MINING. 115 
of the mass may be cut vertically to a considerable depth without any fear 
of its caving in. Care should be taken that no heavy weight is placed on 
the edges of the pit. On account of the situation of peat beds, they can 
rarely be thoroughly drained without great cost. Where the water can be 
managed by buckets, small trenches can be dug, and the peat easily 
obtained by means of the usual spade (jig. 27) or the spade with sides or 
wings (jigs. 28a and 28 6). Where the peat-bed is covered with water, and 
the draining is too expensive, the peat is obtained with nets. For obtain- 
ing soft peat a net is used, similar to that with which sand is obtained from 
the bottoms of rivers. If the peat is firm enough, a rim of hoop-iron is 
used, on the circumference of which a net is fastened. The rims of the 
nets used in Holland are from 12 to 22 inches in diameter. The peat 
obtained by the net can be dried in drying-boxes or moulds. 
4. Drirts or LEVELS. 
The excavations intended to reach veins or localities of ore in order to 
unite them with the surface of the earth, and which have a small sectional 
area in proportion to their length, are called drifts and levels, or shafts, 
according as they approach a horizontal or perpendicular direction. 
The adit or adet-level is a horizontal gallery, terminating in the open air, 
and which generally serves for draining the mine. Levels are horizontal 
excavations driven on the lode. Cross-cuts are levels driven at right angles 
with others to intersect the lode. 
The mode of working the levels, and the tools used for the work, vary 
according to the condition of the rock to be operated upon. In hard rock 
the levels are driven without the support of carpentry or masonry. In soft 
and crumbling rocks carpentry or masonry must immediately follow the 
mining operations, and frequently precede them. In hard rock the levels 
are mined by blasting or by means of hammers and picks, or strong steeled 
wedges or gads ( pl. 28, jigs. 31 a and 316). A section of the drift or level 
has usually the form of atrapezium. The upper side is semicircular. The 
height of the level may be 5 to 6 feet, and the width at the bottom from 3 
to 4 feet; but generally the height is 6 feet, and the width at the bottom 
4 to 5 feet. The adit level serves at the same time for conducting off and 
obtaining water. When the water covers the bottom several inches deep, 
the adit may be divided into two parts by a horizontal partition, which is in 
fact the roof of the conduit for the water. On this roof is constructed the for- 
warding floor, and beneath it, on the floor of the adit, the water flows from 
the mine. The roof of the conduit is 14 or 16 inches above the bottom of 
the drift, and the gallery above this roof is 5 to 6 feet high. The roof of 
the conduit consists of boards, which are nailed on beams or sleepers. 
Drifts or galleries with a very large cross-section, called tunnels, are driven 
forward by steps, so that the part of the tunnel which is being wrought has 
the appearance of a flight of stairs with several broad steps, each one of 
which can be occupied by a workman, The obtaining of a cubic foot of 
695 
