ct
on the same general principle;--that of forcing the clay through a
ring-shaped aperture in an iron plate, forming a continuous pipe, which is
carried off on an endless apron, or on rollers, and cut by wires into the
desired lengths. The plates with the ring-shaped apertures are called
_dies_; the openings are of any desired form, corresponding to the
external shape of the tiles; and the size and shape of the bore, is
determined by the core or plug, which is held in the centers of the
apertures. The construction of the die plates, and the manner of fastening
the plugs, which determine the bore of the tiles, is shown in Fig. 43. The
view taken is of the inside of the plate.

[Illustration: Fig. 43 - PLATE OF DIES.]

Fig. 43 - PLATE OF DIES.

The machine consists usually of a strong iron chest, with a hinged cover,
into which the clay is placed, having a piston moving in it, connected by
a rod or bar, having cog-teeth, with a cog-wheel, which is moved by horse
or hand power, and drives the piston forward with steadiness, forcing the
clay through the openings in the die-plate. The clay issues in continuous
lines of pipe. The machines most in use in this country are connected
directly with the pug-mill, and as the clay is pugged, it at once passes
into the box, and is pressed out as tiles. These machines are usually run
by horse-power.

Mr. Barral, in his voluminous work on drainage,(25) describes, as follows,
a cheap hand machine which can be made by any country wheelwright, and
which has a capacity of 3,000 tiles per day (Fig. 44):

"Imagine a simple, wooden box, divided into two compartments. In the rear
compartment there stands a vertical post, fastened with two iron bolts,
having heads at one end, and nuts and screws at the other. The box is thus
fixed to its support. We simply place this support on the ground and bind
its upper part with a rope to a tree, a stake, or a post. The front
compartment is the reservoir for the clay, presenting at its front an
orifice, in which we fix the desired die with a simple bolt. A wooden
piston, of which the rod is jointed with a lever, which works in a bolt at
the top of the supporting post, gives the necessary pressure. When the
chest is full of clay, we bear down on the end of the lever, and the
moulded tiles run out on a table supplied with rollers. Raising the
piston, it comes out of the box, which is again packed with clay.