MILLS, horse and hand, are usually upon a small construction, rarely calculated to produce any considerable effect, and more appropriate to domestic purposes of inferiorconsideration. These machines, as their names imply, derive their action from animal force, which is unquestion ably the dearest, most irregular, and least efficient, of all the powers hitherto appli ed to mechanism. In horse-mills, one, two, or more horses, or other cattle, are made either to draw, or push before them, levers, which project from a cen tre shaft, bearing the great horizontal wheel that gives motion to the more re mote parts, and which act with more or less effect, according to the length of the levers, and the number of cattle employ ed. For threshing, drawing water, grind ing, polishing, &c. such a power answers as a substitute where water is not at com mand. But, owing to the inequality of pace, and to the great propensity all ani mals have to lean towards the centre (in lieu of moving with freedom along the given circle of perambulation,) all ma chines worked by cattle invariably be come speedily deranged, and are encum bered with an excess of friction. Hand mills labour under a similar inconveni ence : though such as are regulated by fly-wheels, which occasion a great accu mulation of force, and at the same time dispose to a degree of regularity in its action, are both more efficient and more durable. Of these we have numbers,
such as chaff-cutting machines, grind stones, &c. ; indeed, the mangle may be included among this class. In several countries, the whole of the flour, meal, used by the natives, are produced by means of hand-mills ; our legislature however, considering these as drawback; on the livelihood of a very numerous class, has prohibited their use under ve ry heavy penalties. In many parts of Scotland the tenants are generally thirl ed, i. e. invariably obliged to send what ever corn they wish to grind to some particular mill ; any deviation is actiona ble. This was at one time, perhaps, necessary, for the encouragement of mil lers, when they first introduced water machinery into that kingdom ; at present it operates not only as an inconvenience, but, in many instances, as a hardship, a mounting nearly to a prohibition. The evil, however, sometimes carries its own remedy, for the tenants sell their corn to the owner of some other neighbouring mill ; and, when it is ground, buy the flour it produced: thus they evade the thirling, which binds only to the grinding of what they do not dispose of.