The disagreements of bibliographers concerning this book have not been restricted to controversies about its date and printer. Some have said that there were no types in any of the editions, and that the letters, like the pictures, were cut on solid blocks of wood. This error is almost pardonable. The superficial observer of our own time will say that the characters of this book are not types, but badly engraved letters. They seem to lack the most distinguishing feature of types. The letters are not at all alike, as may be seen in the accompanying fac-simile. The variations in the shapes of the letters are so frequent that a modern printer would at once decide that the dissimilar letters could not have been cast in the same matrix. This is a curious defect, but it can be shown that the letters are types, and founded types. “The existence of a positive fact,” says Chatto, “can never be affected by any arguments which are grounded on the difficulty of accounting for it.” It is plain, however, that the types of the book were carelessly made by an inexpert type-maker, and perhaps by a clumsy method now out of use. Instead of making all the types of one character from one punch or original, the printer of this book made them from two, four, or six punches or originals. At this point it is not necessary to consider why so many punches were made. It is enough to say that there is real uniformity in the midst of all this diversity—that each letter is a duplicate, more or less faithful according to the wear it has received, of its own original. Careful tracings on transparent paper have been repeatedly made of a selected letter [p274] for the purpose of testing its agreement or disagreement with letters of the same kind on other pages, and the comparison establishes the fact that the letters are founded types.[136] The errors of the _Speculum_ are those of types. They show the inversion of letters in positions which preclude the possibility that they could have been formed upon engraved blocks. The occasional occurrence of a _c_ for an _e_, of an _n_ for a _u_, of an _ſ_ for an _f_, and the “turning upside down” of other letters, are examples of errors which can be made only by compositors. The unequal perspicuity of the letters in the _Speculum_ is that of unequally worn types. Of two adjoining letters, one will be distinct, black, and deeply indented in the paper; the other will be of dull color, and of indistinct outlines. The distinct letter is a new and high type, which has received the full force of impression; the indistinct letter is an old and worn type which has been touched but feebly by impression. If all the letters had been engraved on one plate, they would have been of equal height, and should have been equally legible, or nearly so, under impression.