| ... As well as being the first printed Euclid, the Ratdolt edition is
| very important for further reasons too: the first work to use engraved
| geometrical diagrams, and it is printed in two colours (black and red,
| on the opening page at least). (Ratdolt went in for this -- his 1485
| Sacrobosco used five colours.)
It may be interesting to recall that, on the opening page, Ratdolt used
red ink only in the following sentence: "Preclarissimus liber elementorum
Euclidis perspicacissimi: in artem Geometrie incipit qua^foelicissime",
which may be seen as the 'title' of the work.
Another interesting issue is that the 1482 edition is regarded as the
first instance of the use of gold in *typography*!
Erhard Ratdolt is considered the first printer who introduced coloured
astronomical diagrams - indeed, and I have seen such diagrams in (kind
of) yellow, red, and black. But... John, are you certain that Ratdolt,
in his 1485 Sacrobosco, did use FIVE colours (inks)? I don't remember.
Best regards,
Julio