THE MINING AND QUARRY INDUSTRY I909 7I 



while a quality of green slate known as the unfading green is 

 also quarried to a large extent. 



The slate is taken out from large open pits or quarries, the 

 face afforded by a side hill being often utilized. The blocks are 

 loosened by blasting and by the use of bars, etc. Hoisting is 

 efifected by means of a traveler carrying a small hoisting cable 

 and running on a larger wire cable strung across the pit. This 

 cable is anchored on one side of the pit and passes over a tall 

 mast on the other, giving an inclined cableway on which the 

 traveler may run. The whole is operated by a small drum hoist 

 which allows the traveler to run out to any position desired over 

 the pit. It is then automatically locked to the cable and the smaller 

 hoisting cable descends from it into the pit to receive its load. The 

 block of slate is hooked to the cable, hoisted to the traveler and by 

 it is carried directly to the trimming sheds or is loaded on cars which 

 are pushed to the sheds. The waste rock, which must be hoisted as 

 well, is dumped in huge conical ipiles around the mast. 



For the manufacture of roofing slate, which is the main use 

 of the slate, the blocks are carried into small sheds, often 

 perched on the dump piles. These sheds are equipped with a 

 trimmer, a few mallets and chisels and some shelving. Two 

 men work in each shed. The block, usually from 4 to 6 inches 

 thick, is turned on edge and carefully split with chisel and mallet 

 into sheets from % to j4 inch thickness. The sheets thus 

 formed are then squared up into rectangular roofing slates. The 

 trimmer used for this purpose consists of two blades resembling 

 lawn mower knives, a heavy fly wheel for giving sufficient 

 momentum, a stationary straight edge beneath the knives, a 

 feeding plate and a treadle to set the knives in motion. The 

 slate is fed under the revolving knives and is thus sheared off 

 an inch or so at a time until trimmed to the proper size. The 

 larger slates bring the better prices and some skill is needed in 

 the splitting and trimming. The men employed are paid either 

 by the hour or by the square. 



The slate used for billiard table tops, electrical switchboards, 

 stair treads, and other purposes where slabs are required, is 

 known as mill stock. For these purposes, certain beds only are 

 suitable, and quarrying is conducted in the same manner as for 

 roofing slate. The blocks are then dressed in mills where they 

 are first sawed by circular toothed saws and then planed smooth 

 on a planer and polished or rubbed on a rubbing table. The 



