318 REPORT ON NATIONAL MUSEUM, 1886. 



(6) QUARRYING AND SPLITTING SLATE. 



In quarrying slate the methods vary greatly according to the dis- 

 position of the beds, and no attempt will be made here at a detailed 

 description. Ordinary blasting powder is employed in loosening the 

 blocks, and great skill and sagacity Is shown by experienced quarry- 

 men in so manipulating the blast as to produce the desired effects of 

 freeing the rock from the quarry bed without shattering the stone. 

 After a block is removed from the quarry it is subject to special treat- 

 ment according to the purpose to which the stone is to be put. If for 

 roofing-slate, the block according to Mr. Sperr* is taken from the quarry 

 to the splitters 7 shanty, where it is taken in charge by a splitter and 

 his two assistants. The first assistant takes the block and reduces it 

 to pieces about 2 inches in thickness, and of a length and breadth a 

 little greater than those of the slates to be made. This is done by a 

 process called " sculping," which is as follows : A notch is cut in one 

 end of the block with the sculping chisel, and the edge of this notch is 

 trimmed out with a gouge to a smooth groove extending across the end 

 of the block and perpendicular to the upper and lower surfaces; the 

 sculping chisel is then set into this groove and driven with a mallet 

 until a cleft starts, which by careful manipulation is guided directly 

 across the block. The upper surface of the block is kept wet with 

 water so that the crack may be more readily seen. If the slate is per 

 fectly uniform in shape and texture, and the blows upon the sculping 

 chisel are directed straight with the grain, the crack follows the grain 

 in a straight line across the block. Almost invariably, however, the 

 crack deviates to the right or left, when it must be brought back by di- 

 recting the blow on the sculp in the direction in which it is desired to 

 turn the break, or by striking with a heavy mallet on that side of the 

 block toward which it is desired the crack shall turn. Some slates can 

 be sculped across the grain, but nearly all must be broken in this di- 

 rection. From the first assistant or u sculper" the block goes to the 

 splitter who by means of a mallet and broad thin chisel splits it through 

 the middle, continuing to thus divide each piece into halves until the 

 desired thinness is obtained. It is necessary to keep the edges of the 

 blocks moist from the time they are removed from the quarry until they 

 are split. From the splitter the thin but irregularly shaped pieces pass 

 to the second assistant who trims them into definite sizes and rectangu- 

 lar shapes. This is done either by hand or by machine. To trim by 

 hand a straight edged strip of iron or steel is fastened horizontally upon 

 one of the upper edges of a rectangular block of wood some 2 to 4 feet 

 in length. The trimmer then lays the sheet of slate upon the block al- 

 lowing the edge to be trimmed to project over this strip, and then by 

 means of a long heavy knife with a bent handle cuts off the overlying 

 edge, thus reducing it to the required size and shape. Two kinds of 

 * Report Tenth Census, Vol. x, p. 39. 



