CONTEMPORARY ADVANCES IN PHYSICS 



167 



ceived by the influence of temperature on the fibres, MilHkan and 

 Bowen compared the divergence of these when the balloon had 

 reached a certain height (it was five kilometres) on the upward way, 

 with their divergence as the apparatus passed the same level in de- 

 scending. During the time while it was above this level, the fibres of 



Fig. 8 — Records obtained by automatic registration at high altitudes by Millikan 

 and Bowen (somewhat retouched). 



the electroscope lost three times the charge that would have leaked 

 away, if the instrument had been left on the ground. This again is 

 proof that the cosmic rays are stronger in the upper air than in the 

 lower. 



As I remarked above, until last year it had been deemed beyond the 

 powers of living man to soar to heights so great as fifteen kilometres. 

 This opinion was confuted by the superbly audacious flight of the 

 Belgian physicist Piccard, which everyone will remember who reads 

 the papers, though other things than cosmic rays were stressed in their 

 accounts. Piccard seemingly has not yet published a full nor any 

 extensive story of his measurements on cosmic rays, not at any rate 

 in the physical journals; but in the bulletin of the French Physical 

 Society I find an item in which he states as provisional result — awaiting 

 further calibration of his instruments — that the ionization at a height 



