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[[image]] George Hodgkings of Setauket, N. Y., amounted to $200,000, the income from one-half of which is devoted to "the increase and diffusion of more exact knowledge in regard to the nature and properties of atmospheric air in connection with the welfare of man." The object of this fund has been interpreted very broadly. Flight of Birds and Insects. To discover the secret of flight of birds and insects is a purpose to which a portion of the income of the Hodgkins fund has been devoted. It is an object touching directly upon human progress. The fund, therefore, lends material support to experiments which may mean the ultimate extension of man's control over an element hitherto unconquered. The present grant to Dr. von Lendenfeld is for the special purpose, as Secretary Wal- inve on of the organs of flight of the best representative flyers of the insect order. In this investigation the wings of insects are to be considered in relation to the mechanics of flight as well as from a purely morphological point of view." This research follows naturally upon conclusions which Dr. von Lendenfeld has already reached in work conducted personally and under his direction for a number of years Two reports have been published by the Smithsonian Institution and two more are now in press to appear as regular issues of the Smithsonian miscellaneous collections. Dr. von Lendenfeld's first work under a Smithsonian grant was performed in 1900. It consisted mainly of general studies into the structure and functions of the organs of flying creatures as a preparation suitable for researches into the actual mechanics of flight. Since then much of his time has been taken up in personal laboratory investigations or in directing investigations of his pupils in the university at Prague. The first set of experiments, completed about three years ago, brought out some curious facts concerning the wings of birds in relation to the weight of their bodies. It was established beyond a doubt that some property of air enabled the larger and heavier birds, such as the albatross and eagle, to sustain their weight with comparatively much smaller wing surface. It was worked out by analogy that, given the secret of control of motion, a man weighing 200 pounds (90 kilograms) could sail through the air with a sustaining wing surface of about three square yards (2.7 square mters). All Do Not Fly Alike. But when Dr. von Lendenfeld turned to consider the actual mechanics of flight he was confronted immediately by the fact that all birds by no means fly alike. In fact, there could hardly be established a mean similarity between all the varieties. From the great soaring albatross and sea eagle, which may sail for half an hour without the quiver of a feather, to the whirring sparrow and the buzzing humming bird, which rely for support solely upon the rapid movement of their wings, there is a long line of flyers. These two extremes, the albatross and the humming bird, the experimenter took as types. Insects, also, he found could be classed in a like manner. Among both birds and insects, however, the sailers were found not to be restricted to the large creatures and the flappers to the small. On the contrary, there were discovered creatures of all sizes in each group. In the sailer class the lemon butterfly was placed beside the stork and the silver gull beside the dragon fly. The flapper class embraced flyers from the buzzard and pheasant to the house fly and the gnat. In this study of flight method, therefore, the question of size led to no conclusions. Muscular power was an element to be considered. Dr. von Lendenfeld was satisfied that the flappers were gifted with much stronger muscles than the sailers. And merely for illustrative purposes, since he does not consider the feasibility of attaching wings to man, he found that, although a human being could not immediately develop enough muscle to join the flapper class, he might well be able, if he knew how, to soar at will. All these conclusions hinged upon the interesting phenomenon that the increase in weight to be carried through the air is not proportional to the necessary increase in size supporting the surface-that is, the larger the bird the smaller the proportion are the wings. The results can be explained "only upon the supposition that the resistance of the air against moving wings is not directly proportional to their size, but that in enlarging the wings the resisting power of the air against them increases in a greater ratio than their superficial dimensions. Knowing that the air requires an appreciable time to yield to the pressure of the moving wing, and the larger the wing surface the greater the quantity of air displaced and the greater the resistance of this compressed air to the subse wing stroke which must act upon it, ow would destroy it, Mr. led: "Mr. Peary is a king ork, but his knowledge of must be limited. He does erhaps, that the envelope tensile strength of 500 the square foot. I would he snow which could harm falling on this envelope .000 versato. e Depositi in: | A nbre, 5 agliano, 17 ROMA Viale Castro Bretorio, 92, 94° Viale della Regina, 142C FIRENZE Piazza Vittorio Emanuele Via Castellani E Ottobre PADOVA PISA [[image]] azzeni ed Auto-Garage in TORINO - Corso Re Umberto, 62-64, angolo
