HERSCHEL, Sir Frederick William (1738-1822), generally known as Sir William Herschel, one of the most illustrious of astronomers, was born at Hanover, November 15, 1738. His father was a musician employed as hautboy player in the Hanoverian guards. The family had migrated from Bohemia in the early part öf the 17th century, on account of religious troubles, they themselves being Protestants. Herschel’s earlier education was necessarily of a very limited character, chiefly owing to the troubles in which his country at that time was involved; but, being at all times an indomitable student, he, by his own exertions, more than repaired this deficiency of his youth. He became a very skilful musician, both theoretical and practical; while his attainments as a self-taught mathematician were fully adequate to the prosecution of those branches of astronomy which, by his labours and his genius, he so eminently advanced and adorned. Whatever he did he did methodically and thoroughly; and in this methodical thoroughness lay the secret of what Arago very properly terms his astonishing scientific success.

In 1755, at the age of seventeen, he joined the band of the Hanoverian guards, and with his detachment visited England, accompanied by his father and eldest brother; in the following year he returned to his native country, but two years later, impelled by the troubles that surrounded him, he finally quitted Hanover to seek his fortunes in England. As might have been expected, the earlier part of his career in his adopted country was attended with formidable difficulties and much privation. We find him engaged in several towns in the north of England as organist and teacher of music, but these were occupations not attended with any lucrative results. In 1766 the tide of his fortunes began to flow, inasmuch as he obtained the appointment of organist to the Octagon Chapel in Bath, at that time the resort of the wealth and fashion of the city, and of its numerous distinguished visitors.

The next five or six years of his life were spent in establishing his reputation as a musician, and he thereby eventually became the leading musical authority in the place, and the director of all the chief public musical entertainments. His circumstances having thus become easier, he revisited Hanover for the purpose of bringing back with him his sister Caroline, with the view of her rendering him such services as she could in his multifarious undertakings. She arrived in Bath with her brother in August 1772, being at that time in her twenty-third year. She thus describes her brother’s life soon after her arrival :—“He used to retire to bed with a bason of milk or a glass of water, with Smith’s Harmonics and Ferguson’s Astronomy, &c., and so went to sleep buried under his favourite authors; and his first thoughts on waking were how to obtain instruments for viewing those objects himself of which he had been reading.” It is not without significance that we find him thus reading Smith’s Harmonics; to that study loyalty to his profession would impel him; as a reward for his thoroughness this led him to Smith’s Optics ; and this, by a natural sequence, again led him to astronomy, for the purposes of which the chief optical instruments were devised. It was in this way that he was introduced to the writings of Ferguson and Keill, and subsequently to those of Lalande, whereby he was educating himself for an astronomer and for undying fame. In those days telescopes were very rare, very expensive, and not very efficient, for the Dollonds had not as yet perfected even their beautiful little achromatics of 2f inches aperture. So Herschel was obliged to content himself with hiring a small Gregorian reflector of about 2 inches aperture, which he had seen exposed for loan in a tradesman’s shop. Not satisfied with this implement, he procured a small lens of about 18 feet focal length, and set his sister to work on a pasteboard tube of that length, so as to make him a telescope. A tube of this construction naturally bent, and it was useless for all purposes but for the determined eyes of William Herschel. This material was soon displaced for tin, and thus a sorry sort of vision was obtained of Jupiter and Saturn and the moon. He then sought for a reflector of much larger dimensions from artists in London. No such instrument, however, was for sale; and the terms demanded for the construction of a reflecting telescope of 5 or 6 feet focal length he regarded as too exorbitant even for the gratification of such desires as his own. So he was driven to the only alternative that remained; he must construct a large telescope for himself. His first step in this direction was to purchase the debris of an amateur’s implements for grinding and polishing small mirrors; and thus, by slow degrees, and by indomitable perseverance, he in 1774 had, as he says, the satisfaction of viewing the heavens with a Newtonian telescope of 6 feet focal length constructed by his own hands. But he was not a man to be contented with viewing the heavens as a mere star-gazer; on the contrary, he had from the very first conceived the gigantic project and the hope of surveying the entire heavens, and, if possible, of ascertaining the plan of their general structure on a settled and systematic mode of procedure, if only he could but provide himself with adequate instrumental means. With this view he, his brother, and his sister toiled for many years at the grinding and polishing of hundreds of specula, always retaining the best, and recasting the others, until the best of the previous performances had been surpassed. This was the work of the daylight in those seasons of the year when the fashionable visitors of Bath had quitted the place, and had thus freed the family from professional duties. After 1774 every available hour of the night was devoted to the long-hoped-for scrutiny of the skies. In those days no machinery had been invented for the construction of telescopic mirrors; the man who had the hardihood to undertake the polishing doomed himself to walk leisurely and uniformly round an upright post for many hours, without removing his hands from the mirror, until his work was done. On these occasions Herschel received his food from the hands of his faithful sister. But his reward was nigh.

