As I wish that my experience may be of benefit to the reader, even in its failures, I will add that I made the not unnatural mistake of building on the plan on which the hull of an ordinary ship is constructed; that is, making the hull support the projecting bowsprit and other parts. In the aerodrome, what corresponds to the bowsprit must project far in advance of the hull to sustain the front wings, and a like piece must project behind it to sustain the rear wings and the tail, or the supporting surfaces of whatever kind. The mistake of the construction lay in disjoining these two and connecting them indirectly by the insufficiently strong hull which supported them. This hull was formed of longitudinal U-shaped ribs of thin steel, which rested on rings made of an alloy of aluminum, which possessed the lightness of the latter metal with very considerable toughness, but which was finally unsatisfactory. I may say parenthetically that in none of the subsequent constructions has the lightness of aluminum been found to compensate for its very many disadvantages. The two rods, which were each 1 metre in length, were with difficulty kept rigorously in line, owing to the yielding of the constructionally weak hull. It would have been better, in fact, to have carried the rod straight through at any inconvenience to the disposition of the boilers and the engine. [Illustration: PL. 10 STEEL FRAMES OF AERODROMES NOS. 0, 1, 2, 3, 1891 AND 1892] I may add that the sustaining surfaces, which were to be nearly flat wings, composed of silk stretched from a steel tube with wooden attachments, were to [p033] have been carried on the front rod, but, as subsequent experience has shown, these wings would have been inadequate to the work, both from their insufficient size and their lack of rigidity. The propellers, which were to be 80 cm. in diameter, 1.25 pitch-ratio, and which were expected to make from five to six hundred revolutions a minute, were carried on the end of long tubular shafts, not parallel, but making with each other an angle of 25 degrees, and united by gears near the bow of the vessel in the manner shown in Plate 10.