I would recommend, contrary to the general practice, that in wooden presses the winter should lie solid in the mortises of the cheeks, and have no spring; and that all the spring should be in the head, which would not affect the perpendicular descent of the platen. This method of constructing a press would be found advantageous in all cases; but more particularly in one-pull presses, in which the platens are large: —
For it must be obvious, where an uniform impression is meant to be obtained from types, by means of the perpendicular descent of a body with a plane surface, that this surface and the surface of the types should be parallel to each other, and that every variation from these parallels must affect the equality of the pressure.
It being a necessary consequence, that the surface of the types should be horizontal; it will be equally clear, that every departure from this horizontal line will destroy the parallelism of the two surfaces, and prevent an equal pressure on all their parts.
One part of the carriage of a press lies on the winter, the other end resting on, and confined to, the forestay, which is fixed to the floor, and cannot give way; the coffin, in which is the press stone, lies on the carriage; and on the press stone the types are placed.
Now, when great pressure is applied to the types, to produce an impression, it causes the winter to give way, which immediately disturbs the horizontal plane of the types, and destroys the parallel between them and the face of the platen, and causes an unequal pressure, besides straining the cords of the platen, the platen itself, and all the parts connected with it, to the injury of the workmanship, and of the whole machine; all which would be avoided by the winter being laid solid in the mortises of the cheeks, and the carriage and ribs justified by a level. It would also be attended with another advantage, — not being so liable to slur in running in; the inner tympan not being so close to the platen.
This principle is equally applicable to iron presses, as well as to wooden ones; and will tend to preserve them a longer time in good condition.