INSTRUMENTS OF HUSBANDRY. 89 



In regard to horse machines, Mr Brown of Markle cal- 

 culates, that a six-horse machine will, in two days per week, 

 thresh the produce of 600 Scotch or 762 English acres, 

 whatever the nature of the grain may be ; but if the crops 

 are either oats or barley, or the wheat straw short, the 

 produce of 700 Scotch, or 890 English acres, may be 

 threshed, and dressed for market, by such a machine. 



It is observed, that where threshing-machines are wrought 

 by horses, and only the same number of horses kept as 

 before the erection of the mill, it will be necessary to give 

 the work-hordes hay instead of straw; as the mill generally 

 occasions additional labour to the horses, perhaps for five 

 months in winter, to the amount of from, one-sixth to one- 

 eighth more. 



Threshing-mills, having the drum or cylinder driven by 

 a strap, were constructed by a Mr Cotterel on Leith Walk, 

 about the year 1788, or 1790; but in a few years, they dis- 

 appeared, as will others of the same construction, a strap 

 being found inefficient to drive the nave of a threshing- 

 mill. 



On the whole, the remarks made by Mr Kerr, on these 

 various powers, seem to be just. The greatest objection 

 to horse machines, he observes, is the severity of labour 

 which they require, besides often necessarily occupying 

 the time of the farm-horses, when much wanted for other 

 purposes. The capital defect of the threshing-mills which 

 are driven by wind, is the extreme uncertainty of that 

 power. During the long-continued frosts of winter, when 

 there is hardly any wind, they are often altogether useless 

 for weeks, when straw for litter and fodder cannot be dis- 

 pensed with ; and the same thing sometimes happens du- 

 ring harvest, when straw is much wanted for thatch, * 



* Wind-mills also, are sometimes apt to have their arms broken by 



