Crossreference with Mappa Clavicula: An introduction to one of the sets of manuscripts best known under its lesser-known title of the Mappa Clavicula. Johnson had access to at least one no longer in existence, a victim, it seems of one of the World Wars. They were effectively the only known collections of technological recipes known written and rewritten between 400 and @800 CE, showing a continuation of the collections of believed-scientific methods, mainly for artists, especially those working with gold (or pretending to, anyway...) between the 700s and the 1100s. The book would gain the absurd (a series of water or steam-driven toys resembling the works of Hero (worthless as they reffered to missing drawings), a short section on setting fire by arrow, even proof that the candy called taffy in the US dates back to the pre-Christian Millennium! In my opinion, the Mss. demonstrate a continuation of the Greco-Roman formulary and a rather lighter "dark ages". It also demonstrated the poor qualities of many a medieval scribe, who added what seems like a ton of dross to the small bits of gold every time they recopied something. Johnson worked with some of the earliest known copies and surviving fragment.
The latest and largest Mss., the Phillips-Corning Mss is due to go on line in 2011 - it, and the second-latest ,were translated in the early 1970s by Cyril S. Smith and still available in reprint from the Americen Philosophical Soc. Philadelphia, Pa., New Series V64 Pt.4.