Rollers.—If a door or a gate is moved by sliding, and not by turning on an axis, rollers are used, to diminish friction. Figure 31 illustrates both running- rollers and sliding rollers, the first of these terms being ap plied when the rollers are at the top, as in sliding- doors in rooms, and the second when they are at the bottom, as in doors of magazines. The lower part of Figure 31 furnishes side and sectional views of the running roller, which moves on a horizontal pin screwed between iron plates and is guided by an edge rail. The sliding roller seen in the upper part of the Figure is smaller and lighter than the running roller. It is also guided by a rail, and lies between a prolongation of two angle-irons which are fastened to the door.
The Sliding Bolt (fig. 3o) is an appliance used specially on two-leaved doors. It might probably be most appropriately classed among fastenings, as it serves to secure that one of two leaves which is not generally opened, being applied to both the upper and the lower end of the leaf. Various details are shown by the illustration. When the doors are very high, the top bolt is made long enough for the handle to be easily reached. When the bolt is heavy, a fiat spring is put between it and the plate bv which it is supported, so as to prevent its falling by its ONVII weight when driven up. On doors of rooms the bolts are generally countersunk. Figure io (pi. 8) shows a secret-spring latch for office doors, etc., and Figures 13 to 15 the ordinary thumb latch.
particularly those on balconies, often have the same fastenings as windows. Window fasten ings can be moved on the inner side only, and such movements are made without the use of a key. There are three leading varieties—namely, the turn-buckle, the espagnolett, and the bascule.
Turn-buckles may be either half buckles or whole buckles. Figure 32 (pi. 7) illustrates a half buckle—used chiefly on one-sash windows—in plan and vertical section. One end of the turn-buckle is secured by a pin, so that there may be revolving movements on a plate screwed to the framing, while the other end lies on a plate screwed down on one side only, which when the buckle is not on it stands off slightly, but is pressed down by the buckle. Instead of this plate, a wire sunk in the wood is frequently used. The whole turn-buckle (fig. 33) closes two sashes simultaneously, and is fastened so as conveniently to accomplish that object. Each pair of sashes in the window has two of these turn-buckles and two knobs; and when the mullion is movable, the division carrying the latter will also re quire sliding bolts or two half turn-buckles. Figure 7 (fil. S) is a form of catch for fastening inside window blinds or shutters, and Figure 8 is a fastening for sliding sashes.
The French Lever is a modification of the turn-buckle and forms a portion of the espagnolett fastening (p. 7, fig. 34). It is used on windows with a movable centre mullion, and affords this advantage—namely, that the shut ting or opening of both sashes is simultaneously effected above, below, and at some intermediate point, or in three places, while with the turn-buckle fastening and the movable mullion four manipulations are required to close both sashes, consisting of the movement of the whole turn-buckles and of two half turn-buckles. Two additional movements of the knobs are requisite to open the sashes to which turn-buckles are attached. The triple fasten ing is accomplished by means of a vertical rod, from to y, inch thick, secured so as to be able to revolve between the two sashes, thus coining upon the movable mullion (fig. 34c) by collar hoops or rings (fig. 34a'). This rod has solid hooks at the ends, and on some point in its length a lever which can be rotated up and down (fig. 34c). The middle fastening is effected by laying this lever over into a catch on the other sash which does not carry the movable mullion, while simultaneously the hooks on the ends of the rod engage in lock hooks, one of which is placed on the transom and the other on the wiiidow sill, or, as seen in Figure 34a, in correspond ing books screwed on at these points. In opening, the lever is first thrown up and off and the vertical rod is rotated by the lever, used as a handle, the hooked ends of the rod being disengaged by this movement.
The Basade Fastening (fig. 35) is also used on windows having a 1110V able mullion, and it too effects a fastening in three places. It is a superior form of bolt used in connection with a stop. The rods lie either upon or inside of the movable mullion, and can slip vertically up and down into striking plates or lock hooks screwed on at such points as would be selected if the espagnolett were used. The rod inay be in one or more parts. In the latter case, the two parts move in opposite directions; and all the vari ous arranzements found in bascules are intended to effect this movement in different directions simultaneously with the lifting or falling of the stop. One of the best arrangements is seen in Figure 35b Gb/. 7). The stop is moved up and down by the handle ( 35a, c), while at the same time the small cog--wheel inside is made to turn, and by eng-aging- in the cogrged ends of the two bolt-rods it forces them up or down. If the bolt rod is in one piece, it must be hook-shaped at the end, and so curved that when the window is opened the hook is drawn out of the staple, while in closing one end engages as usual and the other curved end shoots into the staple from the opposite side.