breakthrough to the nearest corner of the entrance to the room, and thereafter breakthroughs shall be made not to exceed eighty feet apart on each side of the room.  No working place, except those provided for within a distance of four hundred feet of the principal openings of a mine, shall be driven more than eighty feet in advance of a breakthrough or air-way.  The required air current shall be conducted to the breakthrough nearest the face of such entry or room.  All breakthroughs between entries, and when necessary between rooms, except the one nearest the working face, shall be closed and made air-tight by brattice, trap doors or other means, so that the current of air in circulation may sweep to the interior of the mine.  Brattices between permanent inlet and outlet airways shall be constructed in a substantial manner of brick, masonry, concrete, or non-perishable material.  In mines generating fire-damp, so as to be detected by a safety lamp, the air current shall be conducted by brattice, or other means, near enough to the working face to expel the fire-damp, and prevent the accumulation of the same. (Penalty, Sec. 976.)

Sec. 927. [=Safe appliances for hoisting persons.=] The owner, lessee or agent of a mine shall provide and maintain safe appliances, approved by the district inspector of mines, for the ingress and egress of persons in each shaft, designated by such owner, lessee or agent as a means of ingress and egress for persons employed therein.  When there is but one shaft available for ingress and egress from any unavoidable cause, the appliances therein shall be kept available to persons therein employed at all times.  When such appliances in any shaft are rendered unavailable from any cause, the same shall be restored without delay.

[=Emergency appliances.=] When the only means of egress is by vertical shaft, in which cages or elevators are used as a means of hoisting persons therein employed, and the power for operating same is derived from but one source, the owner, lessee or agent shall provide and keep on hand for use in the event of an accident to the hoisting apparatus or the power by which same is operated, a suitable windlass, capable of hoisting the persons from the mine.

[=Competent engineers.=] The owner, lessee or agent of a mine worked by a shaft or slope, shall put in charge of an engine used for lowering into or hoisting out of such mine persons employed therein, only experienced, competent and sober engineers. (Sec. 916, 928; Penalty, Sec. 976.)

Sec. 928. [=Metal speaking tube and safety appliances.=] The owner, lessee or agent of a mine operated by shaft, shall provide and maintain a metal tube suitable for conversation between persons, connecting the engine room with the top and bottom of such shaft; an approved safety catch, a sufficient cover, and rings or other adequate handholds for ten persons, on all cages used for lowering and hoisting persons:  Such cages to be protected on each side by a boiler plate not