply 

 the principles that will thus be developed, to any 

 intermediate cases that may occur. 



Water, as a moving power, may be made to act 

 ttpon machinery, either by its dead weighty or by its 

 impetus. 



When we speak of water acting by its dead weight 

 upon a wheel, it is meant to say, that it is so ap» 

 plied as to produce an effect similar to that of a mun 

 pulling a rope wound round the circumference of 

 that wheel, moveable upon its center ; or that of any 

 other kind of weight suspended fram the same rope. 



When it acts by its impetus, we mean the same 

 thing as if a stone were thrown, so as to strike, with 

 force, a bound fixed to the edge of a wheel, movfeable 

 upon its center. Such a stroke would make the 

 board move ; and by a repetition of these strokes, 

 a continued rotatory motion uiay be produced. 



Moit of the water mills in Britain are so con- 

 structed as that water acts upon them in both these 

 ways united ; but wherever the fall is considerable, 



