HISTORY AND PROGRESS. 



139 



system is carried upon the axis on which the drum F and a 

 fly are fixed. The clockwork is therefore stopped when 

 the armature is at rest, or 

 when no current passes. 

 When, however, the arma- 

 ture is attracted, the 

 friction-spring E is raised 

 from F, and the clock- 

 work starts ; a boot, T, 

 hanging from the beam 

 and resting on the rim of 

 the revolving drum M, is 

 lifted up, and continues to j^ 7^ 



dance upon the rim by the 



friction of the drum in revolving. After the current ceases 

 the armature is released, and the boot, descending on the 

 drum, is carried off by the rotation, not allowing the spring 

 E to stop the clockwork until after the last current has ceased 

 for some seconds. The starting of the clockwork may be 

 effected at pleasure by the operator, by raising the friction- 

 spring E, and it may be stopped by pressing it against the 

 ivory break- wheel. 



86. The Polarised Ink Recorder used as a Submarine Key. 

 Translation. The manner in which the ordinary Morse 

 apparatus is connected up for translation has already been 

 explained. It is performed with the polarised apparatus 

 as follows : 



When the tongue of the relay G 15 Fig. 78, of the receiving 

 apparatus is deflected against the local contact, the local 

 battery is put into circuit, and the printing instrument draws 

 the beam H X from the screw 2 to the screw 3, the former 

 being connected with the counteracting battery K, and 

 the latter with the line battery + K. When the printing 

 beam is connected by s 2 and I with the line L 2 , supposing 

 the printing lever H L to be resting against the contact 2, 

 a negative current enters the line L 2 in the following 

 way : K, earth, opposite station apparatus, L 2 , /, S 2 , H X , 2, K. 

 But when the printing lever H t is attached to the contact 3, 



