GLOSSARY. 411 



mounted on a trolley or other movable bearing,, so that the slack of the- 

 rope can be readily taken up by the pull of weights. 



Thimble. The iron ring placed a few feet below the pit-head pulley 

 which supports the safety detaching hook in case of an overwind. 



Third-hand assistant. A boy, who helps the machinist and his= 

 assistant with a coal-cutting machine. 



Throw. The vertical displacement of a fault. 



Throw-off switch. A switch by means of which an obstruction is- 

 thrown across the rails of a track, causing the derailment of trucks. 



Thrust. The cutting up of the roof by the pressure of remaining, 

 pillars of coal in a partly-worked coal mine. 



Tipper. The man who runs skips into a tippler. 



Tipple. The tracks, trestles, screens, etc., at the entrance to a 

 colliery where coal is screened and loaded. 



Tippler. An apparatus for tipping a skip up, so as to empty it of 

 its contents. 



Token. A metal or leather ticket stamped with a distinctive num- 

 ber fastened to a skip so as to indicate to the weighmaii what party 

 mined the coal. 



Tommy dodd. A series of small pulleys., with vertical axles placed 

 between the rails at a curve, so as to keep an endless rope in place. 



Tonnage rate. When miners are paid by the ton. 



Top coal. The upper portion of a thick seam, often left to be 

 extracted at the same time that the pillars are drawn. 



Top-gas. Fire-damp. 



Top man. Any man employed about the surface. 



Trailer cable. A branch cable for conveying electricity to a coal- 

 cutter, one end of which is clipped to the main cable. It is capabli 

 of being paid out as the machine advances. 



Trapper. A lad whose business it is to open and close ventilation 

 doors in roadways along which hauling is done. 



Travelling belt. A conveyor belt. 



Travelling road. An underground gangway, along which men 

 travel to and from their work. 



Travelling weight. See Underweight. 



Trepan. A composite tool for boring holes of large diameter in 

 rock. 



Triple entry. A system of opening a mine by driving three main 

 parallel entries. 



Tub. See Skip. 



Tubbing. The lining of a circular shaft, generally of cast iron, 

 but sometimes of brick or timber, used to keep back water. 



Turn off. The point where a branch line junctions with another 

 line. 



Turn out. A siding or passing place for skips on a haulage road. 



Twin seam. Two seams of coal so close together that they can bo- 

 worked in conjunction or one following closely on the other. 



Undcrcast. An air passage carried under another air course which 

 is the more important roadway. 



Underweight. The travelling weight which rolls forward on the 

 face of the coal in loiigwall work, and breaks down the strip that has 

 been undercut. 



TJnscreened coal. "Rnn-of-mine coal. 



Up-cast. A shaft up which air ascends. 



Up-set. See Copt or Broken skip. 



Vend. A combination of colliery owners in the Newcastle district, 

 having for their object the regulation of the coal trade. 



Viewer. An old term for a general manager or mining engineer 

 of one or more collieries. 



Walker shutter. A shutter having a V-shaped cut in it, provided 



