Francesco Barozzi publishes Admirandum illud geometricum problema tredecim modis demonstratum quod docet duas lineas in eodem plano designare, a treatise on the construction of parallel lines.
Medicine
Timothy Bright publishes A Treatise of Melancholie; containing the causes thereof, & reasons of the strange effects it worketh in our minds and bodies: with the phisicke cure, and spirituall consolation... in London.
Physics
Galileo publishes La Billancetta, describing an accurate balance to weigh objects in air or water.[3]
Simon Stevin publishes De Beghinselen der Weeghconst in Leiden, discussing static forces; and De Beghinselen des Waterwichts, discussing the weight of water.