Page:The American Cyclopædia (1879) Volume V.djvu/75

COLLIERY 71 insecure. In the great mining districts of the world, both in coal and metalliferous mines, the ladder and the hoisting apparatus are the alternatives. To ascend and descend a pit of 1,000 to 1,500 ft. on ladders is nearly a day's work, while descent or ascent on the cages is dangerous. The number of accidents caused by the falling of cages or cars in the anthracite mines during 1871 was 13; and this has always been a fruitful source of mining accidents, part- ly from the crowding of men anxious to be first at work or first at home, on the cages or into the mining cars. The mining laws of most of the great mining districts prohibit the use of unsafe cages, and the crowding of men on either the car or the cage; but these laws are seldom enforced. The hoisting apparatus, elevators, or lifts used in hotels and manufactories are too slow for mining purposes; and though numer- ous safety cages have been invented, few if any are perfectly secure. Many " safety- catch" arrangements, however, are in use, which if kept in order would generally prevent serious accidents. The two most practical forms of clutches seem to be the " claw " and the "eccentric." The former are thrust out into the timbers or guides, and the latter hugs the guides on opposite sides when the rope breaks. One defect, however, of all such ar- rangements, very difficult to overcome, is that they sometimes act during the rapid descent of the cage, which in some cases is equal to the speed of a railroad train, and little short of the motion at the start in falling from a broken rope. Consequently all such devices are de- fective in pits, and the best cages are unsafe means of conveyance for the workmen. Yet on these, or still more rude and dangerous con- veyances, or on ladders, ninety-nine out of every hundred miners depend for descent to and ascent from their work. In a few cases, du- ring late years, " travelling rods " have been used with considerable success, though but rudely contrived and fitted up. They consist of two perpendicular oscillating rods, generally of wood, placed side by side and parallel to each other in the travelling apartment of the pit. Some of these are simply provided with steps, without guards, while in others the rods have platforms securely guarded against danger. In other cases, however, a single rod is used, on which platforms are fixed at intervals, with corresponding stationary platforms in the rock; but the latter plan is much inferior to the for- mer, in which the rods are so balanced that the power required jto operate them is but little, while the single rod must be lifted with its weight of men, ascending or descending. In descending the miner steps on one of the mov- ing platforms which comes to the top of the pit, and as this only remains a few seconds, during the slow motion of turning the upper centre of the operating wheel, he must be ready to step on without delay, though a fail- ure to do so would not be dangerous. The motion may be five to ten strokes per minute without difficulty. Immediately on reversing the rod descends 8 to 12 ft., meeting a corre- sponding platform on the ascending parallel rod; on this the miner steps, and the platform he left ascends, and the one he is on descends. Thus he steps from platform to platform and descends from 100 to 200 ft. per minute. In ascending the same rule is observed, except that the miner steps upon the ascending plat- form instead of the descending one; but whe- ther ascending or descending, he is alternately now on one, and now on the other; and though 20 or more miners may be going up or going down at once, the balance is always nearly equal. The best mode of constructing these rods is to place them close together, with the platforms on opposite sides; and instead of two, four rods are preferred. In stepping from one platform to the other, the miners pass between the rods. In order to prevent accidents from carelessness or otherwise, the platforms should fit the compartments neatly, so that the men could not even by thoughtlessness endanger life or limb. In the construction of such means of vertical convey- ance, in pits of great depth, iron or steel bands, links, or ropes could be judiciously made use of, connected on top by square links over a toothed wheel, making alternate reverse revolutions. The methods of sinking pits have been consid- erably improved within a few years, by the use of new me- chanical contrivances, or inven- tions in boring, blasting, and contending with water, quick- sands, clays, or hard materials. FIG 16 Travel- ^ n W astm ^ the U8e ^ dualline iing Bods, is preferred by miners to other a, basket plat- new explosive compounds, on forms; 6, c, par- accoun t O f its superior safety SSSJ^USt and effectiveness; while elec- tricity is now generally used by experienced engineers both in sinking and tunnelling. It is not used, nor is it de- sirable, in ordinary coal or iron mining for the discharge of single blasts; but where the simultaneous discharge of numerous blasts is required, nothing but electricity is available. In the sinking of two deep vertical shafts by the Philadelphia and Reading coal and iron company 1| m. N. of Pottsville, a novel meth- od was adopted, which promises to produce a revolution in that branch of mine engineering. The mammoth coal bed in that locality lies at a great depth below the surface, estimated to be 1,560 ft., and as the mining law of the state requires at least two openings separated by not less than 150 ft. of solid strata, two shafts were necessary. The plan adopted wa.<*