Another type of hinge made entirely of wrought steel, and known as the _New York blind hinge_, is shown in Fig. 30. This type of hinge has a long strap that extends on the top and the bottom rail of the shutter and thus tends to prevent the blind from drooping. This strap also strengthens the shutter by relieving the mortise and tenon of the rail and stile from the strain. The New York blind hinges are made in two styles. The hinge shown at (_a_) is intended for frame buildings, while that at (_b_) is made with an offset to throw the shutter clear of a brick jamb. These hinges are ordinarily used with blind adjusters, or fasteners, and for very high blinds, a center, or auxiliary, hinge is used. [Illustration: FIG. 30] [Illustration: FIG. 31] There is another type of strap hinge similar to those just described, the butt of which consists of a pin and staple, as shown in Fig. 31. This staple is secured by driving it into wooden blocking in the brick joints. Hinges of this type are used extensively in localities where brick buildings are numerous. =31. Inside Blind, or Shutter, Hinges.=—The use of inside blinds, or shutters, is general with the better class of domestic buildings, and for hanging these shutters, three kinds of hinges are used, depending on the number of folds in the shutter and the manner in which they fold back on each other. Usually, the _butt_ and the _back flap_, as shown in Fig. 32 (_a_) and (_b_), are used. Where the shutter has three folds, however, a _knuckle butt_, as shown at (_c_), is employed. The purpose of the knuckle butt is to cause the folds to take such relative positions as will enable them, when open, to close properly into a pocket, or recess, formed in the window frame. [Illustration: FIG. 32] [Illustration: FIG. 33] [Illustration: FIG. 34] [Illustration: FIG. 35] =32. Invisible Butts, or Hinges.=—A =secret=, or =invisible, hinge=, known as the _Soss hinge_, has recently been placed on the market. This hinge, which is illustrated in Fig. 33 (_a_), consists of a semicircular plate, which is attached rigidly to the door section, and a movable semicircular plate on the jamb leaf, which telescopes the section on the door in closing. These hinges are invisible when the door is closed. The disadvantage in the use of these hinges is due to the fact that they have only one wearing joint; they are also somewhat complicated and expensive. As shown in Fig. 33 (_b_), they have no throw, or offset, and consequently the door does not clear the baseboard, or trim, in opening. The larger size of hinge has a throw of 1 inch, which is not ordinarily sufficient for doors. These hinges, however, have their use for such mill work as seats, secret jambs, drop, or folding, leaves, etc., and for this class of work are the best in the market.