This book is part of a four-volume edition of the works of the Italian astronomer and engineer Galileo. It was published at Padua in 1744.

Galileo is perhaps best known for his astronomical observations, most notably his confirmation and support of Copernicus’s discovery that the Earth revolved around the Sun. Using a refracting telescope of his own design, Galileo also made the first observations of three of the four largest moons of the planet Jupiter (now known as the Galilean moons: Io, Europa, Ganymede and Callisto), the rings of Saturn, sunspots and the phases of Venus.