Transactions . Fig. ]. —Chemical Mine Fire-encixe. Swpjjorting Exca-vations by Concrete.—At the Burnside col-liery of the Phila-delphia and ReadingCoal and Iron Com-pany, Pennsylvania,concrete inches forthe support of mainroads in place oftimber are in , some 18 in-ches square, were. Fig. Arching at BurnsideColliery, Pennsylvania. used to replace timber sets, 14 to 16 inches square. The designof the arches is shown in fig. 2, and the cost varied from £4 £o 10s. per arch. These arches have successfully carried theweight, which previously caused continual breakage of
Transactions . Fig. ]. —Chemical Mine Fire-encixe. Swpjjorting Exca-vations by Concrete.—At the Burnside col-liery of the Phila-delphia and ReadingCoal and Iron Com-pany, Pennsylvania,concrete inches forthe support of mainroads in place oftimber are in , some 18 in-ches square, were. Fig. Arching at BurnsideColliery, Pennsylvania. used to replace timber sets, 14 to 16 inches square. The designof the arches is shown in fig. 2, and the cost varied from £4 £o 10s. per arch. These arches have successfully carried theweight, which previously caused continual breakage of the MINING AND ENGINEERING IN AMERICA AND CANADA. 115 timbers. There are, no doubt, cases where an extended use ofconcrete would be desirable for the support of excavations inEnglish mines. Power-stations, etc.—Montreal is being supplied with electricpower from the Shawenegan Falls, which are situated on the river, halfway between Montreal and Quebec. The totalheight of the falls from the upper to the lower lake is about 140feet, and the total available power is estimated at about 100,000horsepower. In designing the power-station, the chief question was whetherthe turbines should have a vertical or a horizontal shaft. AtNiagara, as will be seen later, the turbines are p
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Keywords: ., bookcentury1800, booksubjectmechan, booksubjectmineralindustries
