CORRIMAL-BALGOWNIE COLLIERIES. 



213 



swept clean, then when the machine is put in action, if cor- 

 rect, the point of the steelyard will vibrate gently in the 

 guide. If it is not quite right it may be regulated by ad- 

 justing a small weight situated near the fulcrum. In the 



Fig. 136. 



more modern machines this is concealed within the pillar to 

 protect it from interference, and is manipulated by the key (K) 

 through the hole (H). If, when the small weight is moved 



