In his volume ‘Herschel and his Work,’ Mr James Sime writes: “To Herschel belongs the credit not merely of having suspected the revolution of sun around sun in the far-distant realms of space, but also of actually detecting that this was going on among the stars.” Throughout his career double stars were favourite objects of observation. The study of double stars was commenced by Herschel while a musician in Bath. Before his day, of course, double stars had been discovered and studied, but it was believed that the proximity of two stars was merely an optical accident, the brighter star being much nearer to us than the other. Herschel, at first sharing the general view, observed double stars in the hope of measuring their relative parallaxes; assuming one star to be much farther away from the Solar System than another, he attempted to measure the parallactic displacement of the brighter star relatively to the position of the fainter. “This,” he afterwards wrote, “introduced a new series of observations. I resolved to examine every star in the heavens with the utmost attention, that I might fix my observations upon those that would best answer my end. I took some pains to find out what double stars had been recorded by astronomers; but my situation permitted me not to consult extensive libraries, nor, indeed, was it very material; for as I intended to view the heavens myself, Nature, that great volume, appeared to me to contain the best catalogue.” Herschel, on January 10, 1782, submitted to the Royal Society a catalogue of 269 double stars: of these he himself discovered 227. In December 1784 he forwarded another catalogue, containing 434 stars. He soon found that he was unable to measure stellar parallax, and the idea dawned on him that the double stars were physically connected by the law of gravitation, though he made no announcement to that effect for many years. On July 1, 1802, Herschel informed the Royal Society that “casual situations will not account for the multiplied phenomena of double stars.... I shall soon communicate a series of observations, proving that many of them have already changed their situation in a progressive course, denoting a periodical revolution round each other.” In 1803 he showed that many stars were revolving round their centres of gravity, proving them, in his own words, to be “intimately held together by the bond of mutual attraction.” In other words, Herschel discovered that the law of gravitation prevailed in the Stellar Universe, as well as in our Solar System—that the law which Newton ascertained to prevail in the Solar System extended throughout the depth of space.