smaller kites, lie would succeed in obtaining a successful form for a flying machine.
There are two ways in which Mabel II. might be towed—on wheels along a track or on floats on the surface of a lake. Dr. Bell preferred to try the second method first, as it is simpler and easier.
With tetrahedral frames he built three long boats and covered them with oilcloth to make them watertight. The boats possess great strength, and yet, because of their tetrahedral structure, are so light as not to overweight the kite. 
Fig. 14. Testing one of the Boats of Mabel. II. The three boats were then ranged parallel to one another and the whole structure placed upon and securely fastened to them.
Fig. 15 shows Mabel II., just before she was launched. This figure and Figs. 16 and 17 give an excellent idea of the construction of the kite. Across the floats extend two bridges, built of tetrahedral cells. Resting on the bridges are four large kites, like the one shown in Fig. 8. The spaces between the four kites are filled with smaller tetrahedral cells. In all there are 272 cells in the structure.
Fig, 18 shows the kite floating merrily on the water waiting to be put to the test. With her tiers of red wings above and white wings below she was a beautiful sight. But would she fly? A small model of Mabel II., shown in Fig. 13 had flown beautifully on land. The flying weight of this model was greater than the flying weight of Mabel II., and Dr. Bell had therefore every reason to believe that Mabel II. would also fly if he could raise her.
When everything was ready Mabel II. was towed out to the center of the bay and her flying line cast aboard the steamer which Dr. Bell had engaged for the experiment. The flying line was made fast to a cleat on deck and the steamer started ahead at full speed, twelve or thirteen knots an hour.
But Mabel II. was working under two bad handicaps—first, a
