INSTRUMENTS OF HUSBANDRY. 99 



wheel, threshes with uncommon ease, and very clean, and 

 with so small a drum it can thresh from 10 to 12 bolls of 

 wheat in an hour, whilst the horses are so cool, that they 

 can be watered with safety after working five hours. That 

 able mechanic, Mr Andrew Gray, 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, not being so severe on the cattle, . and less 

 straining to the machinery. Although it is obvious that a 

 drum, three feet diameter, having four beaters, must take 

 two revolutions, for one of the drum six feet diameter, with 

 eight beaters, it is evident, that the circumference of the 

 one, will move nearly at the same rate as the other, because 

 one turn of the large drum, is equal to two turns of the 

 small one, they will give therefore an equal number of 

 strokes in the same time ; but it is found by experience, 

 that the small drum threshes much cleaner, or makes bet- 

 ter work, than the larger one. The small drum is therefore 

 to be preferred ; being easier driven, it must be less severe 

 on the cattle, and by its striking the corn at a more acute 

 angle, of course strips off the grain much cleaner from tne 

 straw.* 



Another improvement is, instead of two fluted rollers, to 

 have one of them plain, but chipt cross-wise, about half an 

 inch deep in various places. This prevents the straw from 



* Mr Wood of Milrig remarks, that he has always found the moderate- 

 sized threshing-mill, if all the parts are made substantially, by far the 

 most useful, and less destructive to the animals which drive it, and suffi- 

 ciently expeditious for the purpose of any farm ; and by employing a cer. 

 tain number of day-labourers, which a farm of proper size has always at 

 command, and by employing oxen for threshing ; the horses, and the 

 men who work them, are never taken from other agricultural purposes, 

 very necessary perhaps to bo carrying on at the same time. 



