Hal'ley, EDMUND (1656-1742), an English astronomer and mathematician, born in London and educated at Saint Paul's School and at Queen's College, Oxford. He traveled extensively and made observations on important celestial phenomena, making a catalogue of the stars of the southern hemisphere. Newton's calculations of a comet's orbit were based partly on Halley's observations. Halley had charge of a voyage in the Pacific for the observation of the stars and was so successful that he was made a captain in the navy with half pay for life. In 1703 he became a professor of geometry at Oxford and ten years later became secretary of the Royal Society, which position he held until his death, devoting most of his time and study to the observation of the motions of the moon. A great many important discoveries are accredited to Halley, who is remembered as the first one to predict the return of a comet.