Page:Popular Science Monthly Volume 64.djvu/141

Rh built in the laboratory. The experiments made with these cells have given startling results:

First.—A tetrahedral cell has astonishing strength even when composed of very light wooden sticks. As Dr. Bell has expressed it: "It is not simply braced in two directions in space like a triangle, but in three directions like a solid. If I may coin a word, it possesses 'three-dimensional' strength; not 'two-dimensional' strength like a triangle, or 'one-dimensional' strength like a rod. It is the skeleton of a solid, not of a surface or a line."

Second.—A large kite constructed of tetrahedral cells is as solid as a small one, for it is likewise self-braced in all directions.

Third.—A kite built of tetrahedral cells is an almost perfect flier; it is steady in squalls, a good 'lifter' and flysflies [sic] almost directly overhead. Tetrahedral cells when combined do not interfere with each other in the least or hurt each other's flying ability as box or triangular cells do when combined.