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+The Project Gutenberg EBook of Sir William Herschel: His Life and Works, by
+Edward Singleton Holden
+
+This eBook is for the use of anyone anywhere at no cost and with
+almost no restrictions whatsoever.  You may copy it, give it away or
+re-use it under the terms of the Project Gutenberg License included
+with this eBook or online at www.gutenberg.org
+
+
+Title: Sir William Herschel: His Life and Works
+
+Author: Edward Singleton Holden
+
+Release Date: June 3, 2009 [EBook #29031]
+
+Language: English
+
+Character set encoding: ASCII
+
+*** START OF THIS PROJECT GUTENBERG EBOOK SIR WILLIAM HERSCHEL ***
+
+
+
+
+Produced by Bryan Ness, Eric Hutton and the Online
+Distributed Proofreading Team at https://www.pgdp.net (This
+book was produced from scanned images of public domain
+material from the Google Print project.)
+
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+
+
+
+
+
+
+SIR WILLIAM HERSCHEL
+
+HIS LIFE AND WORKS
+
+
+
+
+[Illustration: Sir William Herschel]
+
+SIR WILLIAM HERSCHEL
+
+
+HIS LIFE AND WORKS
+
+BY
+
+EDWARD S. HOLDEN
+
+UNITED STATES NAVAL OBSERVATORY, WASHINGTON
+
+[Illustration: Coelis Exploratis]
+
+
+
+NEW YORK
+CHARLES SCRIBNER'S SONS
+743 AND 745 BROADWAY
+1881
+
+
+
+COPYRIGHT, 1880,
+BY CHARLES SCRIBNER'S SONS.
+
+
+
+PRESS OF J. J. LITTLE & CO.,
+
+NOS. 10 TO 20 ASTOR PLACE, NEW YORK.
+
+
+
+
+Please see the end of the text for TRANSCRIBER'S NOTES
+
+
+
+
+PREFACE.
+
+
+In the following account of the life and works of Sir WILLIAM HERSCHEL,
+I have been obliged to depend strictly upon data already in print--the
+_Memoir_ of his sister, his own scientific writings and the memoirs and
+diaries of his cotemporaries. The review of his published works will, I
+trust, be of use. It is based upon a careful study of all his papers in
+the _Philosophical Transactions_ and elsewhere.
+
+A life of HERSCHEL which shall be satisfactory in every particular can
+only be written after a full examination of the materials which are
+preserved at the family seat in England; but as two generations have
+passed since his death, and as no biography yet exists which approaches
+to completeness, no apology seems to me to be needed for a
+conscientious attempt to make the best use of the scanty material which
+we do possess.
+
+This study will, I trust, serve to exhibit so much of his life as
+belongs to the whole public. His private life belongs to his family,
+until the time is come to let the world know more of the greatest of
+practical astronomers and of the inner life of one of its most profound
+philosophers,--of a great and ardent mind, whose achievements are and
+will remain the glory of England.
+
+
+
+
+CONTENTS.
+
+                                                  PAGE
+CHAPTER I.
+
+EARLY YEARS; 1738-1772,                              1
+
+
+CHAPTER II.
+
+LIFE IN BATH; 1772-1782,                            33
+
+
+CHAPTER III.
+
+LIFE AT DATCHET, CLAY HALL, AND SLOUGH; 1782-1822,  68
+
+
+CHAPTER IV.
+
+REVIEW OF THE SCIENTIFIC LABORS OF HERSCHEL,       118
+
+
+BIBLIOGRAPHY,                                      215
+
+
+INDEX OF NAMES,                                    235
+
+
+
+
+LIFE AND WORKS
+
+OF
+
+WILLIAM HERSCHEL.
+
+
+
+
+CHAPTER I.
+
+EARLY YEARS; 1738-1772.
+
+
+Of the great modern philosophers, that one of whom least is known, is
+WILLIAM HERSCHEL. We may appropriate the words which escaped him when
+the barren region of the sky near the body of _Scorpio_ was passing
+slowly through the field of his great reflector, during one of his
+sweeps, to express our own sense of absence of light and knowledge:
+_Hier ist wahrhaftig ein Loch im Himmel._
+
+HERSCHEL prepared, about the year 1818, a biographical memorandum, which
+his sister CAROLINA placed among his papers.
+
+This has never been made public. The only thoroughly authentic sources
+of information in possession of the world, are a letter written by
+HERSCHEL himself, in answer to a pressing request for a sketch of his
+life, and the _Memoir and Correspondence of CAROLINE HERSCHEL_ (London,
+1876), a precious memorial not only of his life, but of one which
+otherwise would have remained almost unknown, and one, too, which the
+world could ill afford to lose. The latter, which has been ably edited
+by Mrs. MARY CORNWALLIS HERSCHEL,[1] is the only source of knowledge in
+regard to the early years of the great astronomer, and together with the
+all too scanty materials to be gained from a diligent search through the
+biography of the time, affords the data for those personal details of
+his life, habits, and character, which seem to complete the distinct,
+though partial conception of him which the student of his philosophical
+writings acquires.
+
+The letter referred to was published in the Goettingen Magazine of
+Science and Literature, III., 4, shortly after the name of HERSCHEL had
+become familiar to every ear through his discovery of _Uranus_, but
+while the circumstances of the discovery, and the condition of the
+amateur who made it, were still entirely unknown.
+
+The editor (LICHTENBERG) says:
+
+    "Herr HERSCHEL was good enough to send me, some time since, through
+    Herr MAGELLAN, copies of his Dissertations on Double Stars, on the
+    Parallax of the Fixed Stars, and on a new Micrometer. In the letter
+    which conveyed to him my thanks for his gift, I requested him to
+    note down a few facts in regard to his life, for publication in this
+    magazine, since various accounts, more or less incorrect, had
+    appeared in several journals. In answer, I received a very obliging
+    letter from him and what follows is that portion of it relating to
+    my request, which was sent me with full permission to make it
+    public."
+
+
+                                                "DATCHET, NEAR WINDSOR,
+                                                _Nov. 15, 1783._
+
+    "I was born in Hanover, November, 1738. My father, who was a
+    musician, destined me to the same profession, hence I was
+    instructed betimes in his art. That I might acquire a perfect
+    knowledge of the theory as well as of the practice of music, I was
+    set at an early age to study mathematics in all its
+    branches--algebra, conic sections, infinitesimal analysis, and the
+    rest.
