. Animal flight; a record of observation . Outline of outer part of a wing of an adjutant when in metacarpal descent. A. Line on prolongation ofwhich is centre of effortof cambered part of thewing. B. Line on prolongation ofwhich is centre of liftingeffort of phalangeal quills. metacarpal descent, it has changed from a mode offlight in which it takes energy from the air to a modeof flight in which it no longer takes energy from theair. The only known change in the disposition of thewings is the retire-ment of the wing-tips. If the wing nolonger takes energyfrom the air it isdifficult to imagin
. Animal flight; a record of observation . Outline of outer part of a wing of an adjutant when in metacarpal descent. A. Line on prolongation ofwhich is centre of effortof cambered part of thewing. B. Line on prolongation ofwhich is centre of liftingeffort of phalangeal quills. metacarpal descent, it has changed from a mode offlight in which it takes energy from the air to a modeof flight in which it no longer takes energy from theair. The only known change in the disposition of thewings is the retire-ment of the wing-tips. If the wing nolonger takes energyfrom the air it isdifficult to imaginethat its angle of in-cidence is the same. A. Dotted line indicates junc-tion of secondary andmetacarpal quills. B. C. Indicates junction of meta-carpal and digital of alula. as before. As may be observed, the angle of incidenceis certainly not increased. It is therefore probable thatretirement of the wing-tip either facilitates, or moreprobably causes, a decrease of the angle of incidence. 132 ANIMAL FLIGHT. When descending in a strong wind another modeof descent may be adopted. Flexing of the wings isincreased to a greater extent than that usual in fastflex-gliding. The bird accordingly drops through theair feet foremost with the flexed wings extended hori-zontally. The alula is usually advanced. This mode ofdescending may be termed carpal descent. At theend of a metacarpal descent, when speed has sufficientlydiminished, there is often a change to carpal descentby further flexure of the wings. I shall describe casesof carpal descent in detail on a later occasion. The smaller birds frequently C^)descend by a me
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