ON AERIAL LOCOMOTION. 315 



llight is the wandering albatross. "A bird for endurance of lliglit 

 ])robably unrivalled. Found over all i)arts of the Southern Ocean. It 

 seldom rests on the water. During storms, even the most terrific, it is 

 seen now dashing through the whirling clouds, and now serenely tloat- 

 ing, without the least observable motion of its outstretched pinions." 

 The wings of this bird extend 14 or 15 feet from end to end, and meas- 

 ure only S}y inches across the broadest part. This conformation gives 

 the bird such an extraordinary sustaining i)ower, that it is said to sleei) 

 on the wing during stormy weather, when rest on the ocean is impossi- 

 ble. Ivising high in the air, it skims slowly down, with absolutely mo- 

 tionless wiugs, till a near approach to the waves awakens it, when it 

 rises again for another rest. 



If the force cx])ended in actually sustaining along-winged bird upon 

 a wide and unyielding stratum of air, during rapid flight, is but a small 

 fraction of its strength, then nearly the whole is exerted in overcoming 

 direct forward resistance. In the pelican i-eferred- to, the area of the 

 body, at its greatest diameter, is about luO square inches ; that of the 

 pinions, 80. But as the contour of many birds during flight approxi- 

 mates nearly to Newton's solid of least resistance, by reason of this 

 form, acting liJie the sharp bows of a ship, the opposing force against 

 the wind must be reduced down to one third or fourth part ; this gives 

 one-tenth of a horse-power, or about half the strength of a man, ex- 

 ])ended during a flight of 30 miles per hour. Judging from the action 

 of the living bird when captured, it does not appear to be more power- 

 ful than here stated. 



The transverse area of a carrier pigeon during flight (including the 

 outstretched wings) a little exceeds the ratio of 12 square inches for 

 each pound, and the wing surface, or sustaining area, 90 square inches 

 per pound. 



Experiments have been made to test the resisting power of conical 

 bodies of various forms, in the following manner : A thin lath was 

 jdaced horizontally, so as to move freely on a ])ivot set midway; at one 

 end of the lath a circular card was attached, at the other end a sliding 

 clip traversed, for holding paper cones, having their bases the exact 

 size of the opposite disk. The instrument acting like a steelyard ; and 

 when held against the wind, the pai)er cones were adjusted at different 

 distances from the center, according to their forms and angles, in order 

 to balance the resistance of the air against the opposing flat surface. 

 The resistance was found to be diminished nearly in the ratio that the 

 height of the cone exceeded the diameter of its base. 



It might be expected that the i)ull of the string of a flying kite 

 should give some indication of the force of inclined surfaces acting 

 against a current of air ; but no correct data can be obtained in this 

 way. The incline of a kite is far greater than ever appears in the case 

 of the advancing wing surface of a bird. The tail is purposely made 

 to. give steadiness by a strong pull backwards from the action of the 