+
+    "The insatiable desire for knowledge thus awakened resulted next in
+    a course of languages; I learned French, English, and Latin, and
+    steadfastly resolved henceforth to devote myself wholly to those
+    sciences from the pursuit of which I alone looked for all my future
+    happiness and enjoyment. I have never been either necessitated or
+    disposed to alter this resolve. My father, whose means were limited,
+    and who consequently could not be as liberal to his children as he
+    would have desired, was compelled to dispose of them in one way or
+    another at an early age; consequently in my fifteenth year I
+    enlisted in military service, only remaining in the army, however,
+    until I reached my nineteenth year, when I resigned and went over to
+    England.
+
+    "My familiarity with the organ, which I had carefully mastered
+    previously, soon procured for me the position of organist in
+    Yorkshire, which I finally exchanged for a similar situation at Bath
+    in 1766, and while here the peculiar circumstances of my post, as
+    agreeable as it was lucrative, made it possible for me to occupy
+    myself once more with my studies, especially with mathematics. When,
+    in the course of time, I took up astronomy, I determined to accept
+    nothing on faith, but to see with my own eyes everything which
+    others had seen before me. Having already some knowledge of the
+    science of optics, I resolved to manufacture my own telescopes, and
+    after many continuous, determined trials, I finally succeeded in
+    completing a so-called Newtonian instrument, seven feet in length.
+    From this I advanced to one of ten feet, and at last to one of
+    twenty, for I had fully made up my mind to carry on the improvement
+    of my telescopes as far as it could possibly be done. When I had
+    carefully and thoroughly perfected the great instrument in all its
+    parts, I made systematic use of it in my observations of the
+    heavens, first forming a determination never to pass by any, the
+    smallest, portion of them without due investigation. This habit,
+    persisted in, led to the discovery of the new planet (_Georgium
+    Sidus_). This was by no means the result of chance, but a simple
+    consequence of the position of the planet on that particular
+    evening, since it occupied precisely that spot in the heavens which
+    came in the order of the minute observations that I had previously
+    mapped out for myself. Had I not seen it just when I did, I must
+    inevitably have come upon it soon after, since my telescope was so
+    perfect that I was able to distinguish it from a fixed star in the
+    first minute of observation.
+
+    "Now to bring this sketch to a close. As the king had expressed a
+    desire to see my telescope, I took it by his command to Greenwich,
+    where it was compared with the instruments of my excellent friend,
+    Dr. MASKELYNE, not only by himself, but by other experts, who
+    pronounced it as their opinion that my instrument was superior to
+    all the rest. Thereupon the king ordered that the instrument be
+    brought to Windsor, and since it there met with marked approval, his
+    majesty graciously awarded me a yearly pension, that I might be
+    enabled to relinquish my profession of music, and devote my whole
+    time to astronomy and the improvement of the telescope. Gratitude,
+    as well as other considerations specified by me in a paper presented
+    to the Royal Society, of which I am a member, has induced me to call
+    the new planet _Georgium Sidus_.
+
+        "'Georgium Sidus.--jam nunc assuesce vocari.'--(_Virgil._)
+
+    And I hope it will retain the name."
+
+We know but little of the family of HERSCHEL. The name is undoubtedly
+Jewish, and is found in Poland, Germany, and England. We learn that the
+ancestors of the present branch left Moravia about the beginning of the
+XVIIth century, on account of their change of religion to Protestantism.
+They became possessors of land in Saxony. HANS HERSCHEL, the
+great-grandfather of WILLIAM, was a brewer in Pirna (a small town near
+Dresden). Of the two sons of HANS, one, ABRAHAM (born in 1651, died
+1718), was employed in the royal gardens at Dresden, and seems to have
+been a man of taste and skill in his calling. Of his eldest son,
+EUSEBIUS, there appears to be little trace in the records of the family.
+The second son, BENJAMIN, died in infancy; the third, ISAAC, was born in
+1707 (Jan. 14), and was thus an orphan at eleven years of age. ISAAC was
+the father of the great astronomer.
+
+He appears to have early had a passionate fondness for music, and this,
+added to a distaste for his father's calling, determined his career. He
+was taught music by an oboe-player in the royal band, and he also
+learned the violin. At the age of twenty-one he studied music for a year
+under the Cappelmeister PABRICH, at Potsdam, and in August, 1731, he
+became oboist in the band of the Guards, at Hanover. In August, 1732, he
+married ANNA ILSE MORITZEN. She appears to have been a careful and busy
+wife and mother, possessed of no special faculties which would lead us
+to attribute to her care any great part of the abilities of her son.
+She could not herself write the letters which she sent to her husband
+during his absences with his regiment. It was her firm belief that the
+separations and some of the sorrows of the family came from too much
+learning; and while she could not hinder the education of the sons of
+the family, she prevented their sisters from learning French and
+dancing. It is but just to say that the useful accomplishments of
+cooking, sewing, and the care of a household, were thoroughly taught by
+her to her two daughters. The father, ISAAC, appears to have been of a
+different mould, and to him, no doubt, the chief intellectual
+characteristics of the family are due. His position obliged him to be
+often absent from Hanover, with his regiment, but his hand appears to
+have been always present, smoothing over difficulties, and encouraging
+his sons to such learning and improvement as was to be had.
+
+His health was seriously injured by the exposures of the campaigns,
+and he was left, after the Seven Years' War, with a broken constitution.
+
+After his final return home, in 1760, his daughter gives this record of
+him--
+
+    "Copying music employed every vacant moment, even sometimes
+    throughout half the night. . . . With my brother [DIETRICH]--now a
+    little engaging creature of between four and five years old--he was
+    very much pleased, and [on the first evening of his arrival at home]
+    before he went to rest, the Adempken (a little violin) was taken
+    from the shelf and newly strung, and the daily lessons immediately
+    commenced. . . . I do not recollect that he ever desired any other
+    society than what he had opportunities of enjoying in many of the
+    parties where he was introduced by his profession, though far from
+    being of a morose disposition; he would frequently encourage my
+    mother in keeping up a social intercourse among a few acquaintances,
+    whilst his afternoon hours generally were taken up in giving lessons
+    to some scholars at home, who gladly saved him the troublesome
+    exertion of walking. . . . He also found great pleasure in seeing
+    DIETRICH'S improvement, who, young as he was, and of the most lively
+    temper imaginable, was always ready to receive his lessons, leaving
+    his little companions with the greatest cheerfulness to go to his
+    father, who was so pleased with his performances that he made him
+    play a solo on the Adempken in RAKE'S concert, being placed on a
+    table before a crowded company, for which he was very much applauded
+    and caressed, particularly by an English lady, who put a gold coin
+    in his little pocket.
