having constructed telescopes of great magnitude and power, he was induced to cultivate the loftier domain of sidereal astronomy. In 1825 he began to re-examine the numerous nebulæ and clusters of stars which had been discovered by his father, and described in the Philosophical Transactions; and in this great work he spent eight years, having finished it in 1832, and consigned its results in the Philosophical Transactions of that year. This catalogue contains 2306 nebulæ, &c., of which 525 were discovered by himself. While engaged in this work, he discovered between three and four thousand double stars which are described in the Memoirs of the Astronomical Society. These observations were made with an excellent Newtonian telescope 20 feet in focal length, and 18½ inches aperture; and having obtained, as he says, "a sufficient mastery over the instrument," he conceived the idea of employing it in the survey of the southern heavens. He accordingly left England with his family on the 13th November, 1833, and arrived at Cape Town on the 16th of January, 1834. Having settled at Feldhausen, about 142 feet above the sea and in E. long. 22° 46´ 9´´·11, and S. lat. 33° 58´ 56´´·59, he commenced that great series of valuable observations which were continued for four years, and the results of which were published at the expense of the late and present duke of Northumberland, in a work entitled "Results of Astronomical Observations made in 1834-35-36-37-38, at the Cape of Good Hope," &c. In this great work, which had he done nothing else would have placed him in the highest rank of astronomical discoverers, he treats of the nebulæ and clusters of stars in the southern hemisphere, amounting to 4015; of the double stars, amounting to 2095; of astrometry, or the measurement of the apparent magnitude of stars; of Halley's comet; of the satellites of Saturn; and of the solar spots.
On his return to England in 1838 Sir John was received with honours seldom conceded to men of science. The Astronomical Society had in his absence conferred upon him for the second time its gold medal. He had previously received from William IV. the Hanoverian order of K.H.; but, on the coronation of her majesty, he was created a baronet. In 1839 he was made a D.C.L. at Oxford. In 1845 he was appointed president of the British Association, and in 1848 president of the Royal Astronomical Society. In 1850 he was made master of the mint, an office which ill health obliged him to resign in 1855. Having been a corresponding member of the French Institute, he was elected in 1855, in the place of Gauss, one of the eight associates of the Academy of Sciences in that distinguished body. Beside the medals of the Astronomical Society, Sir John received the Copley medal in 1821 for his mathematical and physical paper in the Philosophical Transactions; and the same medal again in 1847 for his observations at the Cape. He received also the royal medals in 1833 for his investigation of the orbits of double stars, and the same medals again in 1840 for his valuable paper "On the Chemical Action of the Rays of the Solar Spectrum," on various substances—a paper which contains several new and interesting photographic processes. A supplement to this paper was published in 1843 entitled "On the Action of the Rays of the Solar Spectrum on Vegetable Colours, and on some new Photographic Processes." In addition to the works which we have mentioned, Sir John published in 1830 a valuable treatise on "Sound" in the Encyclopædia Metropolitana. In 1831 he contributed to Lardner's Encyclopædia, his celebrated "Preliminary Discourse on the Study of Natural Philosophy." In 1836 he published in the same work a treatise on astronomy, which appeared in 1849 in an enlarged and greatly improved form under the title of "Outlines of Astronomy." In the same year he edited the Manual of Scientific Inquiry, a work published by the authority of the admiralty, and prepared for the use of the navy by many of the most eminent scientific men of the present day. Sir John was also the author of the articles "Isoperimetrical Problems" and "Mathematics" in the Edinburgh Encyclopædia; and of the articles "Meteorology" and "Physical Geography" in the Encyclopædia Britannica, the two last of which have been published in separate volumes; and of various articles in the Edinburgh and Quarterly Review, which were published separately in 1857, with addresses and other pieces. To his other honours was added that of chevalier of the Prussian order "Pour la Merite," founded by Frederick the Great, and given on the recommendation of the Academy of Sciences at Berlin, of which Sir John was an honorary member. He was also an honorary or corresponding member of the academies of Petersburg, Vienna, Göttingen, Turin, Bologna, Brussels, Naples, Copenhagen, Stockholm, and almost all the other similar institutions in Europe and America.
