420 RepI^ to the Letter cf A, G. on Thrafhing Machines, Nor* 



I confidered to be of little utility; and maintained that no bene- 

 iit could be derived frc m k ^.owing the dimenfions of wheels and 

 junions, u:ilt:-fs the velocty of the moving power was alfo ex- 

 plained. Id doing thefe things, I invented no machine for him; 

 I njerely reafonc-d upon tlie particulars turnifhed refpeOing thofe 

 lie had conftruded and erected ; and whether I reafoned cor- 

 rcQly or not, cannot be afcertained from the letter now before 

 me. In a vague way, he fays, that a mill built by theory may 

 i Ml iliort of txpeclation when put into practice ; the trurh of 

 ^vhicli, as a general pofition, I readily allow. Nay more, i^ 

 woulii not be tliihcult to biing proofs of its recftitude, even from 

 tlie account given by your correfpondent of his own undertak- 



AViih regard to the comparative utility of fmall and large ma- 

 chinesj I believe there can be but one opinion among thofe w^ho 

 are difpofed to inveltigate the bufinefs with prccifion. Perhaps 

 fmall macliines, in certain cafes, may be ufed with fome degree 

 of fucccfs, particularly if barley and oats are only cultivated, or 

 where tlie Itraw is fhort and foft ; but as Ihakers and fanners can- 

 not be annexed to them, at lead when worked by one horfe, I 

 muft abide by the opinion formerly given, refpefting their gene- 

 ral inutility. I put it to your correfpondent, whether he thinks 

 the grain raifed upon a large corn farm could be thraflied cheapefl 

 with one machine worked by fix horfes, or with fix fmall ma- 

 chines each worked by one horfe, and requiring the number of 

 hands he defcribes. This queftion brings the bufinefs into nar- 

 row bounds, and, if anfwered in favour of the large machine, 

 as I prefume mud be the cafe, fettles the difpute. In fa^l, with 

 large machines, corn is thraflied and cleaned at very little more 

 expence than is incurred by the cleaning procefs when fmall ma- 

 chines are employed ; and granting, for argument's fake, that in 

 both cafes it is equally well thraihed, flil> the faving in fhaking 

 and cleaning is an objecl: of confiderable magnitude. 



I do not think I was wi(ie of the mark w^hen I dated, that one 

 boll of grain per horfe per hour might be taken as a fair average 

 cf work performed by thralhing machines. That more may be 

 done with fliort oats in every feafon, and with all grains in parti- 

 cular feafons, I readily admit ; but, taking feafons as they gene- 

 rally happen, and grain according to the proportions ufually raif* 

 ed over the kingdom, I mud maintain that my calculation was 

 tolerably accurate, if regular journies or yokings, not detached 

 hours, are to be edimated. But, allowing I w^as wrong, what 

 benefit does your correfpondent's argument get thereby } If more 

 is thrafhed per horfe per hour than I calculated, the advantage is 

 reciprocal. I grant it would affed my argument in fo far as it 



applied 



