1048 LAWS OF MARYLAND. [CH. 437

Timber removed by cutting-machine or loading-machine
operators or knocked out by blasting shall be replaced
promptly, unless they are not needed for adequate roof
support or protection.

(c) Testing of roof, ribs, and face. It shall be the
duty of the mine foreman, assistant mine foreman and
mine inspectors to ascertain if workmen understand roof,
rib, and face testing. Uninformed workmen and new em-
ployees shall be instructed properly in correct methods of
testing.

Face workers and other employees exposed to hazards
from falls of rock and coal shall, unless this testing is
specifically and satisfactorily performed by others examine
and test the roof, ribs, and face before starting work or
before starting a machine and frequently thereafter. When
dangerous conditions are found, they shall be corrected
immediately by taking down loose material or by proper
and adequate timbering before work is continued or any
other work is done.

During work on any shift, the mine foreman in charge
of the shift or his designated assistants shall examine, or
cause to be examined by a competent person, roof, ribs,
and face of working places and passageways where men
travel, for dangerous conditions. Where found, such dan-
gerous conditions shall be corrected promptly by remov-
ing loose roof or rib, by adequate timbering, or duplication
of defective timbering where necessary. Such timbering
shall conform to the clearance provisions hereinafter
provided.

When there is danger of coal rolling on a person during
or after undercutting or center cutting, it shall be spragged
by placing blocks in the cut or by blocking with leaning
posts.

(d) Removal of timber. In worked-out places where
timbers are being removed, persons engaged in drawing
timber shall not be permitted to work alone.

83. 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 them as soon as persons and cars are in the
clear, however, where it is not feasible or practical to
install self-closing doors, the Bureau of Mines is author-
ized, after a thorough study of the operating conditions
of each particular mine, to prescribe rules relating to the
duties of the said attendant. It being the legislative intent
that self-closing doors should be installed whenever feasi-
ble and practical in the discretion of the Bureau of Mines