+
+    "It was not long before my father had as many scholars as he could
+    find time to attend. And when they assembled at my father's to make
+    little concerts, I was frequently called to join the second violin
+    in an overture, for my father found pleasure in giving me sometimes
+    a lesson before the instruments were laid by, after practising with
+    DIETRICH, for I never was missing at those hours, sitting in a
+    corner with my knitting and listening all the while."
+
+Here, as in all her writing, CAROLINA is simple, true, direct to
+awkwardness, and unconsciously pathetic even in joy.
+
+The family of ISAAC and ANNA HERSCHEL consisted of ten children. Six of
+these lived to adult age. They were:
+
+    1. SOPHIA ELIZABETH; born 1733, married GRIESBACH, a musician in the
+       Guard, by whom she had children. Five of her sons were afterwards
+       musicians at the court, in England, where they obtained places
+       through the influence of WILLIAM.
+
+    2. HENRY ANTON JACOB; born 1734, November 20.
+
+    4. FREDERIC WILLIAM (the astronomer) born 1738, November 15.
+
+    6. JOHN ALEXANDER; born 1745, November 13.
+
+    8. CAROLINA LUCRETIA; born 1750, March 16.
+
+    10. DIETRICH; born 1755, September 13.
+
+Of this family group, the important figures to us are WILLIAM,
+ALEXANDER, and CAROLINA.
+
+JACOB was organist at the Garrison Church of Hanover in 1753, a member
+of the Guards' band in 1755, and first violin in the Hanover Court
+Orchestra in 1759. Afterwards he joined his brother WILLIAM in Bath, but
+again returned to Hanover. In 1771 he published in Amsterdam his Opus
+I., a set of six quartettes, and later, in London, he published two
+symphonies and six trios. He appears to have been a clever musician, and
+his letters to his younger brother WILLIAM are full of discussion on
+points of musical composition, etc. He died in 1792.
+
+DIETRICH, the youngest brother, shared in the musical abilities of his
+family, and when only fifteen years old was so far advanced as to be
+able to supply his brother JACOB'S place in the Court Orchestra, and to
+give his lessons to private pupils. There is no one of the family,
+except the eldest daughter, whom we do not know to have possessed marked
+ability in music, and this taste descended truly for four generations.
+In the letters of Chevalier BUNSEN,[2] he describes meeting, in 1847,
+the eldest granddaughter of WILLIAM HERSCHEL, who, he says, "is a
+musical genius."
+
+Three members of the family, WILLIAM, ALEXANDER, and CAROLINA, formed a
+group which was inseparable for many years, and while the progress of
+the lives of ALEXANDER and CAROLINA was determined by the energy and
+efforts of WILLIAM, these two lent him an aid without which his career
+would have been strangely different. It is necessary to understand a
+little better the early life of all three.
+
+The sons of the HERSCHEL family all attended the garrison school in
+Hanover until they were about fourteen years old. They were taught the
+ordinary rudiments of knowledge--to read, to write, to cipher--and a
+knowledge of French and English was added. WILLIAM especially
+distinguished himself in his studies, learning French very rapidly, and
+studying Latin and arithmetic with his master out of hours. The
+household life seems to have been active, harmonious, and intelligent,
+especially during the presence of the father, who took a great delight
+in the rapid progress of all his sons in music, and who encouraged them
+with his companionship in their studies and in their reading on all
+intellectual subjects.
+
+From the _Memoir_ of CAROLINA, on which we must depend for our
+knowledge of this early life, we take the following paragraph:
+
+    "My brothers were often introduced as solo performers and assistants
+    in the orchestra of the court, and I remember that I was frequently
+    prevented from going to sleep by the lively criticism on music on
+    coming from a concert, or by conversations on philosophical subjects,
+    which lasted frequently till morning, in which my father was a
+    lively partaker and assistant of my brother WILLIAM, by contriving
+    self-made instruments. . . . Often I would keep myself awake that
+    I might listen to their animating remarks, for it made _me so happy_
+    to see _them so happy_. But generally their conversation would
+    branch out on philosophical subjects, when my brother WILLIAM and my
+    father often argued with such warmth that my mother's interference
+    became necessary, when the names LEIBNITZ, NEWTON, and EULER
+    sounded rather too loud for the repose of her little ones, who
+    ought to be in school by seven in the morning. But it seems that
+    on the brothers retiring to their own room, where they shared
+    the same bed, my brother WILLIAM had still a great deal to say; and
+    frequently it happened that when he stopped for an assent or reply,
+    he found his hearer was gone to sleep, and I suppose it was not till
+    then that he bethought himself to do the same.
+
+    "The recollection of these happy scenes confirms me in the belief,
+    that had my brother WILLIAM not then been interrupted in his
+    philosophical pursuits, we should have had much earlier proofs of
+    his inventive genius. My father was a great admirer of astronomy,
+    and had some knowledge of that science; for I remember his taking
+    me, on a clear frosty night, into the street, to make me acquainted
+    with several of the most beautiful constellations, after we had been
+    gazing at a comet which was then visible. And I well remember with
+    what delight he used to assist my brother WILLIAM in his various
+    contrivances in the pursuit of his philosophical studies, among
+    which was a neatly turned 4-inch globe, upon which the equator and
+    ecliptic were engraved by my brother."
+
+The mechanical genius was not confined to WILLIAM, for we read that
+ALEXANDER used often to "sit by us and amuse us and himself by making
+all sorts of things out of pasteboard, or contriving how to make a
+twelve-hour cuckoo clock go a week." This ability of ALEXANDER'S was
+turned later to the best account when he became his brother WILLIAM'S
+right hand in the manufacture of reflectors, eye-pieces, and stands in
+England. His abilities were great, and a purpose which might otherwise
+have been lacking was supplied through the younger brother's ardor in
+all that he undertook.
+
+His musical talent was remarkable; he played "divinely" on the
+violoncello. He returned to Hanover in 1816, where he lived in
+comfortable independence, through the never-failing generosity of his
+brother, until his death in 1821. A notice of him in a Bristol paper
+says: "Died, March 15, 1821, at Hanover, ALEXANDER HERSCHEL, Esqr., well
+known to the public of Bath and Bristol as a performer and elegant
+musician; and who for forty-seven years was the admiration of the
+frequenters of concerts and theatres of both those cities as principal
+violoncello. To the extraordinary merits of Mr. HERSCHEL was united
+considerable acquirement in the superior branches of mechanics and
+philosophy, and his affinity to his brother, Sir WILLIAM HERSCHEL, was
+not less in science than in blood."