In May 1780 his first two papers containing some of the results of his astronomical observations during the last six years were communicated to the Royal Society through the influential introduction of Dr Watson. Herschel had made the acquaintance of this excellent man and skilful physician in a characteristic manner. In order to obtain a sight of the moon the astronomer had taken his telescope into the street opposite his house; the physician happening to pass at the time, and seeing his eye removed for a moment from the instrument, requested permission to take his place. The mutual courtesies and intelligent conversation which ensued soon ripened this casual acquaintance into a solid and enduring regard.

The subject of this first memoir was the varying lustre of several of the stars, and especially that of Mira in the constellation of Cetus. It had been long known to fade in brightness from nearly that of a star of the first magnitude down to invisibility in such telescopes as then existed. Herschel had examined it, and many other variable stars, for himself; it was not, however, a simple or isolated phenomenon that engaged his attention; but, regarding the stars as so many suns, he examined stellar phenomena as possibly leading him to some intelligent conception of what might be occurring in our own sun. The sun, he knew, rotated on its axis, and he knew that dark spots often exist on its photosphere; the questions that he put to himself were—Are there dark spots also on these variable stars Ido the stars also rotate on their axes I or are they sometimes partially eclipsed by the intervention of some opaque and invisible bodies? And then he asked himself— What are these singular spots upon the sun? and have they any practical relation to us, the inhabitants of this planet? To these questions he applied his telescopes and his thoughts; and as light from time to time dawned upon his apprehension, he communicated the results to the Royal Society in no less than six memoirs, occupying very many pages in the Philosophical Transactions, and extending in date from 1780 to 1801. It was in the latter year that these remarkable papers culminated in the inquiry whether any relation could be traced in the recurrence of sun-spots, regarded as evidences of solar activity (allied to volcanic), and the varying seasons of our planet, as exhibited by the varying price of corn? Herschel’s solution of the question was scarcely final, and the question has recently cropped up again, with more than a renewal of its former interest.

In the following year (1781) he communicated to the Royal Society the first of a series of papers containing the results of his telescopic inquiries in relation to the rotation of the planets and of their several satellites. The object which he had in view was not so much to ascertain the velocities or times of their rotation, as rather to discover whether those rotations are strictly uniform. From the result he expected to gather, by analogy, the probability of an alteration in the length of our own day. These inquiries occupy the greater part of seven memoirs extending from 1781 to 1797. In the course of these telescopic observations he lighted on the curious appearance of a white spot near to each of the poles of the planet Mars. On investigating the inclination of its axis to the plane of its orbit, and finding that it closely resembled that of our earth, he concluded that its changes of climate also would resemble our own, and that these white patches were probably polar snow. Modern investigations have confirmed his conclusion. He also discovered that, as far as his observations extended, the times of the rotations of the various satellites round their axes are in analogy with our own moon, viz., equal to the times of their revolution round their primaries. Here again we observe that his discoveries arise out of the complete and systematic and comprehensive nature of the investigation in which he is engaged. Nothing with such a man is accidental.

