It has also been argued by some writers, among whom is William Blades, that the letter was not printed in colour, but that the design was merely impressed in blank upon the paper or vellum, and afterwards filled in with colour by the illuminator. This is shown, it is said, by some portions of lines here and there in the ornamentation remaining uncoloured, a result surely due to imperfect inking rather than to a careless illuminator. It is hardly probable that the rubricator would begin a line and leave the end uncoloured while it was plainly traced for him; but, on the other hand, it is just such a fault as would, and often did, occur in printing an elaborate and involved ornament. No doubt in some cases the capitals, like the letters of the text, were touched up by the rubricator; and this is, as a rule, most noticeable when the ornament or letter is in blue. The blue ink used had a green tinge, and in some cases looked almost grey, and was therefore very often touched up with a brighter colour. Mr. Weale is of opinion that these letters were not set up and printed with the rest of the book, but were ‘printed, subsequently to the typography, not by a pull of the press, but by the blow of a mallet on the superimposed block.’ It was probably about 1458, between the times of printing the two editions of the _Psalter_, that Schœffer printed the book called in his catalogue of 1469-70, _Canon misse cum prefacionibus et imparatoriis suis_. This was the Canon of the Mass, printed by itself for inserting in copies of the Missal. This particular part, being the most used, was often worn out before the rest of the book; and we know from early catalogues[8] that it was the custom of printers to print this special part on vellum. While the printing of a complete Missal would have been a doubtful speculation, the printing of this one part, unvarying in the different uses, required no great outlay, and was almost certain to be profitable. Two copies only are known, and these are of different editions. One is in the Bodleian, and was bound up with an imperfect copy of the _Mainz Missal_ of 1493. The other is in the Imperial Library at St. Petersburg, in a copy of the _Breslau Missal_ of 1483. [8] In a catalogue issued by Ratdolt about 1491 we read: ... ‘videlicet unum missarum (?) in papiro bene corporatum et illigatum cum canone pergameneo non ultra tres florenos minus quarta: sed cum canone papireo duos florenos cum dimidio fore comparandum.’ The Bodleian copy consists of twelve leaves, printed on vellum in the large type of the _Psalter_, and ornamented with the same beautiful initials. The capital T of the _Te igitur_, commencing the Canon, is as large as the well-known B of the _Psalter_, and even more beautiful in execution. Besides the ordinary coloured capitals which occur also in the _Psalter_, there is a monogram composed of the letters V.D., standing for _Vere dignum_.