Galileo's later astronomical discoveries of Saturn's ring and the phases of Venus is taken from the preface of this work — (kepler's Dioptrics; Augs burg, In 1612 Galileo published a series of observations of solar spots, and in 1618 some observations of three comets. There exist also long series of minute observations of Jupiter and his satellites, continued to November 1619. — (galileo's Works Florence.