412 GLOSSARY. 



for large ventilation fans of the Guibal type, which by cutting off the 

 discharge of air gradually, reduces the vibration. 



ir</7(//i{/ curb. A curb on which a Avail is built for a _ shaft lining. 



Washing coal. Dressing coal in order to get rid of dirt associated 

 Avith it, so as to reduce the ash forming material. 



Wash out. The erosion of part of a seam by aqueous action. 



Water baler. A man who bales water out of dip workings in 

 places where it is not convenient to put in a pump. 



\Vater gauge. An U-shaped glass tube, containing water, by means 

 e-f which the pressure of an air current can be measured. 



Water-ring. A trough let into the wall of a shaft in which water 

 collects, and is led doAvn pipes to a pumping station. 



Water table. A horizontal surface drain placed across a track. 



Wedging curb. A ring of wood or cast iron securely wedged in 

 position at the bottom of a section of tubbing, so as to form a water- 

 tight joint. 



\Ve-ighinan. A man who Aveighs the coal as it comes out of the 

 mine. 



\Vell hole. The sump, or portion of a shaft below the place where 

 skips are caged at the bottom of the pit ; used for water to collect in. 



Wclsh-bord. A bord in which the Avaste is stored in the middle, 

 and a roadway is kept open on either side. 



Wet place. A place is considered Avet if men have to work con- 

 stantly in Sin. of water or more, or Avhen water is constantly dripping 

 on them from the roof. 



Wheeler. Lads Avho drive horses that draw skips to and from 

 working places, and the nearest collecting station. 



White-damp. Carbon mon-oxide, a very poisonous gas. 



White stone. An indurated clay band in the Greta seam, thickly 

 strewn with plant impressions. 



Whole-working. Working in the Avhole, or first Avorking of a seam, 

 by which it is divided up into pillars. 



Wind blast. A quantity of air driven out with considerable force 

 by a fall of roof. 



Winning bord. A bord from which coal is being Avon. 



Winning-off. A leading heading or drive in advance to win room 

 for bords. Any leading drift is termed a "Winning." 



Winning pillars. Extracting coal pillars. 



Working bord. See Winning bord. 



W 7 orbing, first. See Whole-working. 



Working in the broken. See Second working. 



Yardage. A price paid per yard for cutting coal, in addition to 

 the tonnage rate, in order to compensate for the breaking of coal more 

 frequently from the sides in narrow places. The amount of j-ardage 

 paid varies with the width of the working place. 



