In driving gangways or chambers toward abandoned workings that have been allowed to fill with water much care is necessary, especially if the new mine is on a lower level, which is usually the case. The act of 1885 provides that “whenever a place is likely to contain a dangerous accumulation of water, the working approaching such place shall not exceed twelve feet in width, and there shall constantly be kept, at a distance of not less than twenty feet in advance, at least one bore hole near the centre of the working, and sufficient flank bore holes on each side.” It often happened, before accurate surveys of mines were required to be made and filed, that operators would drive chambers or gangways toward these reservoirs of water in ignorance of their whereabouts. The firing of a blast, the blow of a pick, perhaps, would so weaken the barrier pillar that it would give way and the water breaking through would sweep into the lower workings with irresistible force, carrying death to the workmen in its path and destruction to the mine. Some very distressing accidents have occurred in this way. It is customary now for operators, when approaching with their workings a boundary line of property, to leave a barrier pillar at least one hundred feet thick between that line and the outer rib or face of their workings; and this whether the area on the other side of the line is or is not worked out. Under the present system of accurate surveying and mapping, accidents resulting from flooding by mine water should be rare, since the location of boundary lines may be calculated almost to the inch, as well as the location of all workings in their relation to each other. But accidents due to a flooding by surface water are not always to be obviated. Sometimes when a stream crosses the line of outcrop the water will break through into the mine and flood the lower levels in an incredibly short space of time; and this too when good judgment and prudence have been used in leaving sufficient coal for protection. The continuity and character of the strata lying between the earth’s surface and the coal face cannot always be determined. It is not often that accidents from flooding occur while mining is going on under large bodies of water. The precautionary measures taken in presence of a known danger are sufficient to reduce that danger to a minimum.