_Details of Structure_.--The filter, which is shown in detail in Figs. 5 to 7, is formed of two semicylindrical cast iron shells, F, that are firmly united, and held by a strong iron band which is cleft at one point in its circumference, and to which there is adapted a mechanism permitting of loosening it slightly so as to facilitate the escape of the oil-cake. Within these shells, F, there are grooves, a, which have the arrangement shown by the partial section in Fig. 11, and through which flows the oil expressed by pressure. To prevent the escape of the material through these grooves or channels, the interior of the shells is lined throughout with plates or strips of brass that fit very closely together, and present a simple slit with chamfered edges opposite the grooves. At the two joints of the shells four of these plates are riveted two by two; all the others are movable, and rest, like the pieces of an arch, against the fixed plates that form abutments. Each half lining is thus held by means of a central plate, b' (Fig. 10), with oblique edges, and which, being driven home by the top of the filter, binds the whole tightly together. All these plates, which are slightly notched at their upper part, rest on a small flange at the lower part of the shells. [Illustration: FILTERING PRESS FOR OLEAGINOUS SEEDS.--AUTOMATIC INJECTION PUMP] As regards their manufacture, these plates are cut out of sheets of perfectly laminated brass, and are afterward set into a matrix to center them properly. After the shells have been bored out, all the plates are mounted therein so as to obtain a perfectly cylindrical and uniform surface. The plates are then numbered and taken out; and, finally, a slit with chamfered edges is cut longitudinally through them, save at three points--two at the extremities and one at the middle. The plates thereafter rest against each other only at these three points, and leave at the chamfered places capillary openings just sufficient to give passage to the oil, but not to the pressed paste, however fine it be. As will be seen in Fig. 5, the points of contact are not in the same horizontal plane, but are arranged spirally, so that the flow will not be stopped at this place as it would be were these solid parts all at the same height. The filter, F, is completed by two pieces that play an important part. The first of these is a cast iron rim, J, which is set 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.