3240 ARTICLE 89

the owner or operator doing so, shall order such mine closed until the
unsafe conditions are corrected.

"Non-Gaseous Mine" is a mine which has not been rated as gaseous;
or a mine which, having been rated as gaseous, has been re-rated as non-
gaseous as prescribed in the definition of a gaseous mine, elsewhere in this
section.

"Operator" means any firm, corporation, association or individual op-
erating any coal mine or part thereof, whether as an owner, lessee or
otherwise, and also includes the representative of such operator.

"Panel" means a unit area in a system of mining by which the mine is
divided into large rectangles or panels isolated or surrounded by solid
pillars of coal into which pairs of entries are driven for the development
of rooms and the extraction of pillars.

Permissible: Unless the context requires a different sense, "permis-
sible" means the admission of a device, plan, formula, method, machine
or course of action by the United States Bureau of Mines to a list, after
actual test thereof.

Potential and Voltage: These words shall be taken as synonymous, to
mean electric pressure as determined by the voltmeter.

"Shaft" means an opening, the axis of which is approximately vertical,
extending downwards from the surface; and shall include an underground
shaft driven between two levels.

"Slope" includes an inclined opening in a dipping coal and/or fire clay
bed and an inclined tunnel to a coal and/or fire clay bed.

"Superintendent" means the person who shall, on behalf of the opera-
tor, have immediate supervision of one or more mines.

"Tunnel" means a level or inclined passageway driven mainly through
barren strata. It may or may not come to the surface.

"Ventilating Current" means a current of air circulating throughout
the mine excavations, of such purity that it shall contain not less than 19
per cent, of oxygen nor more than (1 1/4) one and one-fourth per cent,
carbon dioxide. The district mine inspector shall, whenever he has reason
to suspect an excessive proportion of carbon dioxide, or insufficient oxygen
in the atmosphere of any mine, take such tests as the Bureau may pre-
scribe, and upon disclosure of a ventilating current below or approaching
minimum standard, require the operator by written safety order to im-
prove the ventilation immediately.

"Working Place" means a room, breast, entry, cross-cut or pillar where
coal and/or fire clay is being mined or extracted and where one or more
miners per working shift of the mine are regularly employed until the
place is finished or stopped.
As to mining companies, see art. 23, sec. 181, et seq.

TITLE I—ADMINISTRATION.

CHAPTER I—Supervision.
An. Code, 1924, sec. 18. 1922, ch. 307, sec. 17.

17. There is hereby created under the Commissioner of Labor and
Statistics, a department to be known as the "Bureau of Mines," herein-
after referred to as the Bureau.