+
+We shall learn more of the sister, CAROLINA, as time goes on. Now in
+these early years she was a silent and persistent child, growing up with
+a feeling that she was uncared for and neglected, and lavishing all her
+childish affection, as she did all that of her womanly life, on her
+brother WILLIAM. Throughout her long life, "my brother" was WILLIAM,
+"my nephew" _his_ son.
+
+The brothers JACOB and WILLIAM were, with their father, members of the
+band of the Guards in 1755, when the regiment was ordered to England,
+and they were absent from Hanover a year.
+
+WILLIAM (then seventeen years old) went as oboist, and out of his
+scanty pay brought back to Hanover, in 1756, only one memento of his
+stay--a copy of LOCKE _On the Human Understanding_.
+
+He appears to have served with the Guard during part of the campaign of
+1757. His health was then delicate, and his parents "determined to
+remove him from the service--a step attended by no small
+difficulties."[3]
+
+This "removal" was hurriedly and safely effected, so hurriedly that the
+copy of LOCKE was not put in the parcels sent after him to Hamburg by
+his mother; "she, dear woman, knew no other wants than good linen and
+clothing."
+
+Thus, at last, the young WILLIAM HERSCHEL, the son of an oboe-player in
+the King's Guard, is launched in life for himself, in the year 1757, at
+the age of nineteen.
+
+All his equipment is the "good linen and clothing," a knowledge of
+French, Latin, and English, some skill in playing the violin, the organ,
+and the oboe, and an "uncommon precipitancy" in doing what there is to
+be done.
+
+A slender outfit truly; but we are not to overlook what he said of
+himself on another occasion. "I have, nevertheless, several resources in
+view, and do not despair of succeeding pretty well in the end."
+
+From 1757 to 1760--three years--we know nothing of his life. We can
+imagine what it was. His previous visit to England had given him a good
+knowledge of the language, and perhaps a few uninfluential
+acquaintances. On his return he would naturally seek these out, and, by
+means of his music, he could gain a livelihood. We first hear of him as
+charged with the organization of the music of a corps of the militia of
+Durham, under the auspices of the EARL OF DARLINGTON. "La maniere dont
+il remplit cette mission, le fit connaitre avantageusement."[4] The
+nature of the service of these militia corps, which were then forming
+all over England, is well described in the Autobiography of GIBBON.
+Every county-gentleman felt constrained to serve his country,
+and the regimental mess-rooms were filled with men of rank and fashion.
+
+In 1760 we hear of him again. He has attracted the notice of those about
+him.
+
+    "About the year 1760, as MILLER[5] was dining at Pontefract with
+    the officers of the Durham militia, one of them, knowing his love of
+    music, told him they had a young German in their band as a performer
+    on the hautboy, who had only been a few months in England, and yet
+    spoke English almost as well as a native, and who was also an
+    excellent performer on the violin; the officer added that if MILLER
+    would come into another room, this German should entertain him with
+    a solo. The invitation was gladly accepted, and MILLER heard a solo
+    of GIARDINI'S executed in a manner that surprised him. He afterwards
+    took an opportunity of having some private conversation with the
+    young musician, and asked him whether he had engaged himself for any
+    long period to the Durham militia. The answer was, 'Only from month
+    to month.' 'Leave them, then,' said the organist, 'and come and live
+    with me. I am a single man, and think we shall be happy together;
+    and, doubtless, your merit will soon entitle you to a more eligible
+    situation.' The offer was accepted as frankly as it was made, and
+    the reader may imagine with what satisfaction Dr. MILLER
+    must have remembered this act of generous feeling when he hears
+    that this young German was HERSCHEL, the Astronomer. 'My humble
+    mansion,' says MILLER, 'consisted, at that time, but of two rooms.
+    However, poor as I was, my cottage contained a library of
+    well-chosen books; and it must appear singular that a foreigner who
+    had been so short a time in England should understand even the
+    peculiarities of the language so well as to fix upon SWIFT for his
+    favorite author.'
+
+    "He took an early opportunity of introducing his new friend at
+    Mr. CROPLEY'S concerts; the first violin was resigned to him; 'and
+    never,' says the organist, 'had I heard the concertos of CORELLI,
+    GEMINIANI, and AVISON, or the overtures of HANDEL performed more
+    chastely, or more according to the original intention of the
+    composers, than by Mr. HERSCHEL. I soon lost my companion; his fame
+    was presently spread abroad; he had the offer of pupils, and was
+    solicited to lead the public concerts both at Wakefield and Halifax.
+    A new organ for the parish church of Halifax was built about this
+    time, and HERSCHEL was one of the seven candidates for the
+    organist's place. They drew lots how they were to perform in
+    succession. HERSCHEL drew the third, the second fell to Dr.
+    WAINWRIGHT of Manchester, whose finger was so rapid that old
+    SNETZLER, the organ-builder, ran about the church exclaiming:
+    '_Te tevel! te tevel! he run over te keys like one cat; he will
+    not give my piphes room for to shpeak._' 'During Mr. WAINWRIGHT'S
+    performance,' says MILLER, 'I was standing in the middle aisle with
+    HERSCHEL. 'What chance have you,' said I, 'to follow this man?' He
+    replied, 'I don't know; I am sure fingers will not do.' On which he
+    ascended the organ loft, and produced from the organ so uncommon a
+    fulness, such a volume of slow, solemn harmony, that I could by no
+    means account for the effect. After this short _ex tempore_
+    effusion, he finished with the Old Hundredth psalm-tune, which he
+    played better than his opponent.
+
+    "'_Ay, ay_,' cried old SNETZLER, '_tish is very goot, very goot
+    indeet; I vil luf tish man, for he gives my piphes room for to
+    shpeak._' Having afterwards asked Mr. HERSCHEL by what means, in the
+    beginning of his performance, he produced so uncommon an effect, he
+    replied, 'I told you fingers would not do!' and producing two pieces
+    of lead from his waistcoat pocket, 'one of these,' said he,
+    'I placed on the lowest key of the organ, and the other upon the
+    octave above; thus by accommodating the harmony, I produced the
+    effect of four hands, instead of two.'"[6]
+
+The dates in this extract are not so well defined as might be wished.
