blemishes, which could have been produced only by means of transferred drawing.[139] With this fact before us, the supposition of the priority of an engraved edition of the book is untenable. Dutch authors say that these xylographic blocks corroborate a Hollandish legend, in which it is stated that the materials of the printer of the _Speculum_ were stolen. They suppose that the first typographer was obliged to engrave [p278] these twenty blocks to complete his imperfect edition. This hypothesis does not accord with other facts: the appearance of three successive editions of the book, each with a text of types, proves that the practice of typography was continued. [Illustration: Fac-simile of part of a Page of the Speculum Salutis.] The provision of black ink for the types and brown ink for the cuts seems unnecessary, but Van der Linde’s explanation of this peculiarity is plausible. He says that the oily black ink used on the types may have been rejected for the cuts because its greasy surface interfered with the brush of the colorist. It does not appear that the inquiry has ever been made, whether the brown ink of block-books was always brown. It is probable that this brown ink was once black. The variability of the color, so frequently remarked in all block-books, is the certain indication of a faded black writing ink. It was the fluidity of this writing ink that prevented its use on the types of the _Speculum_; the fluid collected in globules on the metal, spreading under impression, and blotting the paper. Oily ink was required for a surface of metal. The unequal indentation of the letters indicates that the types were not of a uniform height. Nor is it probable that the engravings at the head of every page were always truly flat and of precisely the same height as the types. They were pieces of flat boards, which must have warped with every change from heat to cold, or from dampness to dryness.[140] In these irregularities we find the probable reason for the employment of two distinct methods of impression. Two impressions were needed as much as two kinds of ink. [p279] The types required strong, and the wood-cuts weak impression. If the impression had been graduated to suit the wood-cuts, the print of the types would not have been visible; if enough impression had been given to face the types, the wood-cuts, if in the same form, would have been crushed.