In the same year (1781) Herschel made a discovery which, as we shall see, soon completely altered the character of his professional life. In the course of his systematic examination of the heavens with a view to the discovery of the plan of their construction, he lighted on an object which at first he supposed to be a comet, but which, by its subsequent motions and appearance, turned out to be a new planet, moving outside of the orbit of Saturn. To this planet he in due time assigned the name of Georgium Sidus; but this name has by general consent been laid aside in favour of Uranus. It was discovered with a favourite 7-foot reflector having an aperture of G√ inches; subsequently, when he had provided himself with a much more powerful telescope, of 20 feet focal length, he discovered what he believed to be no less than six satellites. Modern observations have shorn this gloomy planet of four of these supposed attendants, but at the same time have added two others apparently not observed by Herschel. No less than seven memoirs on the subject were communicated by him te the Royal Society, extending from the date of the discovery in 1781 to 1815. There is a peculiarity worthy of notice in Herschel’s mode of observation which led to the discovery of this planet. He had observed that the spurious diameters of stars are not much affected by increasing the magnifying powers, but that the case is different with other celestial objects; hence if anything in his telescopic field attracted his notice by peculiarity of appearance, he immediately varied the magnifying power in order to decide the nature of the object. Thus Uranus was discovered; and had a similar method been applied to Neptune, that planet would have been discovered at Cambridge some months before it was recognized at Berlin.

We now come to the commencement of Herschel’s most important series of observations, culminating in what ought probably to be regarded as his most capital discovery. A material part of the task which he had set himself as the work of his astronomical life embraced the determination of the relative distances of the stars from our sun and from each other. Now, in the course of his scrutiny of the heavens, he had observed many stars in apparently very close contiguity, but often greatly differing in their relative brightness. He concluded that, on the average, the brighter star would be the nearer to us, and the smaller enormously more distant. He considered that an astronomer on the earth, in consequence of its immense orbital displacement of some 180 millions of miles every six months, would see such a pair of stars under different perspective aspects; and this variety of perspective aspect observed and measured would, he thought, lead to an approximate determination of their distance. With this view he mapped down the places and aspects of all the double stars that he met with, and communicated in 1782 and 1785 very extensive catalogues of the results. Indeed, the very last scientific memoir that he ever wrote, sent to the Royal Astronomical Society in the year 1822, at the time when he was its first president and already in the eighty-fourth year of his age, related to these investigations. In the first of these memoirs he throws out the hint that these apparently contiguous stars must, if constituted after the material laws of our solar system, circulate round each other through the effects of gravitation; but he significantly adds that the time had not yet arrived for settling the question. Thus the philosopher abides his time in patience and confidence, and a dozen years afterwards (1793) he remeasures the relative positions of many of these contiguous pairs, and we may conceive what his feelings must have been at finding the verification of his prediction. For he found that some of these stars had circulated round each other, after the manner required by the laws of gravitation. Thus Herschel had demonstrated the action of the same mechanical laws among the distant members of the starry firmament which bind together the harmonious motions of our solar system. This sublime discovery would of itself suffice to immortalize his memory in the respectful homage of all future races of intelligent men. If only Herschel had lived long enough to learn the approximate distances of some of these binary combinations, he would at once have been able to calculate their masses when compared with that of our own sun; and thus, knowing, as we now do, that these stars in their weights are strictly comparable with the weight of our own sun, he would have found another of his analogical conjectures realized.

In the year 1782, in consequence of his fame, Herschel was invited to Windsor by George HL, and then accepted the offer made by the king to become his private astronomer, and henceforth devote himself wholly to a scientific career. The salary offered and accepted was £200 per annum, to which an addition of £50 per annum was subsequently made for the astronomical assistance of his faithful sister. Dr Watson, to whom alone the amount of this salary was mentioned, made the natural remark, “Never before was honour purchased by a monarch at so cheap a rate.” In this way the great philosophical astronomer removed from Bath first to Datchet and soon afterwards permanently to Slough, within the easy access of his royal patron at Windsor.

The old pursuits at Bath were soon resumed at Slough, but with renewed vigour and without the old professional interruptions. The greater part, in fact, of the papers already referred to are dated from Datchet and Slough, for the magnificent astronomical speculations in which he was engaged, though for the most part conceived in the earlier portion of his philosophical career, required years of patient observation before they could be fully examined and realized.

