1874.] Copper Mines of Lake Superior. 175 
leaves out, however, the cost of the motor power. In the 
Quincy Mine, the same drills are being thrown aside as 
uneconomical,—a discrepancy in result which may be 
accounted for by the fact that in the Calumet there is a well- 
defined salvage, whereas in the Quincy the drifts are run 
through solid rock, and grooves must be scooped out 
beneath the face of this advancing drift,—an operation not 
easily performed with a cumbrous drill. 
The ore is broken in two ore-houses, each of which is 
provided with a pile driver to shatter the large masses—a 
Blake’s crusher with 18 by 24 inch opening, and six smaller 
Blakes, with 8 by 15 inch openings, but no attempt is made 
at selecting by hand, but all the ore raised passes to the mill. 
From the crushers the ore falls into huge hoppers, whence 
it is discharged as called for into the railway cars. All the 
appliances, in fact, are ona scale such as we are in the habit 
of associating with iron mining. A five-mile railroad unites 
the concentrating works on Torch Lake with the mine, and 
over it two hundred ‘car-loads of 4-ton capacity each are 
carried daily. 
The mills present no feature of special interest. In one 
are three of Ball’s stamps, and in the other four. Six of 
these powerful machines are running regularly, and crush 
up the whole yield of the mines. To each stamp there are 
assigned 20 jigs. 
The stamps are steam-hammers. The slide valve is 
worked by eccentric gearing, and the piston-rod is inserted 
into the head of the shaft, which is g inches in diameter. 
The stamp-head is 22 by 14 inches, and weighs 6cwts. Its 
upper surface is provided with a bevelled ridge, which slides 
into a slot in the bottom of the shaft, and is then keyed 
home. When working on the amygdaloidal trap, Ball’s 
stamp heads, made with white iron and a small percentage 
of Franklinite and tough pig, lastamonth. At the Calumet 
Mills they are worn out in six days, but the renewal involves 
a Stopping of the stamp of only 50 minutes. Each stamp 
works in a separate stamp-box, which is five-sided, and 
discharges from three sides through steel plates, perforated 
with 3-16th inch holes. Each stampcan crush daily 120 tons 
of this exceedingly hard rock, and is said to consume 25 horse- 
power; 3000 gallons of water a minute are pumped to the 
two mills. The great advantages of using the stamp are 
that so much work can be done with so little machinery and 
‘In so contracted a space, and that so little time is occupied 
in repairs. The Calumet Mills never stop. The Quincy 
mill is idle for about one month out of twelve. 
