664 SUN SPOTS AND THEIR EFFECTS. 



of earthly power are recognized as having:, directly or indirectly, a solar 

 origin. Wind-power, water-power, steam-power, the activities of organic 

 growth, all animal energy, and the great phenomena ot changes in the crust 

 of the globe, due to the circulation of waters through the circulation of at- 

 mospheric agency, are caused by the forces of solar radiation. But if the 

 solar energy is variable, the question naturally arises, " Is that variation 

 manifested in terrestrial effects, and, if so, in what manner, and to what 

 extent?" The subject is vast and new, but the indomitable enet'gy of mod- 

 ern scientific inquiry has rapidly accumulated evidence which answers the 

 first question in the afiirmative, and gives instructive replies to the others. 

 The sun-spots, for thousand of years unknown, and for centuries after they 

 were known regarded as mere matters of curious and idle speculation, are 

 now linked indissolubly to the whole scheme of activity which we observe 

 upon earth, and of which we are ourselves a part. Even the famines by 

 which nations are periodically desolated seem to be connected with this in- 

 termittence of solar energy. The evidence upon the subject has been sum- 

 med up in an able and impressive paper contributed by Messrs. Lockyer 

 and Hunter to The Nineteenth Century, and which will be found in full in No. 

 yill. of The Popular Science Supplement. We can here do little more 

 than indicate the remarkable connections that have been disclosed between 

 the variations of solar activity and resulting terrestrial phenomena. 



1. The first coincidence was in the field of terrestrial magnetism. "A 

 freely-suspended magnet, although it points in one direction, is neverthless 

 within small limits, always in motion. Certain of these motions depend, as 

 is well known, upon the hour of the day ; but the magnet is also liable to 

 irregular, abrupt fluctuations, which cannot be connected with the diurnal 

 oscillations. While Hofarth Schwabe was engaged in delineating the sun- 

 spots, Sir Edward Sabine was conducting a series of observations with 

 regard to these spasmodic aft'ections of the needle, and he found that such 

 fluctuations are most frequent in years of high sun-spot activity." Nearly 

 a hundred years ago, Yan Swinden had suggested a periodicity in these 

 irregular magnetic movements. Gauss, Arago, Lament, and Gautier, pur- 

 sued the research, and established the existence of a cycle of magnetic 

 variation having an eleven year period, the maxima and minima agreeing 

 with the maxima and minima of sun-spot activity. Schiaparelli and Broun 

 have confirmed these results, and the latter observer concludes that, while 

 the sun-spot activity is not an exact measure of magnetic action, " each is a 

 distinct result due to the same cause." This disturbance is so great that, in 

 years of maximum sun-spots, the working of the telegraph has been power- 

 fully interfered with. 



2. Connected with tlicse effects Lhero have been observed corresponding 

 disturbances of electrical activity. A magnetic storm never rages without 

 various accompanying signs of electrical excitement. These are seen in 

 auroral displays that in their varying intensities conform to the magnetic 

 cycles. Prof I.oomis, of Yale College, after a critical study of the subject. 



