GLOSSARY. 409 



gases developed from highly heated coal dust, and gases sucked out of 

 the faces of coal by the partial vacuum resulting from the primary 

 explosion, or liberated by falls of roof. 



Second working. The extraction of pillars left by the first working. 



Self-actiny incline. Sec Gravity plane. 



Set. (1) A set of skips, is a rake or row of skips connected to- 

 gether to form a train. (2) The timbers which compose any framing. 

 Avhether for a roadway or a shaft. (3) To place a pro]) in position. 



Set rider. The man who accompanies a set of skips hauled by the 

 main and tail rope system, so that he can attend to any points on tho 

 track, unfasten the rope, and signal to the engine-driver as required. 



Shaft. A. vertical or highly inclined pit sunk in connection witb 

 mining operations. 



Shaft pillars. The solid block of ore left about a shaft in order 

 to protect it from being destroyed. 



Shandy -gaff. Shovel-filled coal. 



Shearing. See Nicking. 



Shift. The number of hours constituting a man's ordinary daily 

 work. 



Shiftmen. Men engaged on wages at various jobs. 



Shipper. An instrument used for placing an endless rope on its 

 rollers in cases where it gets off them. 



Shoes. (1) The bottom wedge-shaped piece attached to tubbing 

 when sinking through quicksand. (2) Steel pieces fastened to the 

 ends or sides of cages, which slide on guides when the cage is in motion. 



Shooter or shot firer. The man who fires a charged hole after satis- 

 fying himself that the place is free from fire-damp. 



Shooting fast. Shooting in the solid, i.e.,, making powder do all 

 the work without holing or undercutting. 



Short wall machine. A coal cutter for use in bords, which, when 

 once the cutting part has made the sumping cut., is drawn acro.ss the 

 face automatically by ropes, undercutting as it proceeds. 



Shot. The explosion of a charged hole. 



Shovel filled. Run-of-mine coal as broken at the face. 



Skip. A coal miner's truck. 



Skirfini/.A road driven next a fall of stone or next to an old 

 fallen place. 



Slack. Fine coal, which will pass between bars -Jin. apart. 



Slack l>o.i'. A bill in which slack is stored. 



Slant. An inclined roadway. 



Slip. A. small fault. 



.S7/'^ hook. A hook, generally on a hinge, which can be readily dis- 

 connected by withdrawing a cotter bolt that holds it in position. 



Slope. An inclined roadway, generally driven from the surface. 



Xmall coal. See Slack. 



Speak. Props are said to "speak" when they give signs of weight 

 by cracking. 



Spear-wedges. Long wooden wedges, used for centering iron tub- 

 bing, and which help to pack up the space between the tubbing and 

 the rock. 



Special places. Development and difficult places, where coal can- 

 not be won so easily as in ordinary working places. 



Splint or splent coal. An inferior laminated dull-look iny; coal con- 

 taining much ash. 



Split. (1) To divide an air current into two or more; also the 

 divided current itself. (2) When a coal seam is divided by a parting 

 into branches, it is said to split. 



Spontaneous combustion. Combustion started by natural means. 



Sprat/. (1) A piece of wood or iron placed between the spokes of 

 ski]) wheels, which jambs against the bottom of the skip ;:nd pre- 



