extend along the middle row, the tops of the boxes on which wires rest being removed. The exploders, b, b, b, are inserted in giant-powder cartridges and placed on top of the paper covering the powder.
The wires A A and D D are then connected with the wires Y Y' and Z Z', which extend to the battery.
Tamping.—Great
care should be used to prevent the " blowing-out" of the tamping, which
results not only in considerable loss of effect, but often causes great
destruction to property and even to life. It is advisable, when firing
blasts by fuse, to tamp nearly the entire main drift. The gravel
extracted from the drift is used for this purpose, and should be fairly
dry and as free as possible from large stones, which cause great
damage in case
