240 



Calcium-carbide at Niagara, 228. 

 Capacity of a circuit, 118, 119. 

 Caustic soda, 221. 

 Chinese, magnetic needle, 21. 

 Chlorine and sodium, 219. 

 Circuit-breaker at Niagara, 199. 

 Closed circuit and current, 122. 

 Coherer (wireless telegraphy), 179. 

 Columbus, compass variations, 22, 34. 

 Condenser in resistance-coil, 118. 



in Morse relays, 131. 

 Conductors and non-conductors of electricity, 47. 



relation to electric light, 50. 



different resistances, 74, 83. 

 Cooke, needle telegraph, 108. 

 Crookes, Prof., X-ray, 121. 

 Cuneus and the Leyden jar, 8. 

 Curiosities, Ch. XX, 171. 



Daniell battery, 85. 



Differential magnet, 115. 



Dinocares and the loadstone, 20. 



Dolbear, Amos E., wireless telegraphy, 178. 



Dupay discovers positive and negative electricity, 



8. 



Duplex telegraphy, 114. 

 Dynamo-electric machines, 67. 



invented by Faraday, 14, 69. 



usual construction, 70. 



at Niagara, 192. 

 Double transmission, 115. 



Earth electric currents, in telegraphy, 99, 116, 182. 

 Earth magnetism, 32. 



effects of, on iron, 35. 

 Aurora, 35. 

 telegraph-lines, 36. 

 from sun's heat, 75. 



