30 cwt. to 4 tons attached
to the lower bar. In some cases four guides are used--two to each of the
long sides of the cage; but a more general arrangement is to have
three--two on one side, and the third in an intermediate position on the
opposite side. Many colliery managers, however, prefer to have only two
opposite guides, as being safer. The cage is connected by tubular clips,
made in two pieces and bolted together, which slide over the ropes. In
addition to this it is necessary to have an extra system of fixed guides
at the surface and at the bottom, where it is necessary to keep the cage
steady during the operations of loading and landing, there being a much
greater amount of oscillation during the passage of the cage than with
fixed guides. For the same reason it is necessary to give a considerable
clearance between the two lines of guides, which are kept from 15 to 18
in. apart, to prevent the possibility of the two cages striking each
other in passing. With proper precautions, however, wire guides are
perfectly safe for use at the highest travelling speed.

Ropes and chains.

The cage is connected with the drawing-rope by short lengths of chain
from the corners, known as tackling chains, gathered into a central ring
to which the rope is attached. Round steel wire-ropes, about 2 in. in
diameter, are now commonly used; but in very deep pits they are
sometimes tapered in section to reduce the dead weight lifted. Flat
ropes of steel or iron wire were and are still used to a great extent,
but round ones are now generally preferred. In Belgium and the north of
France flat ropes of aloe fibre (Manila hemp or plantain fibre) are in
high repute, being considered preferable by many colliery managers to
wire, in spite of their great weight. A rope of this class for a pit
1200 metres deep, tapered from 15.6 in. to 9 in. in breadth and from 2
in. to 1-1/8 in. in thickness, weighed 14.3 tons, and another at Anzin,
intended to lift a gross load of 15 tons from 750 metres, is 22-1/2 in.
broad and 3 in. thick at the drum end, and weighs 18 tons. Tapered round
ropes, although mechanically preferable, are not advantageous in
practice, as the wear being greater at the cage end than on the drum it
is necessary to cut off portions of the former at intervals. Ultimately
also the ropes should be reversed in position, and this can only be done
with a rope of uniform section.

Winding engines.

The engines used for winding o