Meantime, owing to the success of the "L-I" in cross-country operations, another and more powerful craft, the "L-II" had been taken in hand, and this was constructed also for naval use. While shorter than her consort, being only 487 feet over all, this vessel had a greater beam--55 feet. This latter increase was decided because it was conceded to be an easier matter to provide for greater beam than enhanced length in the existing air-ship harbours. The "L-II" displaced 27 tons--five tons in excess of her predecessor. In this vessel many innovations were introduced, such as the provision of the passage-way connecting the cars within the hull, instead of outside the latter as had hitherto been the practice, while the three cars were placed more closely together than formerly. The motors were of an improved type, giving an aggregate output of 900 horse-power, and were divided into four separate units, housed in two engine-rooms, the front car being a replica in every detail of the navigating bridge of a warship. This vessel was regarded as a distinct improvement upon the "L-I," although the latter could boast some great achievements. But her glory was short-lived. In the course of the Government trials, while some 900 feet aloft, the huge vessel suddenly exploded and was burned in the air, a mass of broken and twisted metal-work falling to the ground. Of the 28 officers and men, including members of the Admiralty Board who were conducting the official trials, all but one were killed outright, and the solitary exception was so terribly burned as to survive the fall for only a few hours. The accident was remarkable and demonstrated very convincingly that although Count Zeppelin apparently had made huge strides in aerial navigation through the passage of years, yet in reality he had made no progress at all. He committed the identical error that characterised the effort of Severo Pax ten years previously, and the disaster was directly attributable to the self-same cause as that which overwhelmed the Severo airship. The gas, escaping from the balloons housed in the hull, collected in the confined passage-way communicating with the cars, came into contact with a naked light, possibly the exhaust from the motors, and instantly detonated with terrific force, blowing the airship to fragments and setting fire to all the inflammable materials.