 In more concrete terms, the sounding of the Manchester factory hooters, plus the absence of whatever conditions would make them sound when it wasn’t five o’clock, plus the presence of whatever conditions are, along with its being five o’clock, jointly sufficient for the Londoners to stop work a moment later—including, say, automatic devices for setting off the London hooters at five o’clock, is a conjunction of features which is unconditionally followed by the Londoners stopping work. (1974: 84)