Waterbury evening Democrat., 1893-04-21
TIE FLIGHT OF BIRDS.
The so- Called Horizontal Motion Is Really
 Undulating.

The So-Called Horizontal MotIo1 Is Really
 Undulating.
 Navigation of the air is a leading problem of the age, and in spite of the practical difficulties remaining unsur- mounted there is confidence that mans inventive genius can devise some plan of conquering the domain of the earth's atmosphere. An explanation of the mechanics of bird-fiight clearly points to the conclusion that aerial navigation depends for it's satisfactory solution on application of the same principles Flight involves wing surfaces (pres- sure-surfaccs) which must be both large and light For example, a body weigh ing one hundred and fifty pounds will require approximately twelve square yards of wing-surface. The wing-sur- faces of birds are supporting-surfaces, lifting-surfaces, and relatively, gliding surfaces. These wing-surfaces are ap- proximately about enc two-hundredths of the weight of the bird The down. stroke of the wing is rapid and resist ing, the up-stroke slower. There re- suits a.quicl< lift, and as the upper sur face is very smooth and gently arched, the up-stroke meets with less resist ance. From the effect of the down o0LohS pOSSIOAAAty Ok the lifting power. drawing of bent bow shows the wing position with the action suspended during flight. As the wing-surface from the beginning to the end of the stroke makes shovel shaped or scooping movement, scooping the air from above forward, and strik- ing it downward and backward, by which the wing-surfaces describe jet hn ySc identical with. part of a crew stroke there results combina- tion of two operations, a raising and a forward pushing movement, which constitute together one operation of flight: CD The so-callcd horizontal flight is not actually in stra ght line, but is undulating. Supposing the bird rises from the ground, he holds his body obliquely, and rises in an oblong course by rapid strokes of the wing. On reach ing desired height he brings his body to the horizontal direction by means of his steering appliances, and pursues his horizontal course, accelerated by the influence of gravitation. The bird is continuously subject to this force, which it overeomes with every stroke of the wing, and the quicker the operation the more rapidly the bird shoots for ward For an intelligent horizontal flight the steering appliances of the bird are, however, of frst-class impor- tance. These are the head, the neck and the tail, and, if the last is wanting, the outstretched legs. These together balance the body for horizontal flight @ Linear horizontal sailing without beating of the wings is only the contin- uous motion following powerful wing strokes which give the body forward impulse, in which it is supported by stiff, outstretched wings gliding over the volume of air which presses upward | against it. The direction of sailing is only apparently horizontal, and persists only so long as the force of propulsion overcomes the force of gravitation. The bird must then renew his stroke or he will glide gradually downward. If a bird floats a considerable distance with out beating his wings or descending, it is in consequence of resisting current From such simple principles is gradual | ly being worked out the problem of air navigation. A dirigible flying machine, it is thought by many scientists, can be constructed, provided of course, there be an intelligent application of the flight | generating force of rationally construct ed pressure-surfaces.- Y. Ledger.