NICKING—was formerly considered an OPERATION of much MAGNITUDE, and not without its proportion of _danger_; and then performed only by such as were considered eminent in the PRACTICE, and expert in the ART. It is now, however, a matter of so little consequence, that anatomical knowledge is not thought at all necessary to the execution; it being a well-known fact, that almost every DEALER (or even his principal servant) is an operator from one extremity of the kingdom to the other. The intent of NICKING is to prevent (by a counteracting power) a horse from depressing his TAIL, and flicking it between his hind quarters; giving him all the appearance of perpetual fear, and constitutional dejection. A horse of this description is held in very trifling estimation, and purchasers are not readily to be found till this operation has been gone through, and the _good_ or _bad_ set of the TAIL ascertained, upon the ornamental part of which, both the figure and proportional value of the subject greatly depend. This operation, as it was formerly performed, indeed as it is _now_ by common FARRIERS and inexperienced GROOMS, appears one of the most cruel and severe that could possibly originate in the human mind; though in the hands of those well acquainted with the STRUCTURE of the PARTS, having a quick eye, and steady execution, it is a matter so superficial, and attended with so little pain or difficulty, that it does not seem entitled to even serious consideration. In order that the process, and proper use of NICKING, may be the better comprehended by the younger branches of the SPORTING WORLD who have never seen it performed, it becomes directly applicable to observe, that there are in every limb of either the human or brute creation, two sets of muscles, acting in a contrary direction to the other. The office of one is to EXPAND; the other, to CONTRACT: the former are technically termed the EXTENSOR; the latter, the FLEXOR muscles: thus, then, it is, that the _extensors_ possess the power of extending or straightening the limb; the _flexors_, of relaxing and completely bending it. Of these two sets, the flexors have the greater predominance, and can always overcome the resisting property of their opposites; but when, by an effort of the will, the extensors are brought into forcible action, then overcoming the little resistence that is either made or felt: of this force in the flexor muscles, ample proof may be obtained, by endeavouring to raise the TAIL of an _unnicked_ horse against his will.