+HERSCHEL had certainly been more than a few months in England at the
+time of his meeting with Dr. MILLER, which was probably about 1760. The
+appointment as organist at Halifax was in 1765, and the pupils and
+public concerts must have filled up the intervening five years. During a
+part of this time he lived in Leeds, with the family of Mr. BULMAN, whom
+he afterwards provided with a place as clerk to the Octagon Chapel, in
+his usual generous manner.
+
+All during his life he was placing some of the less fortunate and
+energetic members of his family.
+
+We cannot be too grateful to Dr. MILLER, who, seeing his opportunity,
+used it. Their frank friendship does honor to both. HERSCHEL'S
+organ-playing, which no doubt had been begun when his brother was the
+organist of the garrison chapel at Hanover, must have been perfected at
+this time, and it was through his organ-playing that he was able to
+leave the needy life in Yorkshire.
+
+He was sure to have emerged sooner or later, but every year spared to
+him as a struggling musician was a year saved to Astronomy.
+
+During all this period, a constant correspondence was maintained
+between the family at Hanover and the absent son.
+
+Many of WILLIAM'S letters were written in English, and addressed to his
+brother JACOB, and treated of such subjects as the Theory of Music, in
+which he was already far advanced.
+
+His little sister was still faithful to the memory of her _dearest_
+brother, and his father, whose health was steadily declining, became
+painfully eager for his return. In 1764 (April 2), he returned to
+Hanover on a very brief visit. He was attached to England, he was
+prospering there, and he had no inclination towards returning to a life
+in Hanover. His sister says:
+
+    "Of the joys and pleasures which all felt at this long-wished-for
+    meeting with my--let me say my _dearest_--brother, but a small
+    portion could fall to my share; for with my constant attendance at
+    church and school, besides the time I was employed in doing the
+    drudgery of the scullery, it was but seldom I could make one in the
+    group when the family were assembled together.
+
+    "In the first week, some of the orchestra were invited to a concert,
+    at which some of my brother WILLIAM'S compositions, overtures, etc.,
+    and some of my eldest brother JACOB'S were performed, to the great
+    delight of my dear father, who hoped and expected that they would
+    be turned to some profit by publishing them, but there was no
+    printer who bid high enough.
+
+    "Sunday, the 8th, was the--to me--eventful day of my confirmation,
+    and I left home not a little proud and encouraged by my dear brother
+    WILLIAM'S approbation of my appearance in my new gown."
+
+The engagement of HERSCHEL at Halifax did not long continue. In 1766 he
+obtained an advantageous engagement as oboist at Bath, and soon after
+the position of organist at the Octagon Chapel was offered to him and
+accepted. This was a great and important change.
+
+Bath was then, as now, one of the most beautiful cities in England, and
+the resort of the fashion and rank of the kingdom, who came to take the
+waters. It is beautifully situated on both sides of the Avon, and has
+many fine walks and public buildings. The aspect of the city is markedly
+cheerful and brilliant, owing to the nature of the white stone of which
+the principal houses are built, and to the exquisite amphitheatre of
+hills in which they lie.
+
+The society was then gay and polite, and HERSCHEL was at once thrown
+into a far more intelligent atmosphere than that he had just left in
+Yorkshire. It was easy to get new books, to see new faces, to hear new
+things. The Assembly Rooms (built in 1771) were noted for their size and
+elegance; the theatre was the best out of London.
+
+His position as organist of the fashionable chapel placed him in the
+current. His charming and engaging manners made him friends. His talents
+brought him admirers and pupils, and pupils brought him money.[7]
+
+He began in 1766 a life of unceasing activity, which continued. In 1768
+he published in London a symphony (in C) for two violins, viola, bass,
+two oboes, and two horns, and in the same year two military concertos
+for two oboes, two horns, two trumpets, and two bassoons.[8] He wrote
+pieces for the harp, glees, "catches," and other songs for the
+voice. One of these, the _Echo Catch_, was published and had even
+considerable vogue.
+
+    A competent musical critic writes to me of this work: "The
+    counterpoint is clear and flowing, and is managed with considerable
+    taste and effect. It would be difficult to explain the great
+    cleverness shown in the construction of the _Catch_ without diagrams
+    to illustrate the movements of the parts. It is certainly an
+    ingenious bit of musical writing."
+
+When he left Bath (in 1782), many of these musical writings were lost,
+in his great haste to take up his new profession. One, specially, his
+sister remembers to have written out for the printer, "but he could not
+find a moment to send it off, nor answer the printer's letters." This
+was a four-part song, "In thee I bear so dear a part." He wrote very
+many anthems, chants, and psalm-tunes for the excellent cathedral choir
+of the Octagon Chapel. Unfortunately, most of this music is now not to
+be found.
+
+A notice of HERSCHEL'S life which appeared in the _European Magazine_
+for 1785, January, gives a very lively picture of his life at this
+time, and it is especially valuable as showing how he appeared to his
+cotemporaries.
+
+    "Although Mr. HERSCHEL loved music to an excess, and made a
+    considerable progress in it, he yet determined with a sort of
+    enthusiasm to devote every moment he could spare from business to
+    the pursuit of knowledge, which he regarded as the sovereign good,
+    and in which he resolved to place all his views of future happiness
+    in life.". . .
+
+    "His situation at the Octagon Chapel proved a very profitable one,
+    as he soon fell into all the public business of the concerts, the
+    Rooms, the Theatre, and the oratorios, besides many scholars and
+    private concerts. This great run of business, instead of lessening
+    his propensity to study, increased it, so that many times, after a
+    fatiguing day of fourteen or sixteen hours spent in his vocation, he
+    would retire at night with the greatest avidity to _unbend the
+    mind_, if it may be so called, with a few propositions in
+    MACLAURIN'S _Fluxions_, or other books of that sort."
+
+It was in these years that he mastered Italian and made some progress
+in Greek.
+
+    "We may hazard a natural conjecture respecting the course of
+    HERSCHEL'S early studies. Music conducted him to mathematics, or,
+    in other words, impelled him to study SMITH'S _Harmonics_. Now this
+    ROBERT SMITH was the author of _A Complete System of Optics_,
+    a masterly work, which, notwithstanding the rapid growth of that
+    branch of the science, is not yet wholly superseded. It seems to us
+    not unlikely that HERSCHEL, studying the _Harmonics_, conceived a
+    reverence for the author, who was at that time still living, so that
+    from the _Philosophy of Music_ he passed to the _Optics_, a work on
+    which SMITH'S great reputation chiefly rested; and thus undesignedly
+    prepared himself for the career on which he was shortly about to
+    enter with so much glory."[9]
+
+There is no doubt that this conjecture is a true one. The _Optics_ of
+Dr. SMITH is one of the very few books quoted by HERSCHEL throughout his
+writings, and there is every evidence of his complete familiarity with
+its conclusions and methods; and this familiarity is of the kind which a
+student acquires with his early text-books. One other work he quotes in
+the same way, LALANDE'S _Astronomy_, and this too must have been deeply
+studied.
