X794' t^^s effect Iff water on machirary . Jiy 



..thej were in fact so easily to be obviated, as scarce- 

 ly to deserve the name of obstructions at all ; as will, 

 !■ trust, appear from what follows. 



The principal reasons why no attempts have been 

 made to construct mills on this plan, are the follow- 

 ing : 



itt. Were a mill to be placed upon the main bo- 

 dy of the stream, or river, there could be no way of 

 guarding against the effects of inundations, by means 

 of sluices, as at present, which turn off as much of 

 the water into another channel, as fhall be at any 

 time superfluous ; nor could the flow of the water 

 towards the wheel be entirely prevented when the- 

 machinery is meant to be, stopped. 



To obviate both these difficulties, it would only,, 

 however, be required to raise the supports on which 

 the gudgeons of the wheel rest at either end, to such 

 a height as to overtop the wheel 5 and to make these 

 gudgeons be received into an eye, fixed in a piece of 

 wood, that admitted of being raised upwards at plea-- 

 sure, in grooves provided in the cheeks for that pur- 

 pose. From each of these bonces let a chain be car- 

 ried upwards, and pafsed over a roi>nd axle, placed atr 

 a sufficient height above the wheel ; o\\ one end of 

 which let there be fixed a wheel with spokes, like 

 the wheel of a crane, by means of which, the water 

 wheel might be raised entirely out of the water , 

 whenever it fiiould be wanted to stop the mill, either 

 on account of a flood or otherwise *. 



* A» I. clo not mean here to eit,jlain/>flmVi//(<rj, but merely to deve- 

 lope frincifUi, it it unnecefsary to trouble the re.dcr wi;h i detail of t) e 

 maie ia which th'.i migbt be '.ftccipd,. which couU not be rendt • 



