148 



size of die drum, is certainly amongst the most im- 

 portant. The drum should not exceed from two feet 

 eight inches to three feet. That able mechanic, Mr An- 

 drew Graj, is decidedly of opinion, that a small drum, 

 with few beaters, is preferable to the larger one with 

 a great number, the small drum making better work, 



Steam has been lately applied for the purpose of impelling 

 threshing machines, a;;d is not liable to interruptions ; but 

 there has not hitherto been iufficient experience to determine 

 its comparative advantages and disadvantages. It is said 

 that izcwt. of coals, are required to thresh cut 50 Berwick- 

 shire bolls, or 300 bushels .of wheat. It is probable, however, 

 that the alternation of heating and cooling the steam ap- 

 paratus, may occasion much loss and expence in repairing the 

 furnace and boiler ; and there is liule chance, in districts mere- 

 ly rural, of btin^ readily able to procure work-people who 

 are sufficiently conversant in steam engines, for keeping the 

 valves, leathers, and other parts of such nice machinery in 

 order. 



As to the expence of threshing, Mr Robert Ker is of opinion, 

 that all the six horses in the mill, can easily be driven by one 

 man, so that two of those in the preceding calculation may be 

 deducted, which is equal to 4 s. of the whole expence. He also j 

 thinks, that one day is sufficient for dressing 100 bolls, after 

 going through the threshing machine. On the whole, he 

 makes the following estimate of the expence of threshing and, 

 dressing 50 bolls ot wheat : 



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



Four men at 2 s. 6 d. each, c i o o 



Four women at i s. each, 040 



I.. I jz o 

 Incidents, as oil, &c. o o si 



L. i 12 3i 



which is at the rate cf 7^ J. per bo!l. 



In the wind or water machine, the exprnce of the horses is 

 saved, by which the cost per boll is reduced to less than 3 

 By means of the steam power, the cost is restored to 

 the same with ho: 



