. Bulletin (Pennsylvania Department of Forestry), no. 8-9. Forests and forestry. 86 fall that represents to a large degree a complete waste and the fact that they are suitable for this line of manufacture should certainly be a means of utiliz- ing a large quantity of this discarded material. Table 55a.âWood for Mine Rollers, year ending June, 1912. Kind of Wood. Quantity. a â »j a .a â¦* 85 4> 6« Pm u Qi bfiX s« o CI d o H Grown In Pennsjl- vania. a xi Grown Out of Penn- sylvania. a Blaolc gum. .. Sugar inai»le, White oal{, .. ISircli, Boeoli, Yellow poplar, Cork elm Total, 1, 27
. Bulletin (Pennsylvania Department of Forestry), no. 8-9. Forests and forestry. 86 fall that represents to a large degree a complete waste and the fact that they are suitable for this line of manufacture should certainly be a means of utiliz- ing a large quantity of this discarded material. Table 55a.âWood for Mine Rollers, year ending June, 1912. Kind of Wood. Quantity. a â »j a .a â¦* 85 4> 6« Pm u Qi bfiX s« o CI d o H Grown In Pennsjl- vania. a xi Grown Out of Penn- sylvania. a Blaolc gum. .. Sugar inai»le, White oal{, .. ISircli, Boeoli, Yellow poplar, Cork elm Total, 1, 277,200 212,080 183,200 123,200 12,000 8,800 2,440,440 $24 38 26 99 30 57 30 70 30 84 .49 18 75 .36 26 14 125 99 $39,588 7,482 6,483 5,624 8,799 225 230 $63,431 219,216 277,200 212,080 183,200 123,200 12,000 8,800 1,035,696 1,404,744 1,404,744 SPRAGS. This is a second division of this industry which deserves special attention, not that it represents a commodity that is important in the amount of wood consumed nor economically prominent in the operation of large factories and the use of skilled labor, but because it serves to illustrate the tendency in Pennsylvania towards waste utilization. A sprag is a cylindrical wooden commodity pointed at each end, about 21 inches long, ranging in thickness from 2:^ to 3^ Inches and is used in coal mining operations for checking and regulating the speed of a mine car as it runs in and out of the laterals leading to the shafts. The speed of the car is checked by locking one of its wheels. This occurs when the sprag, having been cast between the spokes of the rotating wheel, strikes against the car still. Mine cars are not equipped with brakes like freight cars and upon the sprag often depends the safety of the car and more often a train when run- ning downgrade. Sprags must therefore necessarily be very strong and many companies are particular in the specifications of their orders for manufactur- i
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