One most important fact was established by this process, and must be noted. In the Perez Codex at least, _nothing is to be taken for granted_, nothing charged to a careless scribe, and no variants regarded as being identical in value--with a very few exceptions, to which I shall advert later. Wherever there remains enough of any glyph to show its characteristic strokes, it can be regarded as safely indicated; whenever the strokes are not just those characteristic of any glyph, it cannot be inferred. Down to the very end of the various revisions I found myself able to add glyphs which at first seemed hopeless, and yet when once seen became clear and plain. Relying on the presence of the photographs to check the work, I have thus added a very considerable number to the glyphs at first apparent. In some cases, as in 6-b-11 and 17, and especially in 8-b-7, 8, 10, where glyphs were only partially erased, but no other instances of perfect glyphs existed to compare them with, I have let them alone, without attempting restoration. In short, I may have made some errors of eye, but I have guessed nothing. In a very few places I have restored glyphs totally erased, relying on the parallelism of the passages. Such are some of the Ahau-numbers in the upper sections of pages 2 to 11, and in the central sections on those pages, the initial pairs of glyphs on pages 15 to 18-a, b, c, the first columns of pages 19 and 20, and a few day-signs on pages 21, 23 and 24. These glyphs are all necessitated by their different series, and hence can cause no confusions; while it seemed advantageous to have them before the eye. A fair instance of the procedure is shown on page 3-b-1, 3. The temptation was strong to put the usual [Hieroglyph] glyph here as on all the other pages, but the slight variation in the lines left of glyph 3-b-3 forbade it. The restoration will further be found a little bolder on the type-cards than in the colored plates, where I have in general only endeavored to reproduce what could be seen actually present. The glyphs restored on the upper part of page 7 would seem hopeless at first sight; but they are well-known and common forms, and the characteristic traces shown on the photographs belong to these and to no others known. * * * * *