114 TECHNOLOGY. 
quarry are under the charge of two superintendents, one of whom directs 
the labors of the quarry, and the other those above-ground. After the 
soil and clay produced by the decomposition of the slate, which is often 
quite thick (jigs. 5, 6, and 7), have been removed, the rock is worked by 
steps or banks about 10 feet high each, as is shown in figs. 6 and 7, so that 
an oblong square excavation is formed. Two walls in the quarry are made 
vertical. On the firmest of one of the upper steps, a wooden platform is 
erected. This platform carries a pulley, upon which runs the hoisting rope 
( jigs.6 and 7). The platforms are connected by bridges, with sheds, a B ¢, 
where the steam-engines are set up. In commencing the quarrying, a notch 
is made with a pickaxe, and widened into a trench of about 3 feet broad 
( jig. 6), and the slate is taken out on both sides, so that the quarry has 
always steps upon which the workmen may take their places. To cut in 
each step, the workmen dig in the fissures of the rock with their pickaxes a 
series of notches, in which wedges are placed (pl. 25, figs. 31 ¢ and d), 25 
or 80 of them for every 28 or 35 feet. The workmen all stand in a line, 
each man to a wedge, and smite with heavy hammers on the wedges, keep- 
ing time in their blows. As the slate splits open and the wedges sink, 
thicker ones are put in their place, until the rock breaks at the bottom and 
tumbles down. When the rock cannot fall by its own weight, an instru- 
ment, represented in pl. 25, jigs. 34 a and b, is aid in the cleavage of the 
slate. To this a rope is fastened, and pulled by ten or fifteen men. /%gs. 
32 a and 33 show a hand crowbar which is used. The steps cut on each 
side of the shaft are indicated by the horizontal lines on fig. 6. For some 
time past blasting has been used to advantage, several holes being charged 
and fired off at once. 
When a block is quarried off, it is divided by means of the irons ( pl. 25, 
jigs. 81 a and 6); the drill-wedge and pick (jig. 30 a 6 and jig. 32 d e), the 
pickaxe and hammer are also used. Lach block is divided into pieces of 
convenient size. The pieces are then loaded into boxes (figs. 27, 28, and 
29), and carried up to the top of the quarry. The slate is carried from the 
hoisting-shed to the platforms around the quarry, where it is prepared. 
This is done in the open air. A working gang consists of three persons, two 
splitters and one apprentice. The blocks are divided into smaller pieces, 
having the general form and dimensions of the different kinds of slates. 
The blocks of slate are divided by placing a flat chisel (jigs. 32 6 and e, and 
35) in one of the clearly-marked divisions of the slate, and striking it with 
a wooden mallet. The slates are then laid flat on a wooden block, and 
fully smoothed off with a kind of knife. 
Another kind of work at the surface is the digging of peat. Beds of peat 
occur in the flat regions of rivers in the north of France, Holland, and the 
plains of lower Germany, also on high plains without trees. 
The thickness of a bed of peat may be discovered by the peat-borer (pl. 
23, jigs. 32 and 34). This is a simple half-opened scoop auger, which is two 
or three inches in diameter, and is fixed to a pole 15 or 20 feet long, on 
which is marked a scale for measurement. Peat is usually soft enough 
to be easily dug by means of a cutting instrument, and from the firmness 
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