It was at Slough in 1783 that he wrote his first memorable paper on the “Motion of the Solar System in Space,” —a sublime speculation, yet through his genius realized by considerations of the utmost simplicity. He returned to the same subject with fuller details in 1805. It was also after his removal to Slough that he published his first memoir containing his speculative ideas on the construction of the heavens, which from the first had been the chief aim of his toils both of mind and body. In a long series of remarkable papers, addressed as usual to the Royal Society, and extending from the year 1784 to 1818, when he was eighty years of age, he demonstrated the fact that our sun is a star situated not far from the bifurcation of the Milky Way, and that all the stars visible to us lie more or less in clusters scattered throughout a comparatively thin stratum, but in the other two dimensions stretching immeasurably further into space. At one time he imagined that his powerful instruments had pierced through this stellar stratum of the Milky Way, and that he had approximately determined the form of some of its boundaries. In the last of his memoirs he had convinced himself of his error, and he admitted that to his telescopes our stratum of stars is “fathomless.” Over this stratum of stars and their planetary attendants, the whole being in ceaseless motion round some common centre of gravity as the resultant point of the combined gravitation, Herschel discovered on either side a canopy of discrete nebulous masses, from the condensation of at least a part of which the whole stellar universe had been formed,—a magnificent conception, pursued with a force of genius and put to the practical test of observation with an industry almost incredible. It was the work of a single mind, carried to its termination with no assistance beyond that of a loyal sister, almost as remarkable a personage as himself.

Hitherto we have said nothing about that grand reflecting telescope, of 40 feet focal length and 4 feet aperture, which is too often regarded as the chief effort of his genius and his perseverance. The full description of this celebrated instrument will be found in the 85th volume of the Transactions of the Royal Society. Gigantic as it really was, we are disposed to regard it as among the least of his great works. On the day that it was finished (August 28, 1789) Herschel saw at the first view, in a grandeur not witnessed before, the Saturnian system with all its six satellites, five of which had been discovered long before by Huygens or Cassini, while the sixth, latterly named Enceladus, he had, two years before, sighted by glimpses in his exquisite little telescope of 6⅜ inches aperture, but now saw in unmistakable brightness with the towering giant he had just completed. On the 17th of September he discovered a seventh, which proved to be the nearest of all the satellites of Saturn. It has since that time received the name of Mimas. It is somewhat remarkable that, notwithstanding his long and repeated scrutinies of this planet, the eighth satellite, Hyperion, and the crape ring should have escaped him.

Herschel married the widow of Mr John Pitt, a wealthy London merchant, on May 8, 1788, by whom he had an only son, John Frederick William. The prince regent conferred a Hanoverian knighthood upon him in 1816. But a far more valued and less tardy distinction was the Copley medal assigned to him by his associates in the Royal Society in 1781.

He died at Slough on August 25, 1822, in the eightyfourth year of his age, and was buried under the tower of St Laurence Church, Upton, within a few hundred yards of the old site of the 40-foot telescope. A mural tablet on the wall of the church bears a Latin inscription from the pen of the late Dr Goodall, provost of Eton College. A collected edition of bis astronomical memoirs would speak of his genius in unmistakable language; but this has not yet been published.

HERSCHEL, Sir John Frederick William, Bart. (1792-1871), the illustrious astronomer, the only son of Sir F. William Herschel, was born at Slough, Bucks, in the year 1792. His early home was a singular one, and eminently adapted to nurture into greatness any child born, as he was, with natural gifts capable of wide development. The examples about him were those of silent but ceaseless industry, busied about things which, at the first view, seemed to have no apparent connexion with the world outside the walls of his abode, but which, at a mature period of his life, he, with rare eloquence, taught his countrymen to appreciate as foremost among those influences which satisfy and exalt the nobler instincts of our nature.

His scholastic education commenced at Eton, but maternal fears or prejudices soon removed him to the house of a private tutor. Thence, at the early age of seventeen, he was sent to St John’s College, Cambridge, and the form and method of the mathematical instruction he there received exercised a material influence on the whole complexion of his scientific career. In due time the young student acquired the highest academical distinction of his year, graduating as senior wrangler. It was during his undergraduateship that he and two of his fellow-students who subsequently attained to very high eminence in their respective careers of life, Dean Peacock and Mr Babbage, entered into a sort of moral compact that they would “do their best to leave the world wiser than they found it,”—a compact loyally and successfully carried out by all three to the end. As a commencement of this laudable attempt we find Herschel associated with these two friends in the production of a work on the differential calculus, and on cognate branches of mathematical science, which changed the whole style and aspect of mathematical learning in England, and brought it up to the level of the Continental methods. Two or three memoirs communicated to the Royal Society on new applications of mathematical analysis at once placed him in the front rank of the cultivators of this branch of knowledge. Of these his father had the gratification of introducing the first, but the others were presented in his own right as a fellow.

