It is not at all probable that the press of the unknown printer had these handy appliances. All the printing presses made before the nineteenth century had wooden frames, with beds of slate or stone, and platens or pressing surfaces of wood. Impression was given by the direct action of a screw, the force applied being regulated only by the discretion of the pressman. Knight, in his essay on Caxton, says the press of that printer was a modification of the cheese-press, provided with an attachment that permitted the form of types to be moved in and out of the press. German authors say that the first printing press was a modification of the wine-press. Bernard says it was, probably, an improved form of coining or stamping press. But these are only conjectures. We can find no engraving nor any verbal description of the form of the printing press in use during the fifteenth century. The general neglect by all artists and writers of this important auxiliary to printing is an indication that no importance was attached either to the mechanism of the press or to the principle of impression. It seems to have been generally understood that, whatever merit there might have been in the invention of printing, no noteworthy inventive skill had been shown in the construction of the press. It was not only a rude but an old contrivance. We have many evidences that the press of the unknown printer was of the rudest construction. Some pages have the marks of strong pressure in one corner and of weak impression in another—manifestly the result of the printer’s inability to regulate or control the force he exerted. The margins of the _Speculum_ are of unequal width; the type-work is rarely ever parallel with the engraving at the head or at a proper [p305] distance from it. On some pages, the types overlap or bite on the wood-cuts; on other pages they are too near or too far from them. One of the reasons why the _Speculum_ was printed on one side only was the deficiency in this press of any contrivance for determining the proper position of the sheet before the impression was taken. The pressman could not print one page truly and squarely on the back of another page. Koning says that the printer did not have the least idea of the means to be used for accomplishing this result.[162] This defect of the press can be seen in the pages of the small books without illustrations: they were printed on both sides, but the modern printer would condemn the work as seriously out of register.