Fig. 6

Synopsis. Simplified history, each line stands for the lineage of a part: base in black; power source in light gray; striker in dark gray; set/release mechanism dashed; spring/striker unit in gray dashed. Important events: 1: add wooden base and overhead beam, modify set/release mechanism; 2: transfer twisted cord laterally; 3: add following staffe; 4: modify frame, replace twisted cord to pivot, insert striker directly; 5: replace twisted cord by wire spring with striker board fixed to looped middle part, change set/release mechanism; 5a: lateral transfer of wire spring; 6: reduce striker board and modify middle loop of spring to yield spring/striker unit, change set/release mechanism; 7: coil spring, modify frame and set/release mechanism; 8: reduce frame to flat base, modify set/release mechanism; 9: divide spring/striker unit into separate parts; I: replace clap-bow by striker board, modify frame, change set/release mechanism; II: Hannah principle: replacement of wood and fiber by metal parts (lateral transfers not shown); IIa: Transformation of spring/striker into spring/handle unit (see ‘A part’s eye-view’ below); III: mount striker jaw, spring, and set/release mechanism on oblong wooden base; IV: Replace bait hook by treadle