His first intention had been to study for the bar, and with this view he left the university, and placed himself under the guidance of an eminent special pleader of that day. Probably this -temporary choice of a profession arose from the extraordinary success which for some time had attended the efforts of so many eminent Cambridge mathematicians in legal pursuits. Be that as it may, an early acquaintance with Dr Wollaston in London soon changed the direction of his studies. In 1820, assisted by his father, he completed a mirror of 18 inches diameter and 20 feet focal length, for a reflecting telescope. This, subsequently improved by his own hands, became the instrument which enabled him to effect the astronomical observations which, more than any other of his great works, form the basis of his fame. In 1821-23 we find him associated with Mr South in the re-examination of his father’s double stars, by the aid of an achromatic telescope and other appliances, the like of which for excellence and power had not hitherto been collected. For this work in 1826 he received the recognition of the Astronomical Society by the award of their gold medal; the French Institute also presented him with the Lalande medal for the same contribution to astronomical science. It ought also to be mentioned that in 1821 the Royal Society had presented him with the Copley medal for his mathematical contributions to their Transactions. From 1824 to 1827 he held the distinguished and responsible post of secretary to that society. In 1827 he was elected to the chair of the Astronomical Society, which office he also filled on two subsequent occasions. In the course of the discharge of his important offices in the last-named society he ennobled its literature by his memorable presidential addresses and obituary notices of deceased fellows, which, it is not too much to say, are, by their combination of eloquence and wisdom, the chief adornments of their printed memoirs. In 1831 the honour of knighthood was conferred on him by William IV., and two years later he again received the recognition of the Royal Society by the award of one of their medals for his memoir “On the Investigation of the Orbits of Revolving Double Stars.” There is a significance in this award; the father had been the original discoverer of the extension of gravitation to the remotest boundaries of the visible universe, and the son had now put the crowning stone to this edifice of discovery by the invention of a graphical method whereby the eye could as it w ere see the two component stars of the binary system revolving before it, after the regularity of the Newtonian law.

Before the end of the year 1833, being then about forty years of age, Sir John Herschel had re-examined all his father’s discoveries of double stars and nebulae, and had added many similar bodies to his own list; this alone constituted a gigantic work even for the lifetime of any astronomer in that day. For it should be remembered that the astronomer was not as yet provided with those curious and valuable automatic contrivances for observing and for recording observations which at present most materially abridge the labour and increase the accuracy of astronomical work such as that in which Sir John had been engaged. And he had no assistant. Equatorial clocks for turning the telescope, electrical chronographs for recording the times of the phenomena observed, were at that date unknown.

His scientific life now entered another and very characteristic phase. The bias of his mind, as he subsequently was wont to declare, was towards chemistry and the phenomena of light, rather than towards astronomy. Indeed, very shortly after taking his academical degree at Cambridge, he proposed himself as a candidate for the vacant chair of chemistry in that university; but, as he said with some humour, the result of the election was that of the votes he had a glorious minority of one. In fact Herschel had become an astronomer from a sense of duty, just as his father had become one by fascination and fixed resolve; hence it was by filial loyalty to his father’s memory that he was now impelled to undertake the completion of that work which at Slough had been so grandly commenced. William Herschel had explored the northern heavens; John Herschel determined to explore the heavens of the south, as well as re-explore the north. “I resolved,” he said, “to attempt the completion of a survey of the whole surface of the heavens; and for this purpose to transport into the other hemisphere the same instrument which had been employed in this, so as to give a unity to the results of both portions of the survey, and to render them comparable with each other.” In accordance with this resolution, he and his family embarked for the Cape on the 13th November 1833; they arrived in Table Bay on the 15th January 1834; and proceedings, he says, “were pushed forward with such effect that on the 22d of February I was enabled to gratify my curiosity by a view of κ Crucis, the nebula about η Argus, and some other remarkable objects in the 20-foot reflector, and on the night of the 4th of March to commence a regular course of sweeping.”

