IRON MANUFACTURE. | 491 
a marked feature in the landscape. The cost of this method of stripping 
may be approximately estimated as follows: one man can remove 12 
cubic yards of earth per day, at a cost of $1.50, or 123 cents per cubic 
yard. Assuming the depth of earth to be 12 feet, and the ore as 1 foot 
in thickness, each 12 cubic feet of earth removed will expose 1 cubic 
foot of ore, which may be removed at 30 cents per cubic yard. The 
cost per ton of ore will hence be, regarding 12 cubic feet of ore as equal 
to 1 ton of 2,240 pounds: 
Removing 5.33 cubic yards of earth, at 123 cents............c0000seeeeee $0 66 
Removing 0.44 cubic yards of ore, at 30 Cents...................0seeeeeeeee 0 13 
CLG OH ELHTRYOVON Ayer FOETP (WOT, GLO CHA c0000600080000000000660063060800 050000 $0 79 
For a seam of 6 inches the cost would be on the same estimate, 
$1.46, and for an 18-inch seam, $0.57. In stripping for the ore no very 
systematic method has been pursued, for, when the ore is wanted the 
miner, or rather ore digger, has much liberty as to where he shall dig 
the ore, and he opens the seam much as he may choose, being paid so 
much per ton of 2240 pounds, delivered at the furnace, the company 
furnishing the haulage. Benching is unquestionably the cheapest 
method, and for those ores below 1 foot in thickness the only one 
possible, but for seams of one foot or more, regular mining operations 
could be adapted. ‘The limestone ore, as stated, has been thus obtained 
in some instances, and possibly one of the block ores would also warrant 
a similar course. The course best adapted would seem to be to run 
good roomy entries, about 100 feet apart, on the seam, either from the 
hill-side, or, where it is deeper, from shafts, and then to connect them by 
parallel galleries. The entries would thus serve for mining out the ore 
in cars, and the ore could be removed in the cross galleries by the 
“‘long-wall system.” This method enables all of the ore to be worked 
out, and requires but little timbering, for as fast as the ore is stripped 
up the refuse can be thrown behind, and the roof allowed to fall in. 
A rough estimate of such a course of extraction, less the expense of 
maintaining the tram-ways, cars, etc., can be approximated as follows, 
assuming the cost of mining at $0.75 per cubic yard, and the weight of 
ore as 187.5 lbs. per cubic foot (specific gravity, 3): ina bed of ore, 1 
foot thick, each cubic fathom of earth removed yields 36 cubic feet of 
ore, or 3 tons, which will thus cost $2.00 per ton. 
Between the years 1870 and 1873 the value of these different ores 
