2 20 The National Geographic Magazine 



Of course in other respects the two 



cases are not identical. A kite sustained 

 by a 20-mile breeze possesses no mo- 

 mentum, or rather its momentum is 

 equal to zero, because it is stationary in 

 the air and has no motion proper of its 

 own; but the momentum of a heavy 

 body propelled at 20 miles an hour 

 through still air is very considerable. 

 Momentum certainly aids flight, and it 

 may even be a source of support against 

 gravity quite independently of the press- 

 ure of the air. It is perfectly possible, 

 therefore, that an apparatus may prove 

 to be efficient as a flying-machine which 

 cannot be flown as a kite on account of 

 the absence of vis viva. 



However this may be, the applicabil- 

 ity of kite experiments to the flying- 

 machine problem has for a long time 

 past been the guiding thought in my 

 researches. 



I have not cared to ascertain how high 

 a kite may be flown or to make one fly 

 at any very great altitude. The point 

 I have had specially in mind is this: 

 That the equilibrium of the structure in 

 the air should be perfect; that the kite 

 should fly steadily, and not move about 

 from side to side or dive suddenly when 

 struck by a squall, and that when re- 

 leased it should drop slowly and gently 

 to the ground without material oscilla- 

 tion. I have also considered it impor- 

 tant that the framework should possess 

 great strength with little weight. 



I believe that in the form of structure 

 now attained the properties of strength, 

 lightness, and steady flight have been 

 united in a remarkable degree. 



In my younger days the word ' ' kite ' ' 

 suggested a structure of wood in the 

 form of a cross covered with paper form- 

 ing a diamond-shaped surface longer 

 one way than the other, and provided 

 with a long tail composed of a string 

 with numerous pieces of paper tied at 

 intervals upon it. Such a kite is simply 

 a toy. In Europe and America, where 

 kites of this type prevailed, kite-flying 

 was pursued only as an amusement for 



children, and the improvement of the 

 form of structure was hardly considered 

 a suitable subject of thought for a scien- 

 tific man. 



In Asia kite-flying has been for cen- 

 turies the amusement of adults, and the 

 Chinese, Japanese, and Malays have 

 developed tailless kites very much supe- 

 rior to any form of kite known to us 

 until quite recently. 



It is only within the last few years 

 that improvements in kite structure 

 have been seriously considered, and the 

 recent developments in the art have been 

 largely due to the efforts of one man — 

 Mr Laurence Hargrave, of Australia. 



Hargrave realized that the structure 

 best adapted for what is called a ' ' good 

 kite ' ' would also be suitable as the basis 

 for the structure of a flying-machine. 

 His researches, published by the Royal 

 Societ3' of New South Wales, have at- 

 tracted the attention of the world, and 

 form the starting point for modern re- 

 searches upon the subject in Europe 

 and America. 



Anything relating to aerial locomotion 

 has an interest to very nian3' minds, and 

 scientific kite-flying has everywhere 

 been stimulated by Hargrave's experi- 

 ments. 



In America, however, the chief stim- 

 ulus to scientific kite-flying has been the 

 fact developed by the United States 

 Weather 'Bureau, that important infor- 

 mation could be obtained concerning 

 weather conditions if kites could be con- 

 structed capable of lifting meteorological 

 instruments to a great elevation in the 

 free air. Mr Eddy and others in Amer- 

 ica have taken the Malay tailless kite 

 as a basis for their experiments, but 

 Professor Marvin, of the United States 

 Weather Bureau ; Mr Rotch, of the Blue 

 Hill Observatory, and many others have 

 adapted Hargrave's box kite for the 

 purpose. 



Congress has made appropriations to 

 the Weather Bureau in aid of its kite 

 experiments, and a number of meteoro- 

 logical stations throughout the United 



