A long cylindrical tube, of sufficient stoutness to afford the requisite strength, forms the handle of this instrument, and being hollow, permits a chisel to work freely within it. Indeed the chisel would work too freely if some means were not employed to steady it, therefore a large bulb, which is filled with packing and constitutes a stuffing box, is fixed at one end, and by pressing against the shaft of the chisel prevents it from being too readily displaced; though at the same time it allows of the cutting agent being propelled, with all the force that could be desired. The bulb likewise serves another purpose, as it gives the operator a firm grasp, and prevents the danger of the hold being lost when the instrument is struck. At the opposite end of the handle there is a frame, the further part or base of which is sharp upon the inner side; within this frame the chisel plays, and by it therefore is securely guarded. When the instrument is used, the chisel is drawn back to about the extent represented in the foregoing wood-cut, and into the space thus created is introduced the projecting tooth, which consequently is encircled on every side, and both before and behind is between two cutting edges. The operator then firmly grasps the handle, and applies to it such force as he calculates will be sufficient to counteract the effect of that blow which he is about to deliver. With a hammer of adequate weight he now strikes the head of the chisel, and the tooth flies off. The operation is instantaneous, and so far it is an advantage; but beyond this is the safety which accompanies it. The softer parts cannot be wounded, for the action is strictly circumscribed in every direction, but the main principle of the invention remains to be pointed out. However great may be the force employed, no sensible jar is communicated to the jaw. The writer has held between his fingers a tooth which has been divided with this instrument at a single blow, and the shock was so trivial as to be unworthy of any notice. The concussion is received upon the guard resting against the hind part of the tooth, and beyond that annoyance which the accompanying sound may excite, the horse suffers no inconvenience. Fracture of the alveolar processes is rendered impossible, and the ease with which the instrument is applied, considerably enhances its value. It would, however, be of service only when the tooth was large, and the entire body projected above the level of the other molars. It is not unfrequent for portions of the grinders, worn into various angles, to present themselves, and to occasion very serious effects upon the health of the horse. To remove these is of no less importance than to cut off the more regular and larger substance; and Mr. Gowing has produced instruments capable of fulfilling these intentions. In the first place he has improved upon the old guarded chisel, concerning the danger and inefficiency of which, remarks have been already made. [Illustration]