We regret that our limited space prevents us from giving a fuller account of the scientific labours of Sir John Herschel. Few philosophers of his time attained to the same distinction. His mathematical acquirements and his discoveries in astronomy, optics, chemistry, and photography were of a very high order, and secured tor him a wide and well-earned reputation, while his various popular writings have greatly contributed to the diffusion of scientific knowledge among his countrymen. He died on the 11th of May, 1871.
HERSCHEL, William, a distinguished astronomer, was born at Hanover on the 15th November, 1738. He was one of five sons, who were all brought up, like their father, as professors of music. William, the second son. entered the band of the Hanoverian regiment of guards in 1752, and accompanied them to England in 1759. Soon after his arrival he was engaged by the earl of Darlington to instruct a military band for the militia then forming at Durham, and he subsequently established himself in the neighbourhood of Leeds, Pontefract, and Doncaster, where he taught music and conducted the public concerts and oratorios in these places. In 1766 he was appointed organist at Halifax, and soon afterwards he obtained the more lucrative situation of organist to the Octagon chapel at Bath. During his residence at Halifax he acquired an elementary knowledge of mathematics; and having studied astronomy in the popular writings of Ferguson, he was anxious to observe the celestial phenomena with which these works had made him acquainted. A small telescope, lent him by a friend, afforded him so much pleasure that he wished to possess one; and having failed to obtain it at a moderate price, he resolved to construct a reflecting telescope with his own hands. After surmounting the difficulties usually encountered in casting, grinding, and polishing the specula of reflecting telescopes, he completed in 1776 a Newtonian telescope five feet in focal length, which showed him the ring of Saturn, with the belts and satellites of Jupiter. He finished also several telescopes of the Gregorian forms; and in order to obtain a superior instrument, he executed eighty 20-feet, one hundred and fifty 10-feet, and two hundred 7-feet specula! Among the various stands which he contrived for these instruments, he was much pleased with his 7-feet Newtonian telescope stand, which he completed in 1778. In 1781 he began to construct a 30-feet aerial reflector, with a speculum three feet in diameter; and after executing a stand for it, the metal, which was too brittle, cracked in the cooling, his furnace erected in his own house gave way, and the metal ran into the fire.
His earliest regular observations were made between 1776 and 1780, on the periodical star in the neck of the Whale, and were published in the Philosophical Transactions for 1780. In 1781 he announced the discovery of a comet, which he afterwards found to be a planet situated beyond the orbit of Saturn. In imitation of Galileo, with his Medicæan stars, he gave the planet the courtly name of the Georgium Sidus, which was afterwards changed by astronomers to Herschel, and subsequently to Uranus, in conformity with astronomical nomenclature. This important discovery extended widely the reputation of our astronomer. George III. granted him a salary of £400 per annum, to enable him to devote his time to astronomy, and the learned academies of Europe followed the example of the Royal Society in admitting him into their body. He therefore established himself at Datchet, and subsequently at Slough, near Windsor, where for upwards of forty years he carried on that scrutiny of the heavens which has placed him high above all other astronomical discoverers.
His researches on double, triple, and multiple stars; on nebulæ and clusters of stars; on the motion of the solar system in space; and on the construction of the milky way, were vast accessions to sidereal astronomy, while his discoveries of new bodies and new phenomena within our own system were not less important additions to planetary astronomy.
On the 11th January, 1787, he discovered the second and fourth satellites of Uranus, and in 1790 and 1799 other four satellites, namely, the first, third, fifth, and sixth—all of them revolving round their primary from east to west, in a direction opposite to that of all the other planets, and in planes nearly at right angles to the plane of the ecliptic. Encouraged by his discoveries, he began, towards the end of 1785, to construct his
