GLOSSARY. 



GLOSSARY. 



After damp. The mixture of gases left after a colliery explosion, 

 consisting of carbon dioxide, carbon monoxide, nitrogen, and water. 



Air drift. A drift connecting a ventilation shaft with the fan. 



Air lock. An intermediate passage closed at either end by a 

 door, placed between airways, along which currents of different pres- 

 sures are flowing. Persons desirous of passing from one airway to 

 the other can do so without interfering with the system of ventilation 

 or personal inconvenience. 



Air receiver. A strong vessel, into which air from a compressor is 

 delivered, which serves as a reservoir to equalise the pressure before 

 being consumed. 



Air shaft. A shaft used specially for ventilation purposes; 

 generally the upcast. 



Alligator. A self-tipping tank, used for raising rock or coal while 

 sinking stopes or jigs. 



Anemometer. An instrument used for determining the velocity of 

 a current of air. 



Arris-cleat. A strip of wood, having a triangular cross-section 

 used for keeping brattices in position. 



Backing-deal. Planks placed against the inside of shafts, the rock 

 of which requires support; the planks are kept in place by wedging 

 them against curbs. Generally used for temporary purposes prior to 

 bricking up. 



Sand. A thin layer of rock in a seam of coal. 



Band-or strap-rope. An endless rope that transmits power from 

 the surface into the clutch-room underground, where the various dis- 

 trict ropes are thrown into gear. 



Bank. The surface round about the top of a shaft. 



Bank of ovens. A row of ovens for converting coal into coke. 



Banker off. The man who attends to taking skips off the cage. 



Banksman. See Banker off. 



Bar. See Cap-piece. 



Barrier pillar. A long block of unworked coal left between two 

 collieries, or between workings under water, and those under land, so 

 as to guard against accidents. 



Basin. A coal basin is a large basin-shaped depression, in which 

 coal seams occur. 



Battery of ovens See Bank of ovens. 



Beehive oven. A coke oven, having the appearance of a large old- 

 fashioned straw beehive. 



BeU-slieave -A sheave in the shape of a truncated cone 3 used in 

 connection with the main and tail system of rope haulage at curves, 

 so as to keep the rope close to the ground. 



Silly. A name used in the Clermont district of Queensland for a 

 bed of quartzite that caps the coal measures. 



Billy-fair-play. A trough with a swinging bottom attached to a 

 spring balance for Aveighing slack when it passes through the screens. 



Black-damp. Chiefly carbon dioxide gas, due to the oxidation of 



