Ice wall, a barrier of frozen ground formed by the ‘freezing method’ of shaft sinking.Idle back, -see ‘Check rail’.
Idle rope, the return rope on an endless rope haulage. The rope that does not bear a load. (Scot.).
Idlers, -see ‘Rollers’.
Ill air, a stagnant atmosphere underground due to lack of ventilation. Noxious gas from an underground fire or chokedamp. (Scot.).
Immediate roof, the strata immediately above a coal seam. -see Nether roof.
Impact ripper, a ripping machine using a boom mounted impact unit to deliver repeated high energy blows at the rip by means of a reciprocating pick.
In-bye or Inbye. To travel into a mine is to go ‘in-bye’, i.e. in a direction away from the shaft. The opposite is ‘out-bye’.Also ‘inwan’ (Scots.).
Incline, another word for a dip or dipping roadway, as in ‘self-acting incline’.
Incrop, A former outcrop concealed by or buried beneath younger unconformable strata. Also called a ‘subcrop’.
Indicator, a mechanical device in the winding-enginehouse which shows the position of the cage in the shaft.
Ingate, -see ‘Inset’.
In-gaun-ee, i.e. ‘ingoing eye’, the mouth of a drift mine; or a coal seam that outcrops at the surface (Scot.). Also called a ‘Day Level’, ‘Drift’ or ‘Day-eye’.
Inrush, a sudden, unexpected large make of water or other flowing material, such as sand or peat, into the mine, very often of serious proportions, causing casualties and disruption to coal production.
In-saem mining, a system of mining in which the development headings are driven within the coal seam.
Inset or Mouthing, the entrance to underground roadways at the bottom or part way down the shaft where the cages are loaded and there is access for men and materials. Also called a ‘Porch’ or ‘Inset’.
Intake, any roadway underground through which the fresh air from the downcast is conducted to the working faces.
Interaction, the effects on underground workings from old workings either above or below due to the re-distribution of stress in the ground.
In the bell, a device to stop overwinding of the cage - a detaching hook combined with the bell – releasing the rope in the case of an overwind.
Intrinsically safe, a machine which is safe in itself without having to be placed inside a flameproof enclosure.
Inwan, another word for ‘inbye’ (Scots.). – see also Outwan.
Iron balls, ironstone nodules.
Iron Man, mechanical coal cutter. (S. Staffs). Also called a ‘pig’; or the name given to one of the earliest coal cutters by Firth of Leeds, designed in 1870.
Ironstone, an iron rich sedimentary rock, usually of some economic importance now or in the past. In the coal measures, the two main types are clayband and blackband ironstones.
Iron timbers, a term used by older miners for steel supports when they were introduced into mining.
Issues, collieries fortnightly permitted output of coal decided by cartel. (N. East).
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