INSULATING SUPPORTS. 



55. In France the posts are from twenty to thirty feet high, 

 placed at distances varying from sixty to seventy yards asunder, 

 and sunk to a depth of from three to seven feet in the ground. 

 They are impregnated with sulphate of copper to preserve them 

 from rotting by damp. 



The conducting wire rests in an iron hook, which is fastened 

 by sulphur into the highest part of the cavity of an inverted 

 bell, formed of porcelain, from which two ears project, which are- 

 screwed to the post. 



A section of this apparatus is given in fig. 13, and a side view 

 in fig. 14, the figures being one-fifth of the actual magnitude. 



The winding posts are placed at distances of a kilometre (six- 

 tenths of a mile). The apparatus used for tightening the wire 

 consists of two drums or rollers, 

 each carrying on its axis a ratchet 

 wheel with a catch. These drums 

 are mounted on iron forks formed 

 at the ends of an iron bar, which 

 is passed through an opening 

 in a porcelain support, and se- 

 cured in its position by pins, the 

 porcelain support being attached 

 to the post by screws passing through ears projecting from it. 



A front view of this winding apparatus is given fig. 15 ; a 



Fig. 15. 



14 * 



Fig. 16. 



side view of the porcelain support showing the opening through 

 which the iron bar is passed, and the screws by which it is. 

 attached to the post, is given in fig. 16. 

 These figures are one-fifth of the real 

 magnitude of the apparatus. 



The conducting wires used in France 

 are similar to those used on the English 

 lines. 



56. The insulating supports of the 

 wires used on the American lines are 

 very various in form. 



The supports upon the principal 

 Morse lines consist of a glass knob, 



133 



