=26. Sizes of Hinge Butts.=—The standard hinge butts are always square, but they may be procured in irregular sizes, at additional cost. In indicating the size of irregular hinge butts—that is, the butts that are not square, and that are consequently not standard—two dimensions must always be given. The first dimension stated should indicate the height of the butt, and the second the width of the butt when it is open. Thus, a 6" × 5" butt is 6 inches high and 5 inches wide when opened. This rule for indicating the size of hinge butts is easy to remember, from the fact that it is the reverse of that ordinarily employed by builders when indicating the sizes of doors and windows, for here it is customary to give the horizontal dimension first and the height of the opening last. [Illustration: FIG. 19] =27. Single-Acting Hinges, or Butts.=—There is a large butt, or hinge, in the market that has a coil spring either between the knuckles, or enclosed between the leaves. This device is known as the =single-acting hinge=, and is illustrated in Fig. 19. At (_a_) is shown the _Bommer single-acting hinge_, which has a spiral spring enclosed within the casing formed by one of the knuckles. The tension on this spring can be increased by operating the collar at _a_ with a pin, or bar. At (_b_) is shown a single-acting spring hinge known as the _Chicago single-acting spring butt_. This hinge butt has a spiral spring that is encased between two leaves. In operating, this spring always tends to throw the door back to its closed position. These two kinds of single-acting hinges are used more than any other hinge of the same nature now in the market, but for doors of large size the liquid door check is preferred, although it is more costly. Single-acting hinge butts are used principally for hanging water-closet slat doors; and they are also used for light doors that do not reach the full height of the opening, and which have no jambs. The Bommer hinge, as shown in Fig. 19 (_a_), has an advantage on account of the simple means provided for adjusting the tension of the coil, or spring, by which the momentum of the door in swinging to and fro can be reduced to a minimum, thus shutting the door with little noise as it strikes the stop. [Illustration: FIG. 20] Two other types of the Bommer single-acting spring hinge are shown in Fig. 20. At (_a_) are shown two types of single-acting, surface, spring hinges that are used for lavatory doors, while at (_b_) is shown a similar single-acting spring hinge arranged for securing to a marble or slate stile or partition. These hinges are commonly supplied in highly polished nickel plate, brass, or bronze. The clamp hinge illustrated at (_b_) is made to secure to slabs of marble or slate from 1 to 2 inches in thickness, advancing by quarter inches. This type of hinge is also adjustable ⅛ inch over and under the stated sizes. [Illustration: FIG. 21]