ALBERT C. RITCHIE, GOVERNOR. 687

Duty as applied to a machine or device, means the particu-
lar service in which such machine or device is being employed
or intended to be employed.

Electric Circuit means all conductors, including ground re-
turns, furnishing energy to or receiving energy from electric
apparatus.

Electric System means all apparatus and circuits receiv-
ing electric energy or that may receive electric energy from
a common source. Where the source of power is under con-
trol of the mine, such source of power will be considered as a
part of the electric system. If power is obtained from a cen--
tral station not under control of such mine, the phrase shall
refer only to that part of the system which is under con-
trol of such mine.

Entry means a passage way in a coal bed which is approxi-
mately level and is used for haulage, traveling way,' or venti-
lation. In a dipping bed, entries on the strike are known as
"levels" or "gangways" and to the dip are known as "slopes."

Excavations and Workings: The term "excavations and work-
ings" includes all the excavated portions of a mine, whether
abandoned or being worked; also all underground workings
and shafts, tunnels, and other ways and openings, and all
such shafts, slopes, tunnels, and other openings in the course
of being sunk or driven, together with roads, appliances, ma-
chinery and material connected with the same below the sur-
face.

Faces: The term "face" shall mean the advancing breast
of a mine working-place, either of an entry or room.

Gas is used in the sense ordinarily employed by miners, to
mean "fire damp," and inflammable gas, chiefly composed of
methane, sometimes accompanied by ethane (C₂H₆) in case
of leakage of natural gas, and explosive when mixed with air
in certain proportions.

Gaseous Mine is one in which methane occurs in the mine
atmosphere in such quantities as may become dangerous. If
the percentage of methane in the main return exceeds one-
half of one per cent., or in any split, or single return ex-
ceeds three-tenths of one per cent., the mine shall be con-
sidered a gaseous mine. Samples of the mine air shall be
taken in duplicate for testing purposes when the ventilating
current in such mine and mine conditions have been normal
for at least twelve hours; and when a sample is found to
exceed the limits, duplicate samples shall be taken and tested.