The enciphered manuscripts of Giovanni Fontana

There are only two known manuscripts from the relevant period which were written mainly in cipher. Both are works of the Italian humanist Giovanni Fontana: they are

Munich, Bayerische Staatsbibiliothek, Cod. Icon. 242
Bellicorum Instrumentorum Liber
Paris, Bibliotheque Nationale, Cod. Lat. Nouv. Acq. 635
Secretum de thesauro experimentorum ymaginationis hominum

The first contains proposals for machines, mainly with military purposes in mind: the second concerns mnemonic techniques including the use of mechanical devices. Both books are speculative and impractical in content and are illustrated with apparently fantastical pictures. The cipher is not the Voynich script but a simple substitution cipher. The two manuscripts are copies, not autographs, but the cipher is known from internal evidence to have been devised by Fontana. The chapter headings of the manuscripts are not in cipher: his editors suggest that the script served the dual purpose of concealment and intrigue. Both manuscripts are available in a beautiful modern edition:

Eugenio Battisti. Giuseppa Saccaro Battisti.
Le Macchine Ciffrate di Giovanni Fontana. Con la riproduzione del Cod. Icon. 242 della Bayerische Staatsbibliothek di Monaco di Baviera e la decrittazione di esso e del Cod. Lat. Nouv. Acq. 635 della Bibliotheque Nationale di Parigi.
Arcadia Edizioni. Milan. 1984

This particular Giovanni Fontana (there were several illustrious Italians of that name) was born before 1410 and died after 1454 and came from Padua. He was a product of Renaissance humanism, fascinated by new knowledge and the technological potential of experimental science, but in an age of great men he was not one of the greatest.

The mnemonic machines described in Secretum de Thesauro are curious, rather comical devices. (The first one consists of a peg board on which the holes bear numbers and the pegs bear letters as if you ‘memorised’ a word using a Travel Scrabble set.) However, some – not all – of the diagrams illustrating them slightly resemble Voynich illustrations. One of them deserves a detailed description.

It occupies the lower two thirds of f. 110r of the Paris manuscript. It consists of four concentric rings carefully drawn, probably with compasses. The circle inside the inner ring is hatched with lines radiating out from the centre. Each of the four rings is overlain with stars, or rather asterisks formed from three pen strokes: i.e. each circle is a ring of stars like the European flag. There are 45 stars in the outer ring, 32 in the next one, 26 in the next and 16 in the inner one. The diagram is labelled celum ecclexie. The accompanying text concerns the principle that mnemonic images should be dramatic and exaggerated; water should gush in floods, animals should be fierce and so on. The editors suggest that the picture is meant to be the vault of a church with an image of the heavenly spheres and the empyrean.

There exists a description of the Paris manuscript by H. Omont. Contrary to what he says, the book does not concern alchemy but artificial memory.