96 INSTRUMENTS OF HUSBANDRY. 



opinion, that the aggregate advantage derived from a well- 

 constructed threshing-mill, wrought by water, and under 

 proper management, (when compared with the old mode of 

 threshing), will be about 8 per cent, upon the corn thresh- 

 ed, including labour alone, but without making any allow- 

 ance for money sunk in erecting the mill, or repairing the 

 machinery. It is calculated by an intelligent fanner, that 

 a threshing-mill saves, on an average, the expence of three 

 men for nine months, which, on a farm producing, 1000 

 bolls, is equal to about L. 70, or 1 s. 3 d. per boll. Mr 

 Dudgeon, Prora, has made a comparative estimate of the 

 expence of threshing wheat by the mill and the flail ; from 

 which it appears, that the saving of charges in threshing 

 alone, independent of other advantages, though the work 

 be performed by horses, and not by any cheaper power, is 

 equal to 4<7 s. per 50 bolls, or lid. per boll, increasing with 

 the prices of grain. Mr Robert Kerr gives the following 

 estimate of the expence of threshing and dressing 50 bolls 

 of wheat : 



Three pair of horses, at 6 s. per pair, - L.O 18 

 Four men, at 2 s. 6 d. each, 010 



Four women, at 1 s. each, - 4 



L.I 12 



Incidents, as oil, &c. - - - - 003^ 



L.1 12 3 

 Which is at the rate of 7| d. per boll. 



In the wind or water-machine, the expence of the horses 

 is saved, by which the cost per boll is reduced to less than 

 3|d. By means of the steam power, the cost is restored to 

 nearly the same with horses. 