To give an adequate description of the vast mass of labour completed during the next four busy years of his life at Feldhausen would require the transcription of a considerable portion of the Cape Observations, a volume which probably is not surpassed in varied interest or astronomical importance by any scientific work in existence; although it might perhaps be equalled by a judicious selection from Sir William’s “Memoirs,” now scattered in some thirty volumes of the Philosophical Transactions. It was published, at the sole expense of the late duke of Northumberland, but not till 1847, nine years after the author’s return to England, for the very cogent reasons assigned by himself :—‘ ‘ The whole of the observations, as well as the entire work of reducing, arranging, and preparing them for the press, have been executed by myself.” There are 164 pages of catalogues of southern nebulae and clusters of stars. There are then careful and elaborate drawings of the southern appearance of the great nebula in Orion, and of the region surrounding the remarkable star of Argo. The labour and the thought bestowed upon some of these objects are almost incredible; several months were well spent upon a minute spot in the heavens containing 1216 stars, but which an ordinary spangle, held at a distance of an arm’s length, would eclipse. These catalogues and charts being completed, he proceeds to discuss their significance, wlιich in the eyes of science possesses an absorbing interest. He confirms his father’s hypothesis that these wonderful masses of glowing vapours are not irregularly scattered, and without apparent law, hither and thither in the visible heavens, but are collected in a sort of canopy, whose vertex is at the pole of that vast stratum of stars in which our solar system finds its position,—buried in it, as he supposes, at a depth not greater than that of the average distance from us of an eleventh magnitude star. Then follows his catalogue of the relative positions and magnitudes of the southern double stars. And he applies to one of them, γ Virginis, that beautiful graphical method invented by himself, whereby he determines the orbit of the two components round each other; and he had the satisfaction of witnessing with his own eyes the fulfilment of a prediction he had made some years before, viz., that the two stars would, in the course of their orbital movements, appear to close up into a single star, inseparable by any telescopic power. The double stars and their stately revolutions and lustrous colours dismissed, in the next chapter he proceeds to describe the observations which he had made on their varying and relative brightness. It has been already detailed how his father commenced his scientific career by similar observations on the varying magnitudes of many stars, and how his remarks culminated years afterwards in the question whether the variation of the lustre of our sun, by the presence or absence of sun spots, affected our harvests and the price of corn. The son carries his speculations backwards to a still more philosophical depth. The variation from time to time, he remarks, in the lustre of our sun, to the extent of half a magnitude, would account for those strange alternations of a semi-arctic and semi-tropical climate which geological researches have disclosed as having occurred in various regions of our globe.

Herschel returned to his English home in the spring of 1838. As was natural and honourable to all concerned, he was welcomed with an enthusiastic greeting. By the queen at her coronation he was created a baronet; and, what to him was better than all such rewards, other men caught the contagion of his example, and laboured in fields similar to his own, with an adequate portion of his success. In particular Mr Lassell transported a telescope as large as the celebrated Herschelian telescope to Malta, where with excellent results he “minded the heavens” for the space of four years. He was rewarded there, and at his own English residence near Liverpool, by the discovery of new satellites of Saturn and of Uranus, constituting what Sir John Herschel, animated by a fraternal sympathy, well called an epoch in astronomy. Mr De La Rue also, at Islington and at Cranford, followed zealously and successfully in the wake of the same infectious enthusiasm.

Herschel was a highly accomplished chemist. His discovery of the solvent power of hyposulphite of soda on the otherwise insoluble salts of silver, in 1819, exercised a most important influence on the practical applications of photography twenty years afterwards; and in 1839, the natal era of that valuable art, he, independently of Mr Fox Talbot, had discovered the means of taking and multiplying photographic pictures, and early in the spring of that year exhibited more than twenty photographic pictures to the Royal Society, including one of the old 40-foot telescope. He was the first person to introduce the now well-known terms positive and negative in photographic images, and to deposit upon glass a sensitized film for the reception of the picture. He also paved the way for Professor Stokes’s important discovery of the change which luminous waves may suffer in their period of oscillation, by his addition of the lavender rays to the spectrum, and by his announcement of “epipolic dispersion,” as exhibited by sulphate of quinine. Several other important and successful researches of his, connected with the undulatory theory of light, are scattered through the pages of his treatise on “Light” published in the Encyclopaedia Metropolitana.

