into the upper edge, and forms a sort of lip whose internal diameter
corresponds exactly to the surface of the plates, b. This rim, J,
is cast in one piece, and carries on its circumference two small,
diametrically opposite iron studs, which are so placed that they may
engage in the groove, p, at the upper edge of the shells, F.

The second of the two pieces is a cast iron bottom, K, which works on a
hinge-joint, and which is perforated with a large number of holes for
giving passage to the oil that has traversed the hair cloth cushion of
which we shall speak further on. These holes must correspond accurately
with the radial conduits presented by plate, E, and through which flows
the oil to a circular channel running around this same piece. In order
to exactly maintain such a relation between the holes and channels, the
piece, E, is provided with a stirrup-iron, d, that passes around one of
the columns, C, of the hydraulic press.

The entire filter thus constructed is attached to one of the columns,
C', of the hydraulic press in such a way that it can revolve around it.
For this purpose, the column is surrounded by an iron sleeve, L, cast in
two pieces, and which in its lower position rests on the shoulder, e, of
the column. The filter is connected with the sleeve by means of screws,
as shown in Fig. 6.

We shall now describe the mechanism for loosening the band, I, and
moving the bottom, K.

The band, I (Figs. 5 to 9), is cleft at a point in its circumference
corresponding to one of the joints of the shell, F, and carries at each
side of the cleft a bearing in which turns freely a steel pin. One
of these latter, i, is cylindrical, and the other, j, has eccentric