+
+During the years 1765-1772, while HERSCHEL was following his profession
+and his studies at Bath, the family life at Hanover went on in much the
+same way.
+
+In 1765 his father ISAAC had a stroke of paralysis, which ended his
+violin-playing forever, and forced him to depend entirely upon pupils
+and copying of music for a livelihood. He died on March 22, 1767,
+leaving behind him a good name, and living in the affectionate
+remembrance of his children and of all who knew him.
+
+CAROLINA had now lost her best friend, and transferred to her brother
+WILLIAM the affection she had before divided between him and her father.
+
+    "My father wished to give me something like a polished education,
+    but my mother was particularly determined that it should be a rough,
+    but at the same time a useful one; and nothing farther she thought
+    was necessary but to send me two or three months to a sempstress to
+    be taught to make household linen. . . . My mother would not consent
+    to my being taught French, and my brother Dietrich was even denied a
+    dancing-master, because she would not permit my learning along with
+    him, though the entrance had been paid for us both; so all my father
+    could do for me was to indulge me (and please himself) sometimes
+    with a short lesson on the violin, when my mother was either in
+    good humor or out of the way. Though I have often felt myself
+    exceedingly at a loss for the want of those few accomplishments of
+    which I was thus, by an erroneous though well-meant opinion of my
+    mother, deprived, I could not help thinking but that she had cause
+    for wishing me not to know more than was necessary for being useful
+    in the family; for it was her certain belief that my brother WILLIAM
+    would have returned to his country, and my eldest brother not have
+    looked so high, if they had had a little less learning.
+
+          *       *       *       *       *
+
+    But sometimes I found it scarcely possible to get through with the
+    work required, and felt very unhappy that no time at all was left
+    for improving myself in music or fancy work, in which I had an
+    opportunity of receiving some instruction from an ingenious young
+    woman whose parents lived in the same house with us. But the time
+    wanted for spending a few hours together could only be obtained by
+    our meeting at daybreak, because by the time of the family's rising
+    at seven, I was obliged to be at my daily business. Though I had
+    neither time nor means for producing anything immediately either for
+    show or use, I was content with keeping samples of all possible
+    patterns in needlework, beads, bugles, horse-hair, etc., for I could
+    not help feeling troubled sometimes about my future destiny; yet I
+    could not bear the idea of being turned into an Abigail or
+    housemaid, and thought that with the above and such like
+    acquirements, with a little notion of music, I might obtain a place
+    as governess in some family where the want of a knowledge of French
+    would be no objection."
+
+A change was soon to come in her life too; her brother WILLIAM wrote
+to propose that she should join him at Bath--
+
+    . . . "to make the trial, if, by his instruction, I might not become
+    a useful singer for his winter concerts and oratorios; he advised my
+    brother JACOB to give me some lessons by way of beginning; but that
+    if, after a trial of two years, we should not find it answer our
+    expectation, he would bring me back again. This at first seemed to
+    be agreeable to all parties, but by the time I had set my heart upon
+    this change in my situation, JACOB began to turn the whole scheme
+    into ridicule, and, of course, he never heard the sound of my voice
+    except in speaking, and yet I was left in the harassing uncertainty
+    whether I was to go or not. I resolved at last to prepare, as far as
+    lay in my power, for both cases, by taking, in the first place,
+    every opportunity, when all were from home, to imitate, with a gag
+    between my teeth, the solo parts of concertos, _shake and all_, such
+    as I had heard them play on the violin; in consequence I had gained
+    a tolerable execution before I knew how to sing. I next began to
+    knit ruffles, which were intended for my brother WILLIAM, in case I
+    remained at home--else they were to be JACOB'S. For my mother and
+    brother D. I knitted as many cotton stockings as would last two
+    years at least."
+
+In August, 1772, her brother arrived at Hanover, to take her back to
+England with him. The journey to London was made between August 16th and
+26th, and soon after they went together to HERSCHEL'S house, No. 7 New
+King's Street, Bath.
+
+FOOTNOTES:
+
+[1] Wife of Major JOHN HERSCHEL, of the Royal Engineers,
+grandson of Sir WILLIAM.
+
+[2] Page 127.
+
+[3] _Memoir_ of CAROLINA HERSCHEL, p. 10. Sir GEORGE AIRY,
+Astronomer Royal, relates in the _Academy_ that this "removal" was a
+desertion, as he was told by the Duke of Sussex that on the first visit
+of HERSCHEL to the king, after the discovery of the _Georgium Sidus_,
+the pardon of HERSCHEL was handed to him by the king himself, written
+out in due form.
+
+[4] FETIS; _Biographie universelle des musiciens_, tome V.
+(1839) p. 141.
+
+[5] Dr. MILLER, a noted organist, and afterwards historian of
+Doncaster.
+
+[6] _The Doctor_; by ROBERT SOUTHEY, edition of 1848, p.
+140.
+
+[7] He frequently gave thirty-five and thirty-eight lessons a
+week to pupils at this time.
+
+[8] According to FETIS. A search for these in London has led
+me to the belief that FETIS, who is usually very accurate, is here
+mistaken, and that these writings are by JACOB HERSCHEL.
+
+[9] _Foreign Quarterly Review_, volume 31.
+
+
+
+
+                           CHAPTER II.
+
+                    LIFE IN BATH; 1772-1782.
+
+
+It was to a busy life in Bath that HERSCHEL took his sister CAROLINA,
+then twenty-two years old. She was a perfectly untried girl, of very
+small accomplishments and outwardly with but little to attract. The
+basis of her character was the possibility of an unchanging devotion to
+one object; for the best years of her life this object was the happiness
+and success of her brother WILLIAM, whom she profoundly loved. Her love
+was headstrong and full of a kind of obstinate pride, which refused to
+see anything but the view she had adopted. As long as her life continued
+to be with her dearest brother, all was well with her. She had a noble
+aim, and her heart was more than full. Later on, this very singleness of
+character brought her other years of wretchedness. It is necessary to
+understand the almost spaniel-like allegiance she gave, in order to
+comprehend the value which her services were to HERSCHEL. She supplied
+him with an aid which was utterly loyal, entire, and devoted. Her
+obedience was unquestioning, her reverence amounted almost to adoration.
