4 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 7I 



geocoronium sphere. This highest sphere appears to consist essen- 

 tially of ait element, " geocoronium," a gas undiscovered at the sur- 

 face of the earth, having a spectrum which is the single aurora line, 

 557/X|ti, and being 0.4 as heavy as hydrogen. The existence of such a 

 gas is in agreement with Nicholson's theory of the atom, and its 

 investigation would, of course, be a matter of considerable importance 

 to astronomy and physics as well as to meteorology. It is of interest, 

 to note that the greatest altitude attained by sounding balloons 

 extends but one-third through the second region, or stratosphere. 



No instruments for obtaining data at these high altitudes are herein 

 discussed, but it will be at once evident that their construction is a 

 problem of small difficulty compared with the attainment of the 

 desired altitudes. 



