110 Trans, Acad. Sci. of St. Louis — 
ning she saw a faint arch of light extending across the northern 
sky, cutting the horizon at two points a little less than 180° apart. 
After 10:30 p. m., the display became much brighter, and indistinct 
shafts of light, apparently radiating from a point below the horizon, 
appeared through waves of light that moved like ripples and looked 
like smoke lighted from below and coming from the north. At this 
time there was no definite arch. Weak colors were exhibited, prin- 
cipally rosy-pink. 
Observations in Washington and Jefferson Counties, 
Missouri. 
Miss Dorothy Boyer, of Kimmswick, Missouri, observed a wide 
ribbon of light extending obliquely from the west toward Polaris, 
at about midnight on the night of May 30, 1932, while motoring 
from Washington County, Missouri, into Jefferson County. A little 
after 1:45 a. m., the northern border of the ribbon became edged 
with pink, and sulphur-colored lights alternating with salmon-pink 
shafts appeared. These faded out shortly, leaving the sky glowing 
in a lively manner, but colorless. This display was probably the 
end of the aurora that began the day before, and is therefore further 
evidence of its magnitude. 
Observations at Valley Park, Missouri, on June 20, 1932. 
Miss Nellie Matlock and party, of St. Louis, Missouri, observed 
an aurora on the night of June 20, 1932, near Valley Park, Mis- 
souri. This display was described as being comparable to the moon 
in brilliance. A n r of rays were seen, although no mention 
ca : 
to Angot (loc. cit., p. 36), bluish-lavender is rather rare in auroras. 
Discussion. 
The causes of auroral activity are not yet entirely understood, 
although it has been well established that sun-spots, terrestrial mag- 
netism, and auroras are related phenomena. records of sun- 
spot numbers, magnetic disturbances on the earth, and auroral ac- 
tivity have shown that when sun-spots are numerous, the frequency 
and intensity of both auroras and magnetic storms are greater, and 
that great auroras are always accompanied by magnetic storms. 
Birkeland (1913) projected cathode rays into the field of a mag- 
netized iron ball placed in a glass box in which the air was under 
very low pressure, and by varying the strength of the magnetic field 
of the ball, the intensity of the cathode rays, and the pressure, he 
was able to reproduce certain features of the aurora and other phe- 
