[ 79 J 



XITT. Account of fome IviprGvements-on 1^'afer-lVheeh. B/ 

 Mr. Robertson Buchanan, Engineer, GUifgozi'. 



To Mr. TlUulu 



DF.AR SIR, Glp-'gow, Ca.io, iFor. 



jt\ conx MILL in which I had an intcrcft having had 

 about two feet of its fall unoccupied, owing to the ovcrfliot 

 wheel having been too fmall in diameter, I was defirous to 

 apply this unoccupied part of the fall in fonie way to increafe 

 the |X)wer of the mill. Thinking over various expedients for 

 this purpofe, in Februarv 1798 an idea of a water-wheel oc- 

 curred to me, which I thought might be applied with great 

 advantage not only to the (ituation I had in view, but in all 

 otlier cales of low h\\<. Some circiimftance, however, pre- 

 vented me at the time from putting it in practice; but I had 

 afterwards, at diOcrent times, two models of it made; and in 

 November 1799 fent up the accompanving dcfcription of it to 

 my friend Mr. JNiundell, of Fludyer-llrect, requefting him to 

 give it to the public. Upon fome after reflcclion, however, 

 I conceived it belt, for fome time, to dclav its publication; 

 and accordin<:lv till now have allov/ed it to lie dormant. 



Soon after (iniiliir.g the drawing referred to in the de- 

 fcription, I thought the particular form of buckets there re- 

 prefented miLdit be a lilile altered, fo as to make them flill 

 more advantagcoufly contain the water. Upon ihowing the 

 alteration I propoled to my ingenious friend Mr. John Ro- 

 BKiiTON of this place, he was at confiderable pains to invef- 

 tigatc the iubjecf, and pointed out the form of buckets re- 

 prefented in fig. 3. 



Allow me further to direft your attention to the conftruc- 

 tion of the aims fliown in the figures. It is applicaljle to 

 anv kind of watcr-whecl ; and fincc 1790, when 1 firlt con- 

 ftruftcd a wheel with arms on that principle, a conllderable 

 number of large wheels have, in Scotland, been erc(::l:ed on 

 that plan, I iiiall annex a Ibort dekiriptiou of this conllruc- 

 tion of arms. 



I remain, 



Dear Sir, yours, 



Robertson Buchanan. 



Copy of the Defcripiion fent to Mr. Mundell. 



It has been afcertained, from the mofl accurate experi- 

 ments on water-wheels, that under liie fame circumftances 



an 



