Sir George Darwin (1845-1912) was the second son and fifth child of Charles Darwin. After studying mathematics at Cambridge he read for the Bar, but soon returned to science and to Cambridge, where in 1883 he was appointed Plumian Professor of Astronomy and Experimental Philosophy. His work was concerned primarily with the effect of the sun and moon on tidal forces on Earth, and with the theoretical cosmogony which evolved from practical observation: he formulated the fission theory of the formation of the moon. These five volumes of collected papers are arranged by topic, and respectively cover oceanic tides and lunar disturbances of gravity, tidal friction and cosmogony, figures of equilibrium of rotating liquid and geophysical investigations, periodic orbits, and miscelleneous papers including his inaugural lecture, his lectures on George W. Hill's lunar theory, and a biographical memoir by his brother Sir Francis Darwin.