=83. Door Stops and Holders.=—Since door checks and double-acting doors have come into more extensive use, the necessity of holding doors open has created a demand for _door stops_ and _holders_. The =door stop= is a device for limiting the backward swing of a door. This device may also be constructed so as to perform the additional function of holding the door in an open position; it is then known as a =door holder=. [Illustration: FIG. 103] The ordinary door stop is simply a wooden knob with rubber tip, or ring, that may be fastened to the floor or a baseboard, and is usually made up in the forms shown in Fig. 103. Better grades made of iron or bronze are also available. These come in various shapes, as shown in Fig. 104. Frequently, as shown at _a_, a hook for fastening the door in an open position is combined with the door stop. [Illustration: FIG. 104] [Illustration: FIG. 105] The door stop with the hook holdback is not always convenient to use, so that the _automatic holdback_, or _door holder_ shown in Fig. 105 is sometimes employed. This holder can be disengaged by a pull on the handle of the door and automatically catches the door in an entire open position. Where it is desired to hold a door in any position or to release it quickly, the rubber-tipped holder shown in Fig. 106 should be used; this device is easily operated and controlled by the foot. [Illustration: FIG. 106] [Illustration: FIG. 107] =84. Chain Door Fastener.=—The type of =chain fastener= illustrated in Fig. 107 is generally used on exterior residence doors. This device allows the occupants to open the door partly without permitting entrance. It consists of a heavy chain, one end of which is attached to a plate, which in turn is fastened to the jamb with screws. The other end of the chain carries a ball or a hook that may be inserted in the slot of the long plate, which is attached to the door. By this means, the door may be opened only slightly, until the ball of the chain is released from the slot. [Illustration: FIG. 108] [Illustration: FIG. 109] =85. Door Bolts.=—A large variety of =door bolts= is now on the market. These bolts are made in all sizes, in wrought steel, cast iron, brass, and bronze, and may be procured in any finish desired. The several types of bolts used in common practice are illustrated in Figs. 108 and 109. In Fig. 108 (_a_) is shown a type of _barrel bolt_; at (_b_) is shown what is known as a _cased bolt_; and at (_c_) is shown a _necked bolt_. Fig. 109 (_a_) shows a _spring bolt_, (_b_) a _spring-necked bolt_, and (_c_) a type of _shutter bolt_. Various types of _mortise bolts_ are illustrated in Fig. 110. [Illustration: FIG. 110] [Illustration: FIG. 111] [Illustration: FIG. 112] [Illustration: FIG. 113] [Illustration: FIG. 114]