In order to meet the specifications drawn up by the War Department, the big airship was required to make a continuous flight of two hours under the power of the motor, and be capable of manoeuvring in any direction. Curtiss realised that in order to fill these requirements a new type motor would be needed. He designed and set about building, therefore, a water-cooled motor, something which had not been attempted at the Curtiss factory up to this time, and the success of which marked a long step in advance. Although Baldwin had built thirteen dirigibles, all of which had been equipped with motors built by Curtiss, and all of which had been operated successfully in exhibitions, the Government contract was his most ambitious undertaking. About the balloon itself, there was never any doubt; the thing that clung constantly in the minds of these men who were bending every effort to the conquest of the air, was: "Will the motor do its work in a two-hours' endurance test, and will it furnish the necessary power to drive the big airship at a speed of twenty miles an hour?" The conditions under which the trial was to be made were entirely unique. The motor had to be suspended on a light but substantial framework beneath the great gas-bag, and from this framework the pilot and the engineer had to do their work. The Army dirigible was completed on time and its test took place at Washington in the summer of 1905. Captain Baldwin acted as pilot and Curtiss as engineer. The airship met every specification and was accepted by the Government. A flight of two hours' duration was made over the wooded hills of Virginia, and this stands to-day as the longest continuous flight ever made by a dirigible airship in this country. PART II MY FIRST FLIGHTS by Glenn H. Curtiss CHAPTER I BEGINNING TO FLY In 1905, while in New York City, I first met Dr. Alexander Graham Bell, the inventor of the telephone. Dr. Bell had learned of our light-weight motors, used with success on the Baldwin dirigibles, and wanted to secure one for use in his experiments with kites. We had a very interesting talk on these experiments, and he asked me to visit him at Bienn Bhreagh, his summer home near Baddeck, Nova Scotia. Dr. Bell had developed some wonderfully light and strong tetrahedral kites which possessed great inherent stability, and he wanted a motor to install in one of them for purposes of experimentation. This kite was a very large one. The Doctor called it an "aerodrome." The surfaces not being planes, it could not properly be described as an aeroplane. He believed that the time would come when the framework of the aeroplane would have to be so large in proportion to its surface that it would be too heavy to fly. Consequently, he evolved the tetrahedral or cellular form of structure, which would allow of the size being increased indefinitely, while the weight would be increased only in the same ratio.