Figure 77.-Miner receives day's supply of permissible explosive from surfacemagazine keeper in morning and carries it in wooden "powder box." He uses an electric cap lamp. Federal Bureau of Mines says permissible explosive is safest explosive to use in coal mines. Careful shot firer uses no other kind.

Figure 78.-Miner receives checks from keeper of surface magazine to be given to shot firer when detonators are used in the miner's working place.

Figure 79.-Miner loads and fires his own hole, using coal dust for stemming and tamping the hole with a steel bar. He has not removed the "bug dust." This is dangerous practice. A spark from the steel tamper may set off the shot. The coal-dust stemming may cause a blown-out shot. The blown-out shot may blow the bug dust into the air and start a mine explosion.

lamp.

Figure 81.-Shot firer tests for gas before preparing shot. He has the detonator box over one shoulder and the firing wire over his other shoulder.

Figure 82.-After testing for gas, the shot firer measures the bore hole to see that it does not extend beyond the undercut and determines that it points properly. He puts the detonator box and the wire carefully on the floor.

Figure 83.-After measuring the bore hole, the shot firer measures the

Figure 85.-Miner gets "powder box" from its hole in the rib 100 feet or more from the face. The hole is whitewashed to warn miners that explosive is kept there.

Figure 86.-Miner brings "powder box" to shot firer. He is careful not to bring it near the detonator box.