+In their relation, he gave everything in the way of incentive and
+initiative, and she returned her entire effort loyally.
+
+At first her business was to gain a knowledge of the language, and to
+perfect herself in singing, so that she might become a soloist in the
+concerts and oratorios which he was constantly giving.
+
+In the beginning it was not easy.
+
+    . . . "As the season for the arrival of visitors to the baths does
+    not begin till October, my brother had leisure to try my capacity for
+    becoming a useful singer for his concerts and oratorios, and being
+    very well satisfied with my voice, I had two or three lessons every
+    day, and the hours which were not spent at the harpsichord, were
+    employed in putting me in the way of managing the family. . . .
+    On the second morning, on meeting my brother at breakfast, he began
+    immediately to give me a lesson in English and arithmetic, and
+    showed me the way of booking and keeping accounts of cash received
+    and laid out. . . . By way of relaxation we talked of astronomy and
+    the bright constellations with which I had made acquaintance during
+    the fine nights we spent on the postwagen travelling through Holland.
+
+    "My brother ALEXANDER, who had been some time in England, boarded
+    and lodged with his elder brother, and, with myself, occupied the
+    attic. The first floor, which was furnished in the newest and most
+    handsome style, my brother kept for himself. The front room,
+    containing the harpsichord, was always in order to receive his
+    musical friends and scholars at little private concerts or
+    rehearsals. . . . Sundays I received a sum for the weekly expenses,
+    of which my housekeeping book (written in English) showed the amount
+    laid out, and my purse the remaining cash. One of the principal
+    things required was to market, and about six weeks after coming to
+    England I was sent alone among fishwomen, butchers, basket-women,
+    etc., and I brought home whatever in my fright I could pick up. . . .
+    My brother ALEX., who was now returned from his summer engagement,
+    used to watch me at a distance, unknown to me, till he saw me safe
+    on my way home. But all attempts to introduce any order in our
+    little household proved vain, owing to the servant my brother then
+    had. And what still further increased my difficulty was, that my
+    brother's time was entirely taken up with business, so that I only
+    saw him at meals. Breakfast was at seven o'clock or before--much too
+    early for me, who would rather have remained up all night than be
+    obliged to rise at so early an hour. . . .
+
+    "The three winter months passed on very heavily. I had to struggle
+    against _heimwehe_ (home sickness) and low spirits, and to answer my
+    sister's melancholy letters on the death of her husband, by which
+    she became a widow with six children. I knew too little English to
+    derive any consolation from the society of those who were about me,
+    so that, dinner-time excepted, I was entirely left to myself."
+
+So the winter passed.
+
+    "The time when I could hope to receive a little more of my brother's
+    instruction and attention was now drawing near; for after Easter,
+    Bath becomes very empty, only a few of his scholars, whose families
+    were resident in the neighborhood, remaining. But I was greatly
+    disappointed; for, in consequence of the harassing and fatiguing
+    life he had led during the winter months, he used to retire to bed
+    with a basin of milk or glass of water, and SMITH'S _Harmonics_ and
+    _Optics_, FERGUSON'S _Astronomy_, etc., and so went to sleep buried
+    under his favorite authors; and his first thoughts on rising were
+    how to obtain instruments for viewing those objects himself of which
+    he had been reading. There being in one of the shops a
+    two-and-a-half-foot Gregorian telescope to be let, it was for some
+    time taken in requisition, and served not only for viewing the
+    heavens, but for making experiments on its construction. . . . It soon
+    appeared that my brother was not contented with knowing what former
+    observers had seen, for he began to contrive a telescope eighteen or
+    twenty feet long (I believe after HUYGHENS' description). . . . I was
+    much hindered in my musical practice by my help being continually
+    wanted in the execution of the various contrivances, and I had to
+    amuse myself with making the tube of pasteboard for the glasses,
+    which were to arrive from London, for at that time no optician had
+    settled at Bath. But when all was finished, no one besides my
+    brother could get a glimpse of Jupiter or Saturn, for the great
+    length of the tube would not allow it to be kept in a straight line.
+    This difficulty, however, was soon removed by substituting tin
+    tubes. . . . My brother wrote to inquire the price of a reflecting
+    mirror for (I believe) a five or six foot telescope. The answer was,
+    there were none of so large a size, but a person offered to make one
+    at a price much above what my brother thought proper to give. . . .
+    About this time he bought of a Quaker, resident at Bath, who had
+    formerly made attempts at polishing mirrors, all his rubbish of
+    patterns, tools, hones, polishers, unfinished mirrors, etc., but all
+    for small Gregorians, and none above two or three inches diameter.
+
+    "But nothing serious could be attempted, for want of time, till the
+    beginning of June, when some of my brother's scholars were leaving
+    Bath; and then, to my sorrow, I saw almost every room turned into a
+    workshop. A cabinet-maker making a tube and stands of all
+    descriptions in a handsomely furnished drawing-room; ALEX. putting
+    up a huge turning machine (which he had brought in the autumn from
+    Bristol, where he used to spend the summer) in a bedroom, for
+    turning patterns, grinding glasses, and turning eye-pieces, etc. At
+    the same time music durst not lie entirely dormant during the
+    summer, and my brother had frequent rehearsals at home, where Miss
+    FARINELLI, an Italian singer, was met by several of the principal
+    performers he had engaged for the winter concerts."
+
+Finally, in 1774, he had made himself a Gregorian telescope,[10] and
+had begun to view the heavens. He was then thirty-six years old.
+
+The writer in the _European Magazine_ describes this period:
+
+    "All this time he continued his astronomical observations, and
+    nothing now seemed wanting to complete his felicity, but sufficient
+    leisure to enjoy his telescopes, to which he was so much attached,
+    that at the theatre he used frequently to run from the harpsichord
+    to look at the stars, during the time between the acts."
+
+In an extract from his _Journal No. 1_, now at the rooms of the Royal
+Society, may be seen a copy of his first observation of the Nebula of
+_Orion_, on March 4, 1774. This was made with his five-and-a-half-foot
+Gregorian reflector.
+
+It was at this time (1775), between the acts of the theatre, that he
+made his first review of the heavens, with a Newtonian telescope, of an
+aperture of four and a half inches and a magnifying power of 222 times.
