Page:Popular Science Monthly Volume 64.djvu/146

142 sixty-four, the cells being four times as large. The kite is not as successful as the preceding one. Dr. Bell's experiments have convinced him that the small cells are better; when the wind varies in strength as in a squall, the shifting of pressure on a small cell is less than the shifting on a large cell; hence the resultant shifting of pressure on a kite built of small cells is considerably less than on a kite built of large cells. Fig. 8 shows the method of attaching five pounds, a piece of lead in this case; the kite is not disturbed by the weight. The kite

shown in Figs. 9, 10 and 11 is also tetrahedral in form and built of tetrahedral cells. It is twice as large as the red flier, being four meters on a side. Fig. 9 gives a side view and Fig. 10 a front view of the kite as it rests on its keel. The average pull of this kite in light winds is 80 pounds; in a heavy wind it exceeds 150 pounds.

The strength of the kites made of tetrahedral cells is something remarkable. I have seen one of these kites towed on a tetrahedral float for more than a mile on the bay at a speed of eleven or twelve knots without breaking, though one end was dragging one foot under water all the time. As I saw the kite pulled along I expected to see it