The stability of these aërial monsters is attained by the use of large projecting fins. Horizontal steering is effected by a large central rudder and pairs of double vertical planes riveted between the fixed horizontal stability planes. For vertical steering there are sixteen planes provided in sets of four on each side of the front and rear ends of the balloons. These can be independently inclined upwards or downwards. When the forward ones are inclined upwards and the after planes downwards, the reaction of the air on the planes as the airship is driven forwards causes the front part to rise and the rear part to sink, and the airship is propelled in an inclined direction to a higher level. The favourite housing place for the Zeppelin airships has in the past been on Lake Constance, near Friedrichshafen, so that they could be taken out under protection from the direction of the wind. It is also much safer for large airships to make their descent over the surface of water. It has been estimated that the most powerful Zeppelins have a speed of some fifty miles an hour. When on April 3rd, 1913, Z 16, in the course of a journey from Friedrichshafen, was forced to descend on French soil at Lunéville, excellent opportunity was afforded the French of a close inspection of its details. The following were the exact dimensions, etc.:-- Length 140 metres Diameter 15 metres Cubic capacity 20,000 metres Motive power three Maybach motors, 170 h.p. each 510 h.p. Speed 22 metres per sec. Height attainable 2,200 metres Useful carrying power 7,000 kilos. On the top of the ship was a platform, on which a mitrailleuse could be mounted. It was only a few weeks before the present war that the new Zeppelin, L Z 24, attained a new world’s record of altitude and duration of flight. The height attained was 3,125 metres. The voyage without a break lasted thirty-four hours fifty-nine minutes. On May 22nd, 1914, it left Friedrichshafen at 7.16 a.m. Bâle was reached at 10 a.m. At 6 p.m. it passed Frankfort, at 9 Metz, at 10.30 Bingen, at 2 a.m. Brême. At 4 a.m. it arrived above Heligoland, from whence it made for Potsdam, where it was hailed 9.20 a.m. At 5.15 p.m. it landed at Johannisthal. That journey certainly showed the long-range powers of the latest Zeppelins. If, as will be seen, it is comparatively easy for a few well-directed aëroplanes to wreck them in mid-air, still they have ceased to be military or naval playthings.