228 University Geological Survey of Kansas. 
broken rock, when cleaned out, leaves a cavity large enough 
to introduce a number of sticks of powder, and so reduces 
the tendency of the charge to react along the line of the drill 
hole. 
Advantage is taken of the cracks and crevices existing in 
the rock mass; also any lines of weakness which may be ap- 
parent on examining the rock face. By this method of pro- 
cedure a very irregular system of drilling is necessary; but 
each shot will be more effective than it is possible to obtain 
by a more systematic arrangement of holes, such as is neces- 
sary in machine drilling. Power drills are largely taking 
the place of hand drills, but as they are, as a rule, operated 
by steam instead of air, considerable inconvenience and 
trouble are experienced in their use. 
Tempering of Tools. 
The tempering of drills and picks is quite a problem when 
the mining operations are carried on in bard material such 
as the flint formation of this district. The blacksmith must 
keep himself informed as to the nature of the formation work, 
in order to be able to properly temper the tools. 
A tool tempered to cut flint will break in limestone, as 
limestone is tough; and when tempered to work in lime- 
stone will cut and batter when used in flint, as the tool must 
be made soft in order not to break in the tough rock. All 
limestone or all flint of a certain, fairly constant degree of 
hardness is easily worked, but both occurring together or 
either one varying considerably in hardness makes very bad 
work in drilling. 
No rule is followed in tempering. A so-called tempering 
is done by ‘‘heat’’—that is, noting the degree of heat by the 
‘‘feel.’’? It is a rare occurrence to find a smith who tempers 
by drawing the heat and sets the temper by color. The plea 
is made that not sufficient time is given to temper by color, 
yet a tool will be sent to the shop to be reformed and tem- 
pered twice when, if it were done properly at first—that is, 
tempered by color—the second forming and tempering would 
be unnecessary in many cases. 
The temper for a tool, drill or pick used in cutting or 
