In the old tool the cutting surface was small, being rarely more than three quarters of an inch broad, and the blunt sides afforded rather a show of protection than any positive security. Mr. Gowing has increased the breadth needed to make the chisel useful, and he has also added two falling sides, that, dropping over the lateral surfaces of the molars, guide the instrument, which works as in a groove. More steadiness is thus obtained, and the operator, consequently, can act with decision. The new chisel, however, is not intended to be used alone; if singly employed, it might do some damage, and fracture almost as readily be induced as formerly. To prevent such an accident other aids were imperative, and perceiving this, the instrument, which the following wood-cut represents, was invented by Mr. Gowing. [Illustration] It is carved, so as to be suited to the shape of the horse's mouth, and at one end has a handle, while at the other is a cutting edge, between two circular guards, which prevent any injury being done to the softer parts. When a shelving projection of tooth is to be removed, this instrument is introduced into the mouth, and the sharp edge is lodged against the back of the tooth, when it is given to an assistant to hold, while the operator, taking the chisel, proceeds to employ it in the way before mentioned. The object here is two-fold. In the first place, the chisel is restrained or prevented from being urged against the posterior of the mouth by the stroke of the hammer; and in the next place, the concussion is received upon the instrument, and taken from the jaw. Sometimes when a tooth is loose, but not either of sufficient size, or fitting shape, for the application of the forceps, the sharp edge can be got to a certain degree behind, and under it, when by a wrenching action it can be either elevated or forced out. There are, however, cases in which none of the instruments hitherto described answer so well as might be wished. Frequently little pieces or sharp corners of teeth project, and to remove these, demands more variety of position on the part of the operator, than the previous instruments will admit of. To meet this difficulty, Mr. Gowing, who to the surgery of the teeth has devoted more study than any person has hitherto bestowed upon the subject, invented the instrument represented in the annexed wood-cut. [Illustration]