=78. Window and Shutter Operating Devices.=—The sash-operating device is provided for the purpose of controlling a number of sash in a line by one piece of mechanism. Frequently, divided sashes are arranged side by side in skylights, clearstories, and monitors. These windows are usually some distance from the floor, and the operating device must be so arranged that it can be worked conveniently. The device illustrated in Fig. 97 is known as the _Lovell window and shutter operating device_, and consists of two longitudinal sections of pipe shafting _a_ connected to cog racks _b_ at the end. These cog racks in turn engage with a cog, or wheel, shaft _c_, as indicated in the figure. Connecting arms _d_, with swivel joints at each end, are arranged between the pipe shafts and the sash. The ends connected to the sash are secured to the same by means of plates and wood screws, and the swivel joint at the other end is provided with a sleeve, or socket, that is secured to the pipe shafts with a setscrew. The commendable feature of this device is that it is operated by a straight push or pull of the arm, instead of a twist, as in some other devices on the market. When the chain, or rope, around the large chain wheel is pulled, the cog is turned, and as it engages the racks, it thrusts one pipe horizontally in one direction and the other in an opposite direction. By this means, the connecting arms to the sash approach one another and lengthen the distance between the shafting and the sash, which movement tends to push the sash open, the sash being closed by the opposite operation. By this device as much as 500 feet of sash may be operated by one wheel, or “power,” as it is called. This chain wheel, or power, may be located either in the center or at the terminals, and by careful adjustment will simultaneously close all the sashes tight against the frame. [Illustration: FIG. 97] DOOR HARDWARE AND ITS APPLICATION =79. Door Pulls.=—In Fig. 98 are illustrated two well-known types of =door pulls.= The pull shown at (_a_) consists of a handle that is usually mounted on a plate and attached to either storm or single-acting doors, although, occasionally, this type is used on double-acting doors with the word “push” or “pull” inscribed on the plate. When used on double-acting doors, the door pull has a tendency to obviate the habit of persons placing their hands on the moldings near the glass when operating the door, but is subject to the objection of inviting a pull to open the door even with the word “push” inscribed on the plate. [Illustration: FIG. 98] Door pulls are made in various metals, both in plain and ornamental design, some of the latter being very elaborate, as will be observed from Fig. 99.