CONQUEST OF TIME AND SPACE 



gas cools and the balloon settles. It was to com- 

 pensate this erratic tendency of the balloon that Mr. 

 Wellman invented his much talked of equilibrator, 

 consisting of gasoline tanks and blocks of wood ar- 

 ranged to trail in the water, and thus to add weight 

 to the balloon when it tended to rise. The equilibra- 

 tor proved a dangerous accessory, however, when it 

 encountered heavy seas. 



Mr. Vaniman, the chief engineer of Mr. Wellman's 

 illfated trip, planned a new type of equilibrator which 

 should dip up water when weight was needed and 

 empty it when not needed. But such contrivances 

 are clumsy at best, and it seems likely that the solu- 

 tion of the ballast problem must be looked for in quite 

 another direction. 



The air-chambers devised by Major Parseval (and 

 which were adopted as accessories in both the Well- 

 man and the Vaniman airships) afford at least a 

 partial solution of the problem. Mr. Briicker planned 

 to cool his airship in the daytime by spraying it. 

 Other attempts to maintain the hydrogen at even tem- 

 perature have utilized the plan of having a double- 

 coated balloon with an air-chamber surrounding the 

 gas-bag. Just before his death Vaniman attempted to 

 solve the problem from the other point of view, by 

 making the balloon-envelop strong enough to with- 

 stand the pressure of hydrogen expanding under in- 

 fluence of the sun's rays. Apparently any material 

 stout enough to resist this pressure would prove much 

 too unwieldy and heavy. But Vaniman's balloon ex- 

 ploded in its trial trip off the Jersey coast in 1912, 

 the inventor himself and his companions falling to 



291 



