HELIUM. THE NEW BALLOON GAS 



445 



Official photograph, U. S. Naval Air Service 



RESCUING AN AVIATOR FROM ONE OF THE FLORIDA KEYS 



To demonstrate the ease and accuracy with which its dirigibles can be navigated, the crew 

 of one of the L T . S. Navy's airships "marooned" one of their number on an island and sailed 

 away. After a brief cruise, the dirigible was brought back and its rope ladder dropped over- 

 board, within reach of the aviator who had been left behind. In the photograph the rescued 

 man is seen climbing arbft as their airship resumes its journey. 



might contain argon 



\ccordingly, he 

 extracted some of the gas for himself; 

 but he, too, was mistaken, for it proved 

 to be not argon, but the element helium, 

 which Lockver had seen in the sun so 



long before. 



After that, oddly enough, it was only 

 a year or so before various other chem- 

 ists detected helium in the atmosphere, 

 in the gas given off by mineral springs, 

 and in the volcanic fumes of Vesuvius. 



Xone of these gases, however, contain 

 more than a fraction of one per cent of 

 helium — the atmosphere itself contains 

 only four ten-thousandths of one per 

 cent — and although helium was thus 

 found to be widely distributed, it was 

 always regarded as one of the rare ele- 

 ments. 



Although the discovery of helium in 

 natural gas has proved to be a great boon 

 to the United States, it was a rather sor- 



