700 IIERSCHEL took the original observations of several remark- able nebulae in her brother's catalogue, and computed the places of his 2,500 nebulae. In 1798 she published her "Catalogue of Stars taken from Mr. Flamsteed's Observations, con- tained in the second volume of the Hiatoria Ccslestis, and not inserted in the British Cata- logue, with an index to point out every obser- vation in that volume belonging to the stars of the British Catalogue ; to which is added a collection of Errata that should be noticed in the same volume." This work was published at the expense of the royal society, and con- tained about 560 stars which had been omitted by the framers of the British catalogue. Af- ter her brother's death she returned to her native city. In 1828 she completed a cata- logue of the nebulae and stars observed by her brother, for which she received a gold medal from the astronomical society of London, and was elected an honorary member of it. III. Sir John Frederick William, an English as- tronomer and physicist, son of Sir William Herschel, born at Slough, March 7, 1792, died at Collingwood, near Hawkhurst, May 11, 1871. At Cambridge, where he graduated in 1813, he was distinguished for his mathemati- cal genius and his fondness for physical sci- ence. In 1820 he published his "Collection of Examples of the Application of the Calcu- lus to Finite Differences." About 1825 he be- gan his observations in sidereal astronomy, to which he chiefly devoted himself, partly in conjunction with Sir James South, and the re- sults of his observations for eight years were communicated to the royal astronomical soci- ety in a series of catalogues, the first appearing in 1825, for which he received the gold medal. In 1830 he published important measurements of 1,236 stars, which he found with his 20-foot reflector. In 1830 he wrote for the " Ency- clopaedia Metropolitana " a treatise on "Sound," and for the same work in 1831 a treatise on the " Theory of Light." In Lardner's " Cyclo- paedia " he published a " Preliminary Discourse on the Study of Natural Philosophy," and a "Treatise on Astronomy." About the same time he wrote several experimental essays on different branches of chemistry, magnetism, and optics. His great enterprise was his ex- pedition to the Cape of Good Hope, to take observations of the whole firmament of the southern hemisphere. Taking with him the same instruments (a 20-foot reflector with an 18J-inch aperture, and a 7-foot achromatic with a 5-inch aperture) which he had used in the northern hemisphere, that his results might be compared with his former ones, he arrived at the Cape, Jan. 15, 1834, and settled at Feldhuysen, about 6 m. from Table bay. He examined carefully and measured the dou- ble stars, clusters, and nebulae of the southern skies, and completed the wonderful "gauging of the heavens " which had been begun by his father. His observations lasted four years, and the entire expense was defrayed by him- self, though an ample indemnity was offered him by government. During his absence, in 1836, the royal astronomical society again voted him their gold medal, and on his return- honors were heaped upon him. The royal so- ciety proposed to make him their president, but he was unwilling to accept the office. In 1838, at the coronation of Queen Victoria, he was created a baronet. In 1839 he received the degree of D. C. L. from Oxford, and in 1842 he was elected lord rector of Marischal college, Aberdeen. In 1847 appeared in a large 4to volume his " Results of Astronomical Observa- tions made during the Years 1834-'8 at the Cape of Good Hope, being the completion of a Telescopic Survey of the whole surface of the Visible Heavens, commenced in 1825." This work, one of the most considerable and valu- able of our time, is divided into seven portions : 1, "Nebulae of the Southern Hemisphere;" 2, " The Double Stars of the Southern Hemi- sphere;" 3, "Astrometry, or the Numerical Expression of the Apparent Magnitudes of Stars;" 4, "The Distribution of Stars, and the Constitution of the Galaxy in the Southern Hemisphere;" 5, "Observations of Halley's Comet (as seen at the Cape toward the close of 1835), with Remarks on its Physical Condi- tion and that of Comets in general;" 6, "Ob- servations of the Satellites of Saturn;" 7, " Observations of Solar Spots." His residence at the Cape gave not only valuable additions to astronomy, but also to meteorology. He suggested the plan of taking simultaneous me- teorological observations at different places on given days, and embodied his views on the plan in his " Instructions for Making and Re- gistering Meteorological Observations at vari- ous Stations in Southern Africa " (1844). Be- fore going to the Cape of Good Hope he added 800 nebulas to the catalogue of his father, and on his return published a catalogue of 2,049 nebulae of the southern hemisphere and their positions, 500 of which were before entirely unknown. He also added, while at the Cape, 1,081 double stars, and in measuring the angles of positions and the distances of the stars from each other, found that many of them have very rapid orbital motions. He made many interesting observations on the milky way. "This remarkable belt," he says, "examined through a powerful telescope, is found (won- derful to relate) to consist entirely of stars scattered by millions, like glittering dust, on the black ground of the general heavens." Again, he conjectures, from his ingenious com- binations of photometric calculations, that if the stars in the great circle of the milky way, which he saw in his 20-foot reflecting tele- scope, were newly risen luminous cosmical bodies, it would require 2,000 years for a ray of their light to reach us. His observations on the brightness and the color of stars, on vari- able stars, on the sun's rays, on the atmo- spheric air, and on the Magellanic clouds, are all very valuable. Sir John Herschel did not
