The Flight Of Birds

Mr. y. W. Brearey read the other day bef ore the London Aeronautical Bóciety a paper on the action of the pectoral muscle in the flight of a bird. Expcriments in artificial fliglit, be said should reduce their theories to a demcnstrable form. It liad often been stated, for itistance, that ths power exerted by a bird in ita iiight bad been greatly exagaerated, but no one bad hitherto proved bis assertion. it, was capable, bowevcr, of satisf actory prooi by deraonstrating artiflcially ibeaction of the pectoral inusele, by the aid of which weigbt became an accessory to power. When tlie bird committed itself to the air the upward pressure in the wings stretched the elastic ligament, wbich f ormed part of the muscle, to such an extent as to allow thebird's gilding upon tne air without any exertion. The weigbt of the blrd was the mensure of tl:is elasticity. Itwassaid by sorne that at least the bird must possess the power by the down wardstrok e of the wing to waise ita own weigbt. Bnt Mr. Brearey said thatthis was not an absolute necessity, becau.se Ihe rcaction of this elastic ligament aided the force of the down stroke. He proceeded to verify his assertion by the action of a model, with wings of four feet spread, under which he íau viiauíieu nu uiuhuu uoiu iassiug iinrlcr the. body of the model. Upon jommittal to the air this just allowed of the wings being expanded, so that the model would gliae downward. He then detached the cord and wound up his power, calling attention to the f act that he had wound the indiarubber alrands thirty-two times. He showed, however, ihat although this was suflicient to créate a vigorous flapping of the wing when held in the hand, yet wheii committed to the air it had not the power to give onedownward stroke, and therefore it could only glide as before. Holding it again with the cord attached and the power wound up the same number of times, he showed that it was unable to flap the wing, becauso the two forcea were exactly held in equilibrium. There was a third factor wanted before it coulcl fly-and that weight. The model being liberated, flight was well sustained, and upon being set free several times without being wouud up any f urther, it appeared able to fly wiíh a very weak power. The same thing was observable with another model, composed entirely of a loóse surface thrown inte a wave acion - his own inventiou. Mr. Brearey emarked that this economy in flight eau only be obtained by something of the nature of wiug action, and must be wholly wantiug in any apparatus aetuated by the screw.