MIRACLES OF SCIENCE 



their death. It is possible that the final solution of the 

 gas-expansion problem may be found in a system of 

 refrigeration pipes, similar to those used in cold- 

 storage plants, or conversely in a system of ordinary 

 hot-air pipes operated from the engine-room. 



The most difficult problem that has confronted the 

 makers of airships since the elementry principles of 

 dirigibility were solved, has had to do not with the 

 actual flight of the ship but with the safe landing of 

 the craft. The cigar-shaped aircraft, with its thin 

 shell of silk and rubber is obviously a trail structure. 

 When not in use it must be housed in a tunnel-like 

 shed. The sheds originally made at Lake Constance 

 were stationary, and it was impossible to bring the 

 airships out except when the wind blew almost di- 

 rectly in line of the long axis of the shed. Even a mild 

 lateral wind would bring such pressure to bear as 

 probably to break the airship in two. This, indeed, is 

 precisely what happened to the British Naval airship 

 "Mayfly" when it was being towed out of its shed for 

 its maiden voyage. 



The difficulty can be met by having the shed so 

 constructed as to rotate on its axis, like a draw-bridge. 

 The alternative is to have tracks extending from the 

 mouth of the shed, on which the airship may be 

 securely anchored and thus given complete rigidity 

 before being run into the shed. 



Of course the Germans have no monopoly in the 

 building of airships. The French are close competi- 

 tors, and their newest war-balloons, particularly those 

 of the Clement-Bayard type (including the "Morning 

 Post," which was built in France and piloted across 



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