CABLE IX THE HOLD OF THE 



THE ELECTRIC TELEGRAPH. 



CHAPTEE II. 



36. Common plate battery. 37. Combination of currents. 38. Loss of 

 intensity by imperfect conduction. 39. Cylindrical batteries. 40. 

 Pairs, elements, and poles denned. 41. Origin of term voltaic pile, 

 42. Use of sand in charging batteries. 43. To vary intensity of current. 

 44. Batteries used for English telegraphs. 45. Amalgamating the 

 zinc plates. 46. The line-wires, material and thickness. 47. Objection 

 to iron wires. 48. Manner of carrying' wires on posts 49. Good 

 insulation. 50. Expedients for obtaining it. 51. Forms of insulating 

 supports. 52. Dimensions and preparations of the posts. 53. Forms 

 of support used in England. 54. Winding posts. 55. Supports in 

 France. 56. In America. 57. In Germaoy. 58. "Wire insulated 

 by superficial oxydation. 59. Leakage of the electric fluid by the con- 

 duction of the atmosphere. 60. Effects of atmospheric electricity 

 on the wires. 61. Lightning conductors 62. Those of Messrs. 

 "Walker and Breguet. 63. Conducting current into stations. 64. 

 Underground wires. 65. Methods of insulating them. 66. Testing 

 posts. 



LARDNER'S MUSEUM OP SCIENCE. E 129 



No. 33. 



