112 Trans. Acad. Sci. of St. Louis 
ing the aurora of June 20th, although a spot was observed near the 
west limb on July 7th. It could hardly have been responsible for 
the second aurora because it passed the central meridian after the 
aurora, whereas, to have caused it, the spot should have passed the 
central meridian shortly before the aurora. The display of June 
id come, however, 21 days after the ending of the aurora of 
May 29th and 30th, which time is just a little less than the period 
of the sun’s rotation. The area of disturbance observed before 
May 29th would again have been near the central meridian about 
une 20th. erefore, the same area may have been responsible 
for both auroras. 
Conclusions. 
Although the observed solar activity was not pronounced, the 
coincidence in time between the auroral display of May 29th and 
30th, 1932, and the hydrogen activity near a sun-spot observed just 
before the display, justify our conclusions that a real relation 
existed between the two. This seems more probable because of the 
appearance of a second aurora after an interval of time nearly equal 
to the period of the sun’s rotation. In the foregoing observations, 
therefore, we have an instance in which a particular atmospheric 
and magnetic disturbance on the earth was preceded by a definite 
solar disturbance. This is further evidence of the direct relation- 
ship between solar and terrestrial phenomena, and of the influence 
that cosmic disturbances have upon the earth. 
Literature Cited. 
Angot, Alfred. The Aurora Borealis. New York, 1897. 
Birkeland, Kr. -On the Cause of Magnetic Storms and the Origin 
of Terrestrial Magnetism (The Norwegian Aurora Polaris Expedi- 
tion, 1902-1903, Vol. I, Part II), transl. by Miss Jessie Muir. Chris- 
tiania, Norway, 1913. 
Hale, G. E. Signals from the Stars. New York, 1931. 
Kennelly, A. E. Cosmic Disturbances of the Earth’s Magnetic 
Field and their Influence upon Radio Communication. Scientific 
Monthly, XXXV, No. 1: 42-56. July, 1932. 
