The vessel was of great scientific interest, owing to the ingenuity of its design and construction. The metallic skeleton was built up from aluminium and over this was stretched the fabric of the envelope, care being observed to reduce skin friction, as well as to achieve impermeability. But it was the internal arrangement of the gas-lifting balloons which provoked the greatest concern. The hull was divided into compartments, each complete in itself, and each containing a small balloon inflated with hydrogen. It was sub-division as practised in connection with vessels ploughing the water applied to aerial craft, the purpose being somewhat the same. As a ship of the seas will keep afloat so long as a certain number of its subdivisions remain watertight, so would the Zeppelin keep aloft if a certain number of the gas compartments retained their charges of hydrogen. There were no fewer than seventeen of these gas-balloons arranged in a single line within the envelope. Beneath the hull and extending the full length of the latter was a passage which not only served as a corridor for communication between the cars, but also to receive a weight attached to a cable worked by a winch. By the movement of this weight the bow or stem of the vessel could be tilted to assist ascent and descent. The construction of the vessel subsequently proved to be the easiest and most straightforward part of the whole undertaking. There were other and more serious problems to be solved. How would such a monster craft come to earth? How could she be manipulated upon the ground? How could she be docked? Upon these three points previous experience was silent. One German inventor who likewise had dreamed big things, and had carried them into execution, paid for his temerity and ambitions with his life, while his craft was reduced to a mass of twisted and torn metal. Under these circumstances Count Zeppelin decided to carry out his flights over the waters of the Bodensee and to house his craft within a floating dock. In this manner two uncertain factors might be effectively subjugated. Another problem had been ingeniously overcome. The outer envelope presented an immense surface to the atmosphere, while temperature was certain to play an uncertain part in the behaviour of the craft. The question was to reduce to the minimum the radiation of heat and cold to the bags containing the gas. This end was achieved by leaving a slight air space between the inflated gas balloons and the inner surface of the hull.