72 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



DEVELOPMENT OF ELECTRICITY BY FRICTION. 



It has been observed that the friction of certain granulated 

 metals on the walls of a glass vessel containing bisulphide 

 of carbon excites electricity. Silver, iron, aluminium, etc., 

 produce the phenomenon, while platinum, copper, and zinc 

 seem to be inactive. The mode of conducting the experi- 

 ment is as follows: About half an ounce of granulated silver 

 is put into a retort of thick white glass, containing an ounce 

 of pure bisulphide of carbon ; the vessel is then tightly closed 

 and shaken for some time in the dark. Sparks soon become 

 visible in the liquid, and after a while the entire mass becomes 

 luminous. If water is poured upon the outside of the vessel 

 the light immediately disappears, but it is again excited by 

 shaking. The electricity in the glass is positive. Silver 

 furnishes the best experiment. 19 (7, xiv. 



CAUSE OF THE VARIATION OF THE MAGNETIC POLE. 



The precise cause of the variation of the magnetic pole of 

 the earth has not been well established ; but in the view of 

 Dr. Menzzer this is owing to the continued variation of the 

 level of the earth's surface mainly in the polar regions. He 

 goes through a very elaborate mathematical investigation of 

 the relation between the land areas of the north and the 

 magnetic currents, and endeavors to show that with unchang- 

 ing outlines this pole will be constant, but that with any 

 variation it will necessarily be altered in its position. In the 

 fact that the level of the land is continually altering, not only 

 in the north, but elsewhere on the surface of the globe, very 

 few portions being entirely free from change, he finds the ex- 

 planation of the deflection of the needle first on one side and 

 then on the other, these changes being not all in one direc- 

 tion, the elevation of the land in one place to some extent 

 balancing its depression in another. 7 C,Feb., 1872, 127. 



NEW THEORY OF TERRESTRIAL MAGNETISM. 



Professor Zollner proposes a new theory in regard to the 

 origin of terrestrial magnetism. He adopts the idea of drift 

 currents upon the liquid surface of the sun, by means of which 

 he tries to explain the movement of the sun spots. These 

 drift currents originate, according to his conception, from the 



