THE LOCALISATION OF BREAKS AND FAULTS. 



375 



For reducing the sensibility of the instrument for speaking 

 purposes, mechanical damping is adopted in the shape of a 

 brush of fine camel's hair, DB, touching the top portion of the 

 suspension. The position of the brush is adjustable forward or 

 backward in the frame, so as to produce more or less friction 

 against the suspension wire with proportionate mechanical 

 damping. This adjustment for speaking can be instantly- 

 made, and when the brush is withdrawn the instrument is at 

 once restored to its former con- 



dition of sensitiveness without 

 requiring any re-adjustment. 

 Signals can be exchanged with 

 shore on the shortest or longest 

 cables and any adjustments 



Uetal Strip 

 ~ Suspension 



-Mirror 



Fixed Soft- 

 Iron Core 



Aluminium 

 " Frame 



LW 

 Lead Wire 

 for balancing 



■Fixed end 

 of Lead Wire 



^^^Metal Strip 

 Suspension 



Fig. 223. 

 Sullivan Galvanometer Suspension. 



necessary made on board without asking the shore to make 

 any change in his conditions. 



For the purpose of balancing for rolling and pitching, small 

 lead wires are fixed at the front and back faces of the coil at 

 LW, which can be bent outwards from the coil or inwards to- 

 wards the face to produce more or less effective weight on either 

 surface, and so balance the suspension. 



The instrument is electrically damped by the closed metallic 

 circuit formed by the aluminium frame on which the coil is 

 wound (Fig. 223) and also by the coil itself when in connec- 

 tion with a circuit or shunt. When used with plain shunts 



