MINING. 131 
Instead of copper wire, iron rods of 5 or 6 times the sec- 
tional area of the copper wire, will answer equally as well 
or better, for conveying power underground. 
For conveyance of power from the surface to endless rope 
systems that are not very distant from daylight, the rope 
itself, driven by a steam engine at the surface, and moving 
at the rate of 11 miles per hour, is the cheapest and most 
economical conveyance of power to underground haulage. 
There is nothing more certain than that in the future, wire 
rope haulage power and the electric power, will be used 
extensively in underground mining operations. It may be 
safer to be wary and move cautiously in their adoption, in- 
creasing their use gradually, still it is only a matter of 
time as to their general adoption. 
In the gangway of our Cahaba Field mines, the overhead: 
electric wire would be too dangerous if not insulated. In. 
fact all electric wires of high voltage placed in mines should 
either be insulated, or placed in narrow channels so that 
there would be no possible chance of the minor coming in 
contact with them. 
The storage battery with electric motor (thus doing with- 
out wires), is the best and safest mathod of underground 
electric haulage in gangways that are level, or nearly so. 
In conveying power to pumps or drills, there is no neces- 
sity for using any but insulated wires. 
