STATISTICS AND INFORMATION. 2793

1922, ch. 307, sec. 102.

103. In mines employing more than ten persons at any one time, un-
less the required ventilation is provided by other approved means, not a
furnace, such ventilating current shall be provided by fan of substantial
type, ample capacity and, at gaseous mines or when required by regula-
tion, reversible at the will of the operator, which shall not be located di-
rectly over the entrance to a shaft, the air passage from which into the
mine shall be strongly built and kept tight, and which shall be provided
with a self-registering pressure gauge, the record whereof, duly dated,
shall be accessibly filed at the' mine office and there preserved for one year
for reference. Such fan shall be kept continuously in operation while
the mine is working, and during such further periods as the Bureau may
prescribe, unless written permission to stop such fan shall be given by the
district mine inspector; and before stopping such fan after such permis-
sion given, notice thereof shall be given every employee of the hours dur-
ing which stoppage is intended to continue, and work shall not be re-
sumed until such fan has run two hours continuously. Provided, that
should it at any time become emergently necessary to stop the fan because
of mechanical failure or other unavoidable cause, it shall first be the duty
of the mine foreman to provide for the safety of persons within such
mine, either by removing them or by furnishing temporary ventilation;
but no ventilating furnace shall be employed in such temporary emer-
gency in a gaseous mine. No principal fan shall be placed inside any
mine; nor shall an auxiliary fan be placed in any mine except under regu-
lation of the Bureau.

1922, ch. 307, sec. 103.

104. The operator shall, by the mine foreman or other competent per-
son, at least once every week in non-gaseous mines, and daily or as required
by the district mine inspector, in gaseous mines, when the men are work-
ing, measure the air current with a correct anemometer at or near the main
intake and outlet, and also in the last cut-through in the last room and in
the entry beyond the last room turned in each entry; and the air traveling
through pillars being drawn; and enter in a book kept for that purpose a
true report of all such air measurements, designating the place, the area
of each cut-through and entry separately, the velocity of the air in each
cut-through and entry and the number of men employed in each separate
split or district at the time the measurement was taken, with the date;
signed by the person taking the same; which record shall be kept in the
office at the mine, open to examination by the Bureau or by any person
employed in such mine. Once each month a report of the air pressure
average as shown by the pressure gauge upon the ventilating fan, the
daily air pressure during the principal shift, the air pressure by districts
and number of men and animals working in each district, the average air
circulation at the last cut-through and entry extension in such districts
and the lowest and highest air circulation observed at such points at each
examination, and such other information as the Bureau may require, shall