. Animal locomotion or walking, swimming, and flying : with a dissertation on aëronautics. 52. In this fig. // represent the moveable fulcra furnished bythe air; p p the power residing in the wing, and b the bodyto be flown. In order to make the problem of flight moreintelligible, I have prolonged the lever formed by the wingbeyond the body (b), and have applied to the root of the wingso extended the weight w iv. x represents the universaljoint by which the wing is attached to the body. When thewing ascends, as shown atp, the air (= fulcrum/) resists itsupward passage, and forces the body (b),
. Animal locomotion or walking, swimming, and flying : with a dissertation on aëronautics. 52. In this fig. // represent the moveable fulcra furnished bythe air; p p the power residing in the wing, and b the bodyto be flown. In order to make the problem of flight moreintelligible, I have prolonged the lever formed by the wingbeyond the body (b), and have applied to the root of the wingso extended the weight w iv. x represents the universaljoint by which the wing is attached to the body. When thewing ascends, as shown atp, the air (= fulcrum/) resists itsupward passage, and forces the body (b), or its representative(?r), slightly downwards. When the wing descends, as shownat p, the air (= fulcrum /) resists its downward passage,and forces the body (b), or its representative (w)f slightlyupwards. From this it follows, that when the wing rises the PROGRESSION IX OR THROUGH THE AIR. 105 body falls, and vice versa; the wing describing the arc of alarge circle (//), the body (b), or the weights representing it(w iv) describing the arc of a much smaller circle. The body, V \/>. A / w I w Fig. 52. therefore, as well as the wing, rises and falls in flight. Whenthe wing descends it elevates the body, the wing being activeand the body passive; when the body descends it elevatesthe wing, the body being active and the wing passive. Theelevator muscles, and the reaction of the air on the undersurface of the wing, contribute to its elevation. It is in thismanner that weight forms a factor in flight, the wing and theweight of the body reciprocating and mutually assisting andrelieving each other. This is an argument for employingfour wings in artificial flight, the wings being so arrrangedthat the two which are up shall always by their fall mechani-cally elevate the two which are down. Such an arrangementis calculated greatly to conserve the driving power, and, as aconsequence, to reduce the weight. It is the upper or dorsalsurface of the wing which more especially operates upon
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