420 POLAR PROBLEMS 



of the dirigible for exploration.^ During the World War it was used 

 by the Germans for long flights, including one to East Africa, and by 

 the Italians, in cooperation with the navy, especially in the defense 

 against submarines. The main reason for the superiority of the diri- 

 gible over the airplane as a means of observation lies in the fact that, 

 while the latter can stay in the air only dynamically, the former stays 

 in the air by its buoyancy. 



The dirigible can reduce its own speed without being obliged to 

 land ; it can also reduce its speed until it comes to a complete stop ; and, 

 provided the atmosphere is calm enough, it can stand still at a certain 

 height above the ground through the use of a landing ballast buoy. 



The airplane has not the same freedom. It is obliged to keep 

 itself in movement to get the lift from its speed ; and this speed cannot 

 vary very much. Nor can the airplane stand still in the air. 



It is a fact that when there is the possibility of reducing the speed 

 at one's pleasure the observation and exploration of the ground under- 

 neath are much easier. It is easier, also, to explore the depth of the 

 sea from a dirigible than from an airplane. 



As to scientific observations, the conditions for the instruments 

 and for the personnel are much more favorable on a dirigible than on 

 an airplane. This is true not only because of the possibility of carry- 

 ing more weight, which is one of the advantages of the lighter over 

 the heavier-than-air machines, but also because the perturbation of 

 the instruments caused by the motion of the aircraft can be reduced 

 to a minimum or entirely eliminated by reducing the speed of the 

 motors or by stopping them. 



It has been said that one of the advantages of the airplane is the 

 possibility of landing for scientific observation. That is true. But 

 landing in an unknown place is frequently impossible, and very often 

 it is not safe. A dirigible can stand at anchor, provided the atmos- 

 pheric conditions are favorable, and it is then possible to land per- 

 sonnel and materials in perfect safety. A mechanism for this purpose 

 has been studied and perfected by us, but we had no opportunity to 

 use it on our transpolar flight. 



Finally, there is another attribute of the dirigible: its capacity 

 to carry a useful load much greater than that of any airplane or hy- 

 droplane, and as a rule for greater distances on a non-stop flight. So 

 far as our present knowledge goes, it would be possible to build an 



1 On the use of the airship in Arctic exploration see also especially: 



Das Luftschiff als Forschungsmittel in der Arktis: Eine Denkschrift, Internatl. Studiengesell. zur 

 Erforschung der Arktis mit dem Luftschiff, Berlin, 1924. 



Walther Bruns: Praktische Wege fiir den Einsatz des Luftschiffs grossen Typs zu ausgedehnter 

 wissenschaftlicher Erforschung und standiger Uberwachung der Arktis, in "Internatl. Studiengesell. 

 zur Erforschung der Arktis mit dem Luftschiff: Verhandl. der i. Ordentl. Versammlung in Berlin, 

 9.-13. Nov. 1926," Ergdnsungsheft No. igi zu Petermanns Mill., Gotha, I927> PP. 19-25. 



W. Bleistein: Das Starrluftschiff und seine Entwicklungsmoglichkeit fiir Weltverkehr und For- 

 schungsarbeit, ibid., pp. 89-102. — Edit. Note. 



