ALBERT C. RITCHIE, GOVERNOR. 715

the last cut-through in the entry, excepting that room-necks
may be broken off by workmen driving entries, when approved
by the district mine inspector. Whenever any working places
are driven to destination or to the boundary, or are stopped,
such places shall be connected at the face by cut-throughs.

SEC. 100. Every such mine shall be divided into ventila-

tion districts or splits of not more than 75 men in a dis-
trict, unless in the judgment of the district mine inspector
such limitation in any particular mine is impracticable, when
such inspector may by written safety order permit a larger
number, not exceeding 100 men, to work therein. In a gaseous
mine the district mine inspector may by written safety order
require a further subdivision of ventilation districts to include
a smaller number of men than 75. Every such ventilation dis-
trict shall be supplied with a separate current of fresh air,
and the return air current therefrom shall be conducted direct
or through an overcast or undercast to the main return airway
or outside the mine.

SEC. 101. All temporary stoppings necessary during the
progress of mining shall be strong and tight, and be replaced
by permanent stoppings as quickly as possible unless other-
wise authorized by the district mine inspector. All perma-
nent brattices and all permanent air bridges, overcasts and
undercasts shall be substantial, amply strong, of materials ap-
proved by the district mine inspector and kept tight. All
. doors shall be so hung and adjusted that they will close of
themselves, and on main haulage roads, wherever possible, a
second door shall be hung in the same air current, so that
the opening of one door shall not interrupt the air circulation.
Doors on main haulage roads, not self-closing, shall be served
by an attendant whose constant duty it shall be to open such
doors for persons and cars to pass through and to close it im-
mediately after them. When a door is used in conducting the
main air currents, an extra door shall be provided and kept
standing open, out of reach of accident, but ready for im-
mediate use in case of any damage to the door regularly in
service.

SEC. 102. In mines employing more than ten persons at
any one time, unless the required ventilation is pro-
vided by other approved means, not a furnace, such
ventilating current shall be provided bv fan of sub-
stantial type, ample capacity and, at gaseous mines or