8o Improvejnenls oil IVciter- Wheels. 



an ovcrfliot produces about double the effecSl of an underfliot 

 wheel. 



Hence it is obvious, that where water can be mac^e to aft 

 on a wlifcl by weight, it is much more etfedual than when 

 the fame water is made to a6l by impulfe. 



But where llie fall is lefs than about half the diameter of 

 a wltccl with buckets made in the ufual form, the difficulty 

 of filling them, aud the fliort time thev are able to retain the 

 water, are fuch great defefts, th;it in fuch cafes wheels with 

 "open float boards, on which the water afts partly or altooe- 

 ther by its impuli'e, have been found in practice to be more 

 advantageous. 



It occurred to me however, that, by adopting another form 

 of the buckets, they might be fo made as to be eafily filled, 

 and at the fiiiiie time capable of retaining the water in a fitna- 

 tion to produce nearly its full etleft, altogether by weight, on 

 a low fall. 



A wheel of the confiruftion T mean is reprefented in, the 

 figures. Contrary to the ufual practice, the water mult here 

 be poured into the buckets /row^ iviihin the fhroudiug -^^ 



How the filling of the buckets from within can he accom- 

 pliflied, may not at firft be obvious ; but a (light infpeftion 

 of the figure will fliovv that it may be done without the pen- 

 flock interfering with the arms of the wheel. 



The buckets in the figure empty themfelvcs bv means of 

 apertures the whole length of the buckets, but no wider than 

 juft fufficient to difcharge the water before they begin to 

 afccnd. 



References fo ihe Figures. 



Fig. I. (Plate III.) elevation of the water wheel. 



A, A, the penftock. 

 ' From B to C a part of the wheel is reprefented with the 

 flirouding removed, to fliow the form of the buckets and the 

 litualion of the water in them. 



aaa the apertures by which the water efcapes from the 

 buckets. 



Fig. 2. horizontal fe6lion of the wheel, and plan of the 

 penftock. 



b the aperture by which the water enters from the pen- 

 ftock to the buckets. 



RoBERTSox Buchanan. 



Rotlicfay, Nov. g, 1799. 



'■' The flirouding is a flnt ring, generally ofwooJ, of the diameter of the 

 wheel, I'ci ving to forni the ends of tiie buckets, or to conncft the floats, 

 cspreffud by the letter B, (Pl.uc HI.) -,■: 



Defcripfiori 



