RADIO ATMOSPHERIC DISTURBANCES—AUSTIN 207 
It seems to be pretty well settled, in all parts of the world where 
observations have been made, that there is a very definite connection 
between the intensity of the disturbances and the position of the sun. 
In the Northern Hemisphere during the winter when the sun is far 
in the south, the disturbances are generally moderate even as far 
south as Panama, within 9° of the equator. But as the sun comes 
north in the spring, there is often a rapid and, sometimes, very 
sudden increase in strength, and it is reported that stations close to 
the Iquator experience two disturbance maxima, corresponding to 
the two periods when the sun is nearly overhead. 
In addition to the study of the sources of the disturbances, the 
question of their wave form is of much importance. Messrs. ‘Watt 
and Appleton* in England, working under the Radio Research 
Board, have made some investigations of this problem, making use 
of the cathode-ray oscillograph (Braun tube). In their work the 
atmospheric disturbance, after being received on an aperiodic 
antenna and amplified by an aperiodic resistance-coupled amplifier, 
was impressed on one pair of plates of the oscillograph, while a 
source of 60-cycle current was connected to the other pair of plates 
for the purpose of drawing out the spot of light into a line on the 
fluorescent screen. The resulting movement of the spot of light 
could not be photographed, but could be observed and sketched 
with some accuracy. Five typical curves are shown in the figures. 
Most of these appear to be aperiodic, though some are feebly 
oscillatory. 
In Figure 3 it is seen that there are minute oscillations superposed 
on the main curve. It will be noted that the period of main oscilla- 
tion is, in all cases, of audio frequency; and Eckersley ** has pointed 
out recently that the relatively prolonged impulses of Watt and Ap- 
pleton can not account for the observed intensity of the atmos- 
pherics, ordinarily experienced in radio reception. He suggests that 
possibly the ripples, such as are shown in Figure 38, may be the actual 
atmospheric waves. Mr. Watt in the symposium cited accepts this 
view and adds that more recent experiments in Egypt and elsewhere 
in the Tropics show that there the fine ripple structure is much more 
common and of much greater amplitude than in England. Profes- 
sor Appleton, on the other hand, holds that the low-frequency wave 
forms shown in the figures are capable of producing the observed dis- 
turbances at all wave lengths by shock excitation. 
In conclusion, the differences of opinion mentioned in this paper 
show that there is still much to be done before the sources of the 
disturbances are identified with certainty. While many of the at- 
45 Proc. Roy. Soe., A, 103: 84. 1923. 
16 Wleetrician (London), 93: 150. 1924. 
