The second ship was practically a semi-rigid. The envelope was over twice the capacity of the earlier ship, being of 29,000 cubic feet capacity. This envelope was attached to a keel of bamboo and steel, from which was suspended by steel cables a small car. At the after end of the keel was mounted a small rudder for the horizontal steering. For steering in the vertical plane two propellers were mounted on each side of the car, swivelling to give an upward or downward thrust. A 30 horse-power J.A.P. engine was fitted in this case. Several successful flights were carried out by this ship, of which the most noteworthy was from Cardiff to London. WILLOWS No. 3 No. 2, having been rebuilt and both enlarged and improved, became known as No. 3. The capacity of the envelope, which was composed of rubber and cotton, was increased to 32,000 cubic feet, and contained two ballonets. The gross lift amounted to about half a ton. As before, a 30 horse-power J.A.P. engine was installed, driving the swivelling propellers. These propellers were two-bladed with a diameter of 61 feet. The maximum speed was supposed to be 25 miles per hour, but it is questionable if this was ever attained. This ship flew from London to Paris, and was the first British-built airship to fly across the Channel. WILLOWS No. 4 The fourth ship constructed by this firm was completed in 1912, and was slightly smaller than the two preceding ships. The capacity of the envelope in this instance was reduced to 24,000 cubic feet, but was a much better shape, having a diameter of 20 feet, which was gradually tapered towards the stern. A different material was also used, varnished silk being tried as an experiment. The envelope was attached to a keel on which was mounted the engine, a 35 horse-power Anzani, driving two swivelling four-bladed propellers. From the keel was suspended a torpedo-shaped boat car in which a crew of two was accommodated. Originally a vertical fin and rudder were mounted at the stern end of the keel, but these were later replaced by fins on the stern of the envelope. This ship was purchased by the naval authorities, and after purchase was more or less reconstructed, but carried out little flying. At the outbreak of war she was lying deflated in the shed at Farnborough. As will be seen later, this was the envelope which was rigged to the original experimental S.S. airship in the early days of 1915, and is for this reason, if for no other, particularly interesting. WILLOWS No. 5 This ship was of similar design, but of greater capacity. The envelope, which was composed of rubber-proofed fabric, gave a volume of 50,000 cubic feet, and contained two ballonets. A 60 horsepower engine drove two swivelling propellers at an estimated speed of 38 miles per hour. She was constructed at Hendon, from where she made several short trips. MARSHALL FOX'S AIRSHIP