=51. Pottery Knobs.=—=Door knobs=, which are important appurtenances to locks and latches, are made of many kinds of materials, and are fastened to the spindle in several ways. It is necessary, in order to make the proper selection of knobs for doors, to be thoroughly conversant with the various types on the market. The cheapest type of door knob is molded from several kinds of clay. These =pottery knobs= are secured to iron or bronze shanks by _leading_; that is, by setting them in molten lead, which, in hardening, secures the knob to the shank. [Illustration: FIG. 58] Pottery knobs are made in three styles, namely, _mineral_, _jet_, and _porcelain_. Mineral knobs are dark brown in color, while jet and porcelain knobs are, respectively, jet black and pure white. All of these knobs are highly glazed, and are used only with the cheapest grades of locks. Ordinarily, they are furnished with japanned mountings, or shank and rose; occasionally, however, they may be had with bronze-plated, real bronze, or brass mountings. The several styles of porcelain knobs are illustrated in Fig. 58. At (_a_) is shown the mineral knob, while at (_b_) and (_c_) are shown the porcelain and jet kinds. =52. Wooden Knobs.=—Knobs made of wood are quite generally used. They are always turned from some hardwood, and are either stained or finished naturally. The wooden knob is usually forced on the shank by hydraulic pressure, and when securely fastened in this way makes a desirable and cheap knob. Many of the cheaper wooden knobs on the market are only glued or cemented to the shank, and, consequently, are not durable, as they pull off; they are therefore entirely undesirable. The mountings for the better knobs are made of iron, brass, or bronze, though they may be had with wooden roses. Mountings of wood, however, should not be used, as any severe side strain on the knob will split the rose with the grain of the wood. In Fig. 59 are shown two wooden knobs, the one at (_a_) having a metal rose, and the one at (_b_) a wooden rose. =53. Cast-Iron Knobs.= Cheap locks are usually provided with knobs made of cast-iron, and, although they are strong and serviceable, they are seldom attractive. For finishing knobs of this kind, a bronze metal plating is usually employed. Cast-iron knobs are frequently made ornamental instead of plain. A typical cast-iron knob and rose are shown in Fig. 60. [Illustration: FIG. 59] [Illustration: FIG. 60] =54. Stamped and Spun-Metal Knobs.=—Knobs made of sheet metal have lately come into extensive use, and they may be obtained in a large variety of designs and forms. Plain and ornamental steel knobs are illustrated in Fig. 61. Knobs ornamented in any style of design are in the market, and are artistic and usually well modeled. [Illustration: FIG. 61]