ed for the wheels.
The former are used chiefly when it is required to turn wagons or trucks
of light burden, or, in the case of earthworks, for trucks of moderate
weight. These plates are quite portable; their weight for the 16 in.
gauge does not exceed 200 lb. For engineering works a turntable plate
with variable width of track has been designed, admitting of different
tracks being used over the same turntable.

When turntables are required for permanent lines, and to sustain heavy
burdens, turntables with a cast iron box are required, constructed on
the principle of the turntables of ordinary railways. The heaviest
wagons may be placed on these box turntables, without any portion
suffering damage or disturbing the level of the ground. In the case of
coal mines, paper mills, cow houses with permanent lines, etc., fixed
plates are employed. Such plates need only be applied where the line is
always wet, or in workshops where the use of turntables is not of
frequent occurrence. This fixed plate is most useful in farmers'
stables, as it does not present any projection which might hurt the feet
of the cattle, and is easy to clean.

The only accident that can happen to the track is the breaking of a
fish-plate. It happens often that the fish-plates get twisted, owing to
rough handling on the part of the workmen, and break in the act of being
straightened. In order to facilitate as much as possible the repairs in
such cases, the fish-plates are not riveted by machinery, but by hand;
and it is only necessary to cut the rivets with which the fish-plate is
fastened, and remove it if broken: A drill passed through the two holes
of the rail removes all burrs that may be in the way of the new rivet.
No vises are required for this operation; the track to be repaired is
held by two workmen at a height of about 28 in. above the ground, care
being taken to let the end under repair rest on a portable anvil, which
is supplied with the necessary appliances. The two fish-plates are put
in their place at the same time, the second rivet being held in place
with one finger, while the first is being riveted with a hammer; if it
is not kept in its place in this manner it may be impossible to put it
in afterward, as the blows of the hammer often cause the fish-plate to
shift, and the holes in the rail are pierced with great precision to
prevent there being too much clearance. No other accident need be feared
with this line, and the breakage des