These subsidiary companies are also controlled by the Directorate. They were not permitted to disintegrate during the difficult period following the war, but instead, have kept their personnel and facilities intact and are ready to continue the work which was interrupted by the terms of the treaty. They produce respectively motors, gas bags, propellers, gears, sheds and, in fact, everything pertaining to aerial navigation including airplanes, flying boats and parts. The Construction Plants The great construction plants are organized on the same principles as ship yards. Over them all is the General Director, Mr. Alfred Colsman, and Chief Engineer, Dr. Ing. Ludwig Dürr, the latter having been with Count Zeppelin since the first airship was started and to whom much of the credit must be given for the success attained. There are various departments including the planning and supervising divisions, two designing divisions (one for scientific and general design, the other for workship and drawings), the manufacturing and erecting divisions, calculating and accounting, testing and controlling, and general maintenance divisions. The research department is a separate organization. The Airship Factories In the airship factories the framework is made and erected. The envelope is prepared, passenger and engine gondolas completed and assembled along with other apparatus and instruments. The power plant is built, excepting the motors and parts of the gear work. Research work along the lines of airship development is conducted there. The original plant built at Friedrichshafen in 1910 included a double shed, workshops, offices and laboratory buildings. The shed would not accommodate ships of greater diameter than 52½feet (16 meters), so in 1914 new workshops and another shed was built, to be followed the next year by a still larger shed. [PLATE 30: The “DELAG” Passenger Zeppelin “Schwaben”, 1912. The “DELAG” Passenger Zeppelin “Schwaben”, 1910. Count Zeppelin and Doctor Eckener in the pilot car.] During 1915 and 1916 better workshops (Plate 16), offices and a larger laboratory, together with the largest wind tunnel on earth were completed, along with a low pressure chamber for testing motors, a new development as unique as it was important to the automotive science. The Hydrogen Plant The original hydrogen plant was enlarged to a capacity output of 353,100 cubic feet (10,000 cubic meters) daily, with storage facilities for 2,118,600 cubic feet (60,000 cubic meters). Since the war, the storage facilities have been reduced to 706,200 cubic feet (20,000 cubic meters) by order of the Allied Commission. Powerful Radio Station The Zeppelin wireless plant, started in 1910, has continued to develop with the science of radio and is now able to communicate with the United States. The duralumin factory is capable of meeting all Zeppelin requirements. The Great Zeppelin Hangars