INDEX. 



Acetylene gas at Niagara, 230. 

 Alexandria, temple with loadstone, 20. 

 Amber elektron, 6. 

 Ampere, theory of magnetism, 25. 



unit of electriqal current, 85. 



galvanometer, 93. 

 Aluminum at Niagara, 223. 

 Arabians, magnetic needle, 21. 

 Arago, germ of electromagnet, 93. 



tie mentions torpedo, 6. 



refers to magnet, 20. 

 Atmospheric electricity, Ch. VIII, 77. 

 Atoms and molecules, 39. 



of substances differ in weight, 42. 



relations to heat, 42. 

 Aurora Borealis, 35. 



I'.ain chemical telegraph register, 101. 

 Barlow on galvanism in telegraphy, 93. 

 Bell, Alexander Graham, radiophone, 171. 

 Bleaching -powdor at Niagara, 218. 

 I '.r; i iily invents the coherer, 179. 



Cables, submarine. See Submarine Cables. 



