Two trials of Zeppelin’s second air ship were made on the Borden-See, one on November 30, 1906, the other on January 17, 1907; but both met with serious accident. In the first trial the balloon was towed by a motor boat some distance, then cut loose in the wind, which was carrying it forward faster than the boat. But it soon became unmanageable and plunged into the water, suffering considerable damage. In the second trial it flew for a short time at a speed of thirty feet per second, when the engines were developing 36 horse power. Some maneuvering was effected in a strong wind, but presently the propellers stopped, the vessel dropped to the shore and was anchored on the ground. During the night it was so badly damaged by the wind that Count Zeppelin ordered it to be taken to pieces to furnish material for further construction.
The loss of two mammoth air ships after such brief trial seemed enough to appall even a sturdy general of the Prussian army; but Count Zeppelin was too resolute to waste time in futile tears and hopeless dejection. Strong natures are usually stimulated by disaster, and aroused to fuller energy, to grimmer determination, if not to desperate hazard. However, not desperation, but buoyant hope and high expectation, based on ample experience, were now his ruling motive. Had not his ship attained thirty feet per second with less than one fourth her motive power? The year began with disaster indeed, but he intended it to terminate in glorious victory. And such, indeed, was the happy issue.
October, 1907, witnessed the launching of Zeppelin III. She had the same length as her immediate predecessor, but she was a luckier vessel and better powered. On her official trial she voyaged at the height of half a mile, carrying eleven persons sixty-seven miles in two hours and seventeen minutes, or at more than twenty-nine miles per hour. This was a record velocity exceeding that of the best military balloon in France. At times she attained a velocity of fifty feet per second, thus considerably outspeeding the swiftest ocean liner. Moreover, her stability and steering qualities were excellent. With pardonable elation, therefore, the illustrious inventor could report to the Minister of War the complete success of his experiments. And with good reason the German government now granted financial aid to test more fully the merits of the rigid system of construction.
With this assistance the industrious aëronaut erected a new floating house on the Borden-See at Friedrichshafen, and began the construction of a still larger air ship embodying further improvements in various details. Zeppelin IV was 446 feet long, 42.5 in diameter, held 460,000 cubic feet of hydrogen in her sixteen compartments, and had a total buoyancy of sixteen tons. She had a surplus buoyancy of over two tons, carried a crew of 18 men, and had an estimated range of action of eighteen hundred miles. When drawn from her shed in the autumn of 1907, her great buoyant hull resting lightly on the water supported by her two floating cars, she had all the appearance of a royal passenger express ready for important service. In general features the vessel was like her three predecessors, but in the center of the keel, with transparent floors and windowed sides, was a special stateroom designed for passengers only. This seemed very suggestive, if not prophetic, of the future trend of aërial navigation. Moreover, the mechanism of propulsion and control were increased in power and effectiveness. In each boat-like car was a 110-horse-power Daimler benzine engine, actuating a pair of three-blade propellers about 15 feet in diameter. A large vertical rudder, mounted on the extreme end of the stern, and supplemented by a pair of smaller vertical rudders at either side of the stern, served to steer the vessel right and left. For steering up and down, as also for exerting a direct lift up or down, four superposed planes like a Venetian blind were placed at either side of the hull fore and aft, at about the same level as the propellers. In addition the hull was provided, like a feathered arrow, with fixed fin-like planes at the stern, both vertical and horizontal, for securing steadiness of flight.
Several trials of this leviathan were made preliminary to her official government test which, if satisfactory, assured her purchase by the German government for $500,000. At the builder’s suggestion this test should include a voyage of 24 hours duration, a safe descent on land or water, an ascent to 4,000 feet, and the fulfillment of various secret requirements. In the autumn of 1907 a successful voyage of eight hours was easily accomplished. In the early part of the next summer, 1908, a series of voyages were made which aroused intense interest throughout the civilized world. On June 13th the great ship, starting from her harbor at Friedrichshafen, sailed over the Alps to Lucerne, steering in among the mountains; here buffeted by eddies, and cross currents, there stemming such stiff head winds that her shadow could hardly creep forward over the ground, again driving through a dark lowering hailstorm which pelted with ominous thunder on her resounding hull; but at length reaching Lucerne safely, then returning in triumph to her harbor at Friedrichshafen. For twelve hours the stanch vessel endured the elements, by no means hospitable, and in that period voyaged 270 miles at an average speed of 22 miles an hour. It was a record journey and a triumph in the art.
The following picturesque account of a flight in Count von Zeppelin’s gigantic air ship, written by Emil Sandt, appeared in the Scientific American Supplement of August 15, 1908:
“Early in the morning Professor Hergesell, Freiherr von Bassus, Dr. Stalberg, Herr Uhland, and myself set out in Count Zeppelin’s launch for the shed in which the great air ship is housed. When we arrived everything was in readiness for us. Count Zeppelin is proud of the fact that his colossal craft can be drawn in and out of the shed with very little help. In seven minutes the huge gas bag had emerged, and a few minutes later we were floating up to the sky. I took my station in the central car or cabin, a comfortable room flooded with the yellow light that filters through the translucent balloon fabric of which the walls, the floor and the ceiling are constituted. Comfortable seats suspended from fine chains provide a seating capacity for a dozen passengers.
“For a great portion of their length the walls are provided with celluloid panes. The floor is also transparent wherever it is not used as a footway. Seated comfortably in the central car, I could look down through my knees and see the green earth, water, people, cities and castles far below. I could also see birds circling around and fluttering anxiously, evidently frightened by the strange giant of the air.
