evidence of such examination, the fire boss shall mark with chalk
upon the face of the coal, or in some other conspicuous place, his
initials and date of the month upon which the examination is made.
If there is any standing gas discovered, he must leave a danger
signal across every entrance to such place.


[=Examination of other than working places.=] Each mine generating
fire-damp so as to be detected by a safety lamp, shall be kept free
from standing gas. All traveling ways, entrances to old workings,
and places not in the actual course of working, shall be carefully
examined with a safety lamp by the fire boss not more than three
hours before the appointed time for persons employed therein to
enter. Parts of the mine not in the actual course of working and
available, shall be examined not less than once each three days, and
shall be so fenced as to prevent persons from inadvertently entering
therein. (Sec. 955, 959; Penalty, Sec. 976.)


Sec. 926. [=Breakthroughs and brattices.=] From a point where the
seam is reached in the opening of a mine, to a point not exceeding a
distance of four hundred feet therefrom, breakthroughs shall be made
between main entries, where there are no rooms worked, not more than
one hundred feet apart, provided such entries are not advanced
beyond the point where the breakthrough will be made until the
breakthrough is complete. Breakthroughs between entries, except as
hereinbefore provided, shall be made not exceeding sixty feet apart.
Where there is a solid block on one side of a room, breakthroughs
shall be made between such room and the adjacent room not to exceed
sixty feet apart; where there is a breast or group of rooms, a