The heavens above: a popular handbook of astronomy (1882)
Gillet, J. A. (Joseph Anthony), 1837-1908 · New York, Chicago, Potter, Ainsworth, & Co. · leaf 211
rage diurnal oscillation inany locality increases and decreasespretty regularly during a period ofabout eleven years. The maximumand minimum of this period ofmagnetic disturbance are found toFg- =°*- coincide with the maximum and minimum of the sun-spot period. This is shown in Fig. 206, in which… … ASTRONOMY. 191 oscillating five degrees, or even ten degrees, within an houror two. These storms are generally accompanied by an aurora,and an aurora is always accompanied by magnetic disturbance.A careful comparison of aurora observations with those of sun-spots shows an almost perfect parallelism…
Astronomy
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