Abstract
LONDON Aëronautical Society, July 17.—A paper, upon the action of the pectoral muscle in the flight of a bird, was read by Mr. Fred. W. Brearey. He said that it behoved all experimenters in flight to reduce their theories into a demonstrable form. It had often been stated for instance that the power exerted by a bird in its flight had been greatly exaggerated, but no one had hitherto proved his assertion. It was capable however of satisfactory proof by demonstrating artificially the action of the pectoral muscle, by the aid of which weight became an accessory to power. When the bird committed itself to the air the upward pressure in the wings stretched the elastic ligament, which formed part of the muscle, to such an extent as to allow of the bird gliding upon the air without any exertion. The weight of the bird was the measure of this elasticity. It was said by some that at least the bird must possess the power by the downward stroke of the wing to raise its own weight. But Mr. Brearey said that this was not an absolute necessity, because the reaction 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 had attached an elastic cord passing under the body of the model. Upon committal to the air this just allowed of the wings being expanded, so that the model would glide downwards. He then detached the cord and wound up his power, calling attention to the fact that he had wound the india-rubber strands thirty-two times. He showed however that although this was sufficient to create a vigorous flapping of the wing when held in the hand, yet when committed to the air it had not the power to give one downward 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, because the two forces were exactly held in equilibrium. There was a third factor wanted before it could fly—and that was weight. The model being liberated, flight was well sustained, and upon being set free several times without being wound up any further, it appeared able to fly with a very weak power. The same thing was observable with another model, composed entirely of a loose surface thrown into a wave action—his own invention. Mr. Brearey remarked that this economy in flight can only be obtained by something of the nature of wing action, and must be wholly wanting in any apparatus actuated by the screw.
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Societies and Academies . Nature 26, 335–336 (1882). https://doi.org/10.1038/026335b0
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DOI: https://doi.org/10.1038/026335b0