When invited to give this lecture in a building overlooking London's river, my thoughts wandered back to many pleasant hours spent in watching Nature's graceful handiwork—the common seagull, so lamiliar to those of us who still have “time to stand and stare” in these hustling days of speed arid yet more speed. Wheeling with arched pinions and webbed feet retracted backwards into auxiliary tail organs, these effortless soarers are a vision of to-morrow. What aeronautical engineer, released for a moment from the narrow confines of the drawing board and the workshop, could wish for more profitable day-dreaming than a quiet half-hour spent on London Bridge (shall we say?), admiring the cunning perfection of natural flight? And who could wish for better inspiration for the subject of this paper than a glimpse now and again at Nature's own elegant solution of the undercarriage problem?