THE POPULAR SCIENCE MONTHLY.
Fig. 3. A. A Winged Tetrahedral 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