138 POPULAR SCIENCE MONTHLY. 



Fourtli. — By the use of the tetrahedral cell it is possible to build 

 kites unlimited in size and in which, however gigantic the kite, the 

 ratio of supporting surface to weight remains the same as in a small 

 kite. 



The successive doubling in size of the kite shown in Fig, 3 may be 

 carried on indefinitely without the weight increasing faster than the 

 wing surface. The cells all act in harmony; no part of a kite built of 

 tetrahedral cells has to be strengthened to counterbalance an opposing 

 force or a weakness in some other part of the kite; no weight is thrown 

 away. 



By his invention of the regular tetrahedral winged cell, Dr. Bell 

 thus got around the old law which said you can build kites up to a 



Fig. 6. SixTY-FOUK Cellkd Kite composed of Four of Preceding. ' Red Fi.ier.' 



certain size, but no greater. The adherents of that law have always 

 admitted that the law might be circumvented if a kite could be com- 

 bined of many small models, but they have denied or at least doubted 

 that a working combination of small models effective enough to carry 

 a man, and to be called a flying machine, could be made. With his 

 tetrahedral cell Dr. Bell has, however, been able to build kites of 

 tremendous power, strong enough to carry up several men. One of his 

 first kites lifted two men off their feet in a squall, and they only 

 saved themselves from an undesirable ascent by instantly dropping the 

 rope. Later this same kite (Fig. 4) snapped its rope, a three-eighth- 

 inch new manila rope, as quickly as a thread. Kites much more power- 



