referring now to the drawings fig1 an exterior wall w has a door opening o defined by a door frame f which is set into the wall w and includes a hinge jamb 2 a strike jamb 4 and a header 6 connecting the upper ends of the two jambs 2 and 4 the door opening o is normally closed by a door d which is supported on the hinge jamb 2 by a pair of conventional hinges 8 and also by a hinge 9 capable of transmitting pressurized air into the door d such a hinge is disclosed in u s patent application ser no 461 096 of francis c peterson filed apr 15 1974 and entitled hinge capable of transmitting pressurized air the hinges 8 and 9 are attached to the door d such that the door d swings outwardly that is to the outside of the building the strike jamb 4 has a lock keeper or strike 10 set into it opposite the side edge of the door d when the door d is closed the door d carries a mortise type lock 12 fig1 which is recessed into the side edge of the door d and includes a retractable latch bolt 14 which normally projects beyond the side edge of the door d and extends into the strike 10 when the door d is closed thereby securing the door d in its closed position the exposed face of the latch bolt 14 is beveled so that the latch bolt 14 upon contacting the strike 10 as the door d closes is cammed inwardly of course when the door d reaches its fully closed position the latch bolt 14 aligns with and projects into the.