Giovanni Fontana, also known as Johannes de Fontana^[1] (ca. 1395 – ca. 1455) was a fifteenth-century Italian physician and engineer. He was born in Venice in the 1390s and attended the University of Padua, where he received his degree in arts in 1418 and his degree in medicine in 1421.^[2] University records list him as "Master John, son of Michael de la Fontana".^[3] His most famous promoter at the university was the scholastic Paul of Venice. He tells us that the Doge of Venice sent him to Brescia to deliver a message to the condottiere Francesco Carmagnola. He was also employed as the municipal physician by the city of Udine.

Fontana composed treatises on a diverse array of topics, including measurement of heights or depths by falling stones. We have early works of his on water-clocks (with wheels), sand-clocks and measurement. Fontana studied trigonometric measurements, mentioned in De trigono balistario, and through his own designed instrument, also explained in a larger treatise, however, apparently lost. He wrote a treatise on perspective, and showed it to the painter Jacopo Bellini. Grafton notes "Modern scholars often note that early engineers did not supply formal working drawings of their devices, but represented them in real time, functioning, in a way that did not give away their secrets but could appeal to patrons. Fontana, however, makes a superb exception to this rule. ... He drew not only male and female devils inspiring terror in real time by their fearsome appendages, but also the underlying mechanisms, which he laid out with the abstracting brilliance of a fifteenth-century Giacometti or Max Ernst. ... Fontana insisted that he was no magus. When witnesses at Padua exclaimed that a torpedo he had designed must run by diabolic power, he refuted them with contempt: the device was purely mechanical, as befitted a maker who was also a master of both medieval Archimedean statics and optics and of Renaissance engineering craft."^[4]

Fontana composed one of the earliest Renaissance technological treatises, Bellicorum instrumentorum liber. His machine book contains siege engines and fantastic inventions such as a magic lantern and a rocket-propelled bird, fish, and rabbit.^[5][6] Fontana also built a 4-wheeled "bike" with rope connected by gears.

Sparavigna 2013 notes, "He illustrates the designs of musical instruments such as mechanical organs (Puerilia) and masks, keys and locks, warships, double mirrors, stoves and surgical instruments. The code contains a part dedicated to hydraulic projects, public fountains, systems of water distribution, experiments with siphons, and also alembics and alchemical vessels for two or more liquids. According to [10,6], this manuscript shows that Fontana aimed to investigate a series of devices from ancient books of mathematicians and naturalists such as Archimedes, Heron, Philo, and even Ovid and Pliny the Elder, and the Arab writers, mainly from Al-Kindi, to his contemporary artists and craftsmen."^[4]

In the book Secretum de thesauro experimentorum ymaginationis hominum (Secret of the treasure-room of experiments in man's imagination), written ca. 1430, Fontana described mnemonic machines, written in his cypher.^[7] At least Bellicorum instrumentorum liber and this book used a cryptographic system, described as a simple, rational cipher, based on signs without letters or numbers.^[8] It has been suggested that some illustrations slightly resemble Voynich illustrations.^[9] During this time he also met with the Count of Carmagnola.^[4]

• Johannes Trithemius

• Bellicorum instrumentorum liber at the Bavarian State Library.
• Illustrations of Bellicorum instrumentorum liber at the Bavarian State Library
• Complete scans of Secretum de Thesauro BNF NAL 635