MODERN SCIENCE. 237 



substances (or paramagnetic) ; those which are repelled, 

 diamagnetic bodies. He determined the magnetism and 

 DIAMAGNETISM of solids, liquids, and gases ; and showed that 

 all flames are repelled when placed between the two poles of 

 the magnet. This discovery of diamagnetism was one of 

 capital importance again the key to many physical pheno- 

 mena. Soon after Ampere had made electro-magnets by 

 means of an electric current, and Faraday had PRODUCED 

 ELECTRIC CURRENTS BY means of A MAGNET, the eminent 

 German physicist SEEBECK (1822) discovered THERMO- 

 ELECTRICITY, that is, the production of electricity by heat 

 a new branch of physics which has become very extensive 

 through the investigations of Melloni, Sir William Thomson, 

 Clerk Maxwell, and others. Seebeck's discovery, it has been 

 suggested, would explain the electric currents flowing from 

 East to West round our globe the sun's heat, acting upon 

 the earth's metals, inducing the terrestrial electric current ; 

 and this explanation would also account for the direction of 

 the magnetic needle to the North, because magnetic currents 

 flow across electric currents, and therefore from South to 

 North in accordance with Oersted's experiment and Ampere's 

 rule. Since then, and in connection with the subject, the 

 periodical appearance of spots in the sun has been daily 

 observed for thirty-four years by SCHWABE (from 1826 to 

 1859), an d has been found to attain the maximum every eleven 

 years. These spots are now believed to be great hollows 

 caused by cyclones possibly electric; but whatever their 

 cause or nature, the SUN SPOTS would, according to eminent 

 scientists though their theory is strongly opposed by no 

 less an electrician than Sir W. Thomson exercise a powerful 

 ACTION UPON THE TERRESTRIAL MAGNETISM, for they are 



believed to cause auroras in both hemispheres, and magnetic 

 storms which will last for several days all over the earth. 

 This at least seemed to be the case in September, 1859, f r 

 the first time, and early in the year 1892 for the last time. 

 Thus the electric and magnetic influence of the sun, observed 

 ever since Graham noticed the shifting of the needle in 

 1722, is a phenomenon of vast importance which would 

 affect the whole earth with boundless energy. The point, 



