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POPULAR SCIENCE MONTHLY 



Fig. 3. A. A Winged Tetrahedkal Cell. 

 C. A Sixteen-celled Tetrahedral Kite. 



The Method of Building up Kites with Tetrahedral Cells. The four-celled kite 

 B weighs four times as much as one cell and has four times as much wing-surface ; the sixteen- 

 celled kite Chas sixteen times as much weight and sixteen times as much wing-surface; and 

 the sixty-four celled kite D has sixty-four times as much weight and sixty-four times as much 



the efficiency nor the size of a kite could be increased by using many 

 small Hargrave box cells instead of two large box cells. 



The problem was then to invent a new cell, one that could be used 

 in combination. Circular cells, polygonal cells of six, eight and 