To the other varied accomplishments of his gifted mind we must add the graces of a deep poetic feeling. Perhaps no man can become a truly great mathematician or great philosopher, if unendowed with the versatile powers of the imagination. John Herschel possessed this endowment to a large extent; and he had reserved for himself as a solace and enjoyment in old age the translation of the Iliad into verse. He had at an earlier period of life translated in a similar manner Schiller’s Walk. But the main work of his declining years was the collection of all his father’s catalogues, combined with his own observations and those of other astronomers of nebulae and double stars, each into a single volume. He lived to complete the former, and to present it to the Royal Society, who have published it in a separate form in the Philosophical Transactions. The latter work he had not fully completed at his death; but he bequeathed as much of it as was finished to the Astronomical Society. That society has printed a portion of it, which serves as an index to the observations of various astronomers on double stars up to the year 1866.

A complete list of his various contributions to learned societies will be found in the Royal Society’s great catalogue, and from them may be gathered most of the records of his busy scientific life. Sir John Herschel met with an amount of public recognition which was unusual in the time of his illustrious father. Naturally he was a member of almost every important learned society in both hemispheres. For five years he held the office of master of the mint, the same appointment which, more than a century before, had been occupied by Sir Isaac Newton; his friends also offered to propose him as president of the Royal Society and again as a member of parliament for the university of Cambridge, but neither office was withiu the scope of his own desires.

Iu private life Sir John Herschel was a firm and most active friend; he had no jealousies; he avoided all scientific feuds; he gladly accorded a helping hand to those who consulted him in scientific difficulties; he never discouraged, and still less disparaged, men younger than or inferior to himself; he was pleased when his own work was appreciated, but that was never an object of his solicitude: it was said of him by a discriminating critic, and without extravagance, that “his was a life full of the serenity of the sage and the docile innocence of a child.”

He died at Collingwood, his residence near Hawkhurst in Kent, May 11, 1871, in the seventy-ninth year of his age, and his remains are interred in Westminster Abbey close to the grave of Sir Isaac Newton.

Sir John Herschel, independently of the labours connected with his Cape Observations, was the author of several books, one of which at least, On the Study of Natural Philosophy (1830), possesses an interest which no future advances of the subjects on which he wrote can obliterate from the attention of thoughtful men in any age. In 1849 came the Outlines of Astronomy, of which it is enough to say that, notwithstanding the obvious disadvantage arising from the practice of stereotyping text-books which relate to progressive sciences, there is no more instructive volume extant on the subject of which it treats. His articles, “Meteorology,” “Physical Geography,” and ‘ ‘ Telescope,” contributed to the 8th edition of the Encyclopoedia Britannica, were afterwards published separately. There is also another very valuable little book, which originated from a happy peculiarity of Sir John Herschel’s dignified simplicity and truthfulness of mind. When he was at the Cape he more than once assisted in the attempts there made to diffuse a love of knowledge. among men not engaged in literary pursuits. In one of his addresses he, with a kindly and far-seeing wisdom, told his audience that the advance of a nation’s intelligence or a nation’s fame did not depend upon a few successful philosophers toiling in their lonely studies, and gathering great reputations for their learning or their discoveries, but that a nation’s progress rather lay in the diffusion of their knowledge among the masses of the population. Acting practically on this principle, he, on his return to England, published, in Good Words and elsewhere, a series of papers on interesting points of natural philosophy, which have since been collected in a volume called Familiar Lectures on Scientific Subjects. None but a deep thinking philosopher could have written this book; none but a clear thinking master of his subjects could have made it what it is, enticingly intelligible. Another volume of his, not so widely known to the public as any of the above works, is his Collected Addresses, in which he is seen in his happiest and most instructive mood, walking, as it were, at liberty among sympathizing associates, in his own fields, and enamoured of their beauties. ∙(C∙ P∙)