“We crossed over to the Ueberlinger See, traversed the intermediate neck of land, and turned into the valley of the Rhine at Konstanz. Here I left the central car and walked toward the rear car along the keelway, which is flanked with balloon cloth, and which is closed at the end of the keelway by a celluloid door. I opened the door and stepped out on the narrow aluminum gangway, which runs down sharply to the rear car. The gangway has no protecting handrail. It is merely ribbed to give a better foothold. That apparently flimsy structure bridges a chasm of twenty feet between the end of the keelway and the car. From below, the passage from the keelway and the car must seem perilous indeed, but up in the air ship itself no fear is felt. I stood on this narrow bridge and gazed on the landscape. To the north I could see the Hohendtwiel. Behind us lay the Swabian See glistening in the morning’s sun. In the southeast I saw Thurgau wrapped in violet light. On the horizon the lofty peak of the Saentis rose broad and jagged, capped with ice and snow. Below us writhed the Rhine. I looked across at the propellers. Count von Zeppelin had signaled full speed ahead. The giant air ship trembled. The propellers seemed like disks, revolving with furious speed and yet as transparent as a locust’s wings. They gave out a note like that of a deep organ, so loud that the human voice, even when lifted to a shriek, could hardly be heard.
“I walked down to the rear car to obtain a better view. Here the gigantic craft could be seen in a wonderful perspective. The sensation was strange. The giant ship obediently sank and rose. Obediently moved to the right or to the left, slavishly following the slightest pressure of the human hand. Sometimes its angle was such that the entire fabric seemed inclined like a kite. At times the forward car lay below us; at times we had to look up at it.
“As we neared the splendid falls of the Rhine at Schaffhausen, the Count brought the air ship down, in order to ascertain whether the eddies occasioned by the waterfall would have any effect.
“We turned into the Reusstal, but were buffeted by the wind all the way up the valley. To the south the sharp jutting peak of Mount Pilatus hove in sight. Soon Lucerne appeared, a jewel among cities. The lake itself shimmered brightly where it was struck by the sun; its darker portions lay like an emerald, held in a setting of heliotrope. It was like a melody in colors. Below us in Lucerne itself there was a hubbub and a great jubilation. The streets were crowded with gayly clad people. The roads were a-swarm. Zeppelin guided his air ship down, and allowed it to glide full speed over the city at the height of a church steeple.
“We traveled over the Vierwaldstaetter See, and crossed to Knessnacht, to Zug Lake, and up northward to Zug itself. Then came the most difficult task which Professor Hergesell had assigned to the air ship. The craft was to carry us straight across to Lake Zurich, through a narrow pass where it would be caught in a veritable cyclone. The motors groaned and rattled. The propellers howled a deep groaning song. The air ship did all that it could. The wind was dead against us, traveling with a velocity of nearly thirty-one miles an hour. The Count could easily have arisen and escaped the fury of the blast, but it was his purpose not to avoid obstacles, but to court them. Whenever the great air ship showed signs of swerving, it was brought back to its course. Far below us in the valley the sharply marked shadow of the air ship, crawling slowly from tree to tree, showed us how hard it was struggling. There were minutes when it seemed as if we stood stock still, despite the infernal music of the propellers. Gradually the nose of the craft was thrust forward; once more the air ship mastered the winds. We had forced our way through the pass, and were dashing on at full speed. The vast shadow below us traveled with the velocity of a bird over the mountain, valleys, cliffs and rocky points, over railway embankments and road, over water and land.”
Two attempts were made in July, 1908, to complete the government test; but they proved abortive, and in the second one the hull was damaged by the wind pushing it sidewise against the shed, as it was being towed out by motor boat. This accident caused a delay of two weeks, much to the disappointment of the expectant populace. As a consequence Zeppelin resolved to begin the next attempt unheralded. He had the repairs made quickly and all was ready early in August.
On Tuesday, August 4th, at six forty-five in the morning, the great twenty-four hour test for the government began, without previous announcement, but with fairest prospect of success. Sailing from Friedrichshafen, Zeppelin purposed to follow the Rhine as far down as Mayence, then return in a direct line to his starting point. All went splendidly at first. He passed Constance at seven o’clock in the morning, Basle at nine-thirty, Strassburg about noon, then with slower speed passed Mannheim at two-fifty and Darmstadt at four-thirty. At about six o’clock a descent was made at Oppenheim, eleven and a quarter hours after starting. The air ship had voyaged 270 miles at the average speed of 22 miles an hour. A wonderful demonstration it was for the inhabitants of that historic valley, and a glorious tour for the brave old sailor and his crew. Resuming the voyage, Mayence, the turning point, was reached at eleven o’clock at night, and the vessel was headed for home. But now the engines, being overworked, could not maintain the usual speed, which therefore was lowered to twelve miles an hour. Next morning at eight o’clock, after Stuttgart had been passed, a descent had to be made at the village of Echterdingen, to adjust and overhaul the machinery. Ninety-five miles of the return had been made in nine hours.
It was most unfortunate that a landing had to be made without a harbor, particularly as a gale was in pursuit of the vessel. Ere long she was torn from her moorings by a squall, carried into the air, and set on fire, probably by an electric discharge. Immediately the great hull was enveloped in flame and completely destroyed, leaving a tangled network of distorted framing. It was a dismal termination to the greatest motor balloon voyage in the world’s history up to that date; for the vessel had been in the air continuously for twenty and three-fourths hours and had traveled 378 miles.