Recent Changes in Gold Mining 
125 
1907] 
for an additional set. When the old timbers have been re- 
placed the entire flooring- of sets is easily put in as the ore 
is removed; a temporary plank covering may be placed across 
the old timbers to protect the men from falling rocks. Tem- 
porary plank floors are placed upon the sets for the men to 
stand upon and, as the system becomes higher, chutes and 
mill holes are put in to conduct the ore to the car on the 
track below. Any waste rock mined is merely dumped in 
and around the lower sets. 
There has been little or no trouble indtroducing the square 
set method of timbering and at the Union Copper Mine the 
work is done under the immediate supervision of Mr. Hed- 
rick, a skilfull North Carolina shift boss who has had no 
previous experience with square sets. Some of the miners, 
especially negroes, when first stoping by means of square set 
timbering are a little nervous because they are so close to the 
roof that they can see how loose the rocks are; but they 
soon realize that they can pick down the loose rock or prop 
it up and, therefore, are safer than when they are so far 
away that they cannot tell at what moment the rock may fall 
upon them. Also when working at the bottom of a high, 
1 underhand stope, a blow from even a small rock would be 
dangerous. 
CYANIDE PLANTS. 
The introduction of the cj^anide process for treating certain 
sulphuret ores is a third change in mining practice in the 
State that has added considerable to the production of gold. 
One of the most successful cyanide plants was the one erected 
to work the tailings of the Howie mine, near Waxhaw, Union 
County. This mine is in a zone of hard, siliceous slates, carry- 
ing chimney-like bodies of pretty high grade ore. The gold 
is all free but so finely disseminated that the high grade ore 
which.is a laminated or schistose quartz has merely a golden 
sheen. A great deal of this escaped amalgamation although 
enough was saved to pay well. These old tailings, which are 
rumored to have been worth 5 or 6 dollars a ton, soften 
