28 CHARLES HIGGINS 



lying at an angle and often broken by faults. It is necessary 

 to follow the dip or angle of inclination of the bed in mining 

 for such deposits. This is determined by tracing down the 

 outcropping of the vein, if there be one, by cutting a passage- 

 way or incline that follows the slope of descent, or by sinking 

 a vertical shaft and running horizontal passageways— drifting 

 as it is called— to the lode or vein. Deposits in high hills are 

 reached by driving a tunnel into the hillside. 



After determining the dip of the vein approximately 

 a working shaft is sunk, at the angle taken by the vein, or 

 vertically, and from this shaft, at different levels, horizontal 

 drifts are cut, drilled or blasted through the deposit. Through 

 these horizontal passageways the ore is drawn to the shaft 

 through which it is hoisted in cars to the surface of the ground. 



There are many methods of extracting the ore but they 

 vary with the formation of the veins and seams of ore, and 

 with the nature of the deposit. One plan is extraction of 

 the ore by slicing it off from the top in successive layers, but 

 the usual plan followed is to drill and blast from a working 

 level to the next level below. 



In coal mines the passages entering the seams at the 

 working levels from the shafts are called gangways. They 

 may run in any direction towards the seam, around it or 

 through it and from these gangways other passageways are 

 driven off breasts in which the miners work cutting into the 

 seam. In coal mines where the deposit is hard anthracite, 

 the gangways are often ten and twelve feet wide and from 

 twelve to twenty five feet high, while the breasts are from 

 twenty to thirty feet wide and separated by intervening walls 

 or pillars from fifteen to seventeen feet thick. The breasts 

 and gangways are supported by heavy timbers, surmounted 

 by cap pieces and cross pieces and set at intervals varying 

 with the nature of the deposit. 



In ore mines the drift or passages are run along the length 

 of the vein and often when the vein is narrow a single drift 

 is sufficient to enable workers to exhaust it. When the vein 

 is wide, parallel drifts, intersected by cross cuts, are made 

 ranging from four and a half to five by seven feet, within 

 the buttresses used to support the roof and walls of the gang- 



