seat so as to thrust the footrest forwardly of the seat to an extended leg supporting position and to retract the footrest in turn upon the manipulation by the occupant of the hand lever 24 at the side of the chair a specific mechanism for this purpose is illustrated in u s pat no 3 869 169 issued march 4 1975 to me jointly together with henry james and assigned to the assignee of this invention it will therefore be sufficient for present purposes to note that the footrest being supported by the two extensible rails is driven forwardly and rearwardly by identical linkages at opposite sides of the chair whose movements are synchronized by a horizontal cross shaft 52 journaled in the seat frame extending from side to side of the seat at the front thereof in said u s pat no 3 869 169 and as well in the chair here shown as illustrative of the setting of the invention that shaft shown in cross section in fig1 a 1 b and 1 c is square and turns through approximately 90 u00b0 by the movement of the operating lever 24 to extend the footrest i e in the movement of the parts from their positions in fig1 a to their positions in fig1 b the sequencing lock which is the focus of the present invention takes the form of a locking link 54 which is pivotally suspended from a bracket 56 secured to the seat 16 just forwardly of the post 46 to which the backrest is pivoted.