A water clock.
Giovanni Fontana (ca. 1395 – ca. 1455) was a fifteenth-century Venetian physician and engineer who portrayed himself as a magus. He was born in Venice in the 1390s and attended the University of Padua, where he received a his degree in arts in 1418 and his degree in medicine in 1421. University records list him as "Master John, son of Michael de la Fontana". 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. We have early works of his on water-clocks, sand-clocks and measurement. 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.
"Giovanni de la Fontana, engineer and magician" by Amelia Carolina Sparavigna
Giovanni de la Fontana [History of Computers...]