+This telescope was one of the first made by himself. The review
+consisted of the examination of every star in the sky of the first,
+second, third, and fourth magnitudes, and of all planets visible. There
+are no records of these observations now extant, and they are noteworthy
+only as a preparation for more serious work.
+
+He was carrying out his resolve to see everything for himself. His
+assiduity may be judged of by the fact that between 1774 and 1781
+HERSCHEL had observed a single object--the Nebula of _Orion_--no less
+than fourteen times.
+
+The success of his first telescopes incited him to new efforts. His
+house became a complete _atelier_, where everything that could tend to
+excellence in this manufacture was tried and re-tried a hundred
+different ways. When a difficulty arose, experiments were begun which
+continued till it was conquered. When a success was gained, it was
+prosecuted to the utmost.
+
+In 1775 the first seven-foot reflector was made, in 1777 a ten-foot was
+finished, in 1778 a "very good" ten-foot took its place. It must not be
+thought that the telescopes mentioned were the only ones completed. On
+the contrary, they were but the best ones selected out of many.
+
+In 1774 a new house had been engaged, which had "more room for
+workshops," and whose roof gave space for observing. The grass-plat near
+it was soon utilized to hold the stand of a twenty-foot telescope, which
+he had even then projected. His projects were unending, no success was
+final; his mind was at the height of activity; his whole effort was
+thrown into every undertaking.
+
+The mirrors for all these telescopes were made by hand. Every portion
+of the grinding down to rough dimensions, the shaping to something near
+the correct form, the polishing till the accurately exact curves were
+obtained, all this must be done by hand. The machines for the purpose
+were not invented until 1788.[11]
+
+ALEXANDER and WILLIAM worked together at this, but most of the work was
+done by the latter. The sister's part was to attend in the workshop and
+lend a hand wherever and whenever it was needed.
+
+    . . . "My time was taken up with copying music and practising, besides
+    attendance on my brother when polishing, since by way of keeping him
+    alive I was constantly obliged to feed him by putting the victuals by
+    bits into his mouth. This was once the case when, in order to finish
+    a seven-foot mirror, he had not taken his hands from it for sixteen
+    hours together. In general he was never unemployed at meals, but was
+    always at those times contriving or making drawings of whatever
+    came in his mind. Generally I was obliged to read to him whilst
+    he was at the turning-lathe, or polishing mirrors, _Don Quixote_,
+    _Arabian Nights' Entertainment_, the novels of STERNE, FIELDING,
+    etc.; serving tea and supper without interrupting the work with
+    which he was engaged, . . . and sometimes lending a hand. I became,
+    in time, as useful a member of the workshop as a boy might be to
+    his master in the first year of his apprenticeship. . . . But as
+    I was to take a part the next year in the oratorios, I had, for a
+    whole twelvemonth, two lessons per week from Miss FLEMING, the
+    celebrated dancing-mistress, to drill me for a gentlewoman (God
+    knows how she succeeded). So we lived on without interruption.
+    My brother ALEX. was absent from Bath for some months every summer,
+    but when at home he took much pleasure in executing some turning or
+    clockmaker's work for his brother."
+
+News from Hanover put a sudden stop, for a time, to all these labors.
+The mother wrote, in the utmost distress, to say that DIETRICH had
+disappeared from his home, it was supposed with the intention of going
+to India "with a young idler not older than himself." His brother
+immediately left the lathe at which he was turning an eye-piece in
+cocoa-nut, and started for Holland, whence he proceeded to Hanover,
+failing to meet his brother, as he expected. Meanwhile the sister
+received a letter to say that DIETRICH was "laid up very ill" at an inn
+in Wapping. ALEXANDER posted to town, removed him to a lodging, and,
+after a fortnight's nursing, brought him to Bath, where, on his brother
+WILLIAM'S return, he found him being well cared for by his sister.
+
+About this time another change was made to the house 19 New King Street,
+which was the last move in Bath. It was here that the _Georgium Sidus_
+was discovered.
+
+The music still went on. The oratorios of the _Messiah_, _Judas
+Maccabeus_, and _Samson_ were to be performed under HERSCHEL'S
+direction, with an orchestra of nearly one hundred pieces. The scores
+and vocal parts of these CAROLINA copied with her own hands, and the
+_soprani_ were instructed by her, she being the leading soloist. Along
+with the music went the astronomy. Not only were new telescopes made,
+but they were made for immediate use.
+
+The variable star _Mira Ceti_ was observed, and a long series of lunar
+observations begun.
+
+    "In 1779, 1780, and 1781 I measured the heights of about one hundred
+    mountains of the moon, by three different methods.
+
+    "Some of these observations are given in _Philosophical
+    Transactions_, vol. LXX., but most remain uncalculated in my journal
+    _till some proper opportunity."[12]_
+
+While HERSCHEL was measuring these lunar mountains, in December, 1779,
+he made by chance an acquaintance of much value to him. Dr. WILLIAM
+WATSON, a Fellow of the Royal Society, distinguished for his researches
+in electricity, happened to see him at his telescope, and this led to a
+visit and an invitation to HERSCHEL to join the Philosophical Society of
+Bath, then forming. This he gladly did, and it was of use to him in many
+ways.
+
+He there formed acquaintance with men of his own way of thinking, and he
+himself became known. Better than all, he learned to measure himself
+with other men, and by his early papers read to the Society, he gained
+skill in putting his thoughts before his hearers. This skill he never
+lost, and the merely literary art of his memoirs would make his papers
+remarkable without their other merits. He is always clear, and in his
+early papers especially, he appeals to his particular audience--the
+Royal Society--in a way which shows that he is conscious of all its
+weaknesses as well as of its dignity. Later, his tone slightly changed.
+He became less anxious to win his audience, for he had become an
+authority. This knowledge lent a quiet strength to his style, but never
+induced the slightest arrogance of spirit or manner.
+
+The Bath Philosophical Society has left no printed proceedings. HERSCHEL
+was one of its earliest members, and many papers were communicated to it
+by his hand. These appear to have been of a very miscellaneous nature.
+Some of them at least would be of the highest interest to us now.
+
+In the _Philosophical Transactions_ for 1789, p. 220, HERSCHEL tells us
+that he communicated to that Society "certain mathematical papers"
+relating to central forces other than the force of gravity, which are or
+may be concerned in the construction of the sidereal heavens. This early
+idea was still entertained by HERSCHEL in 1789, and the mathematical
+papers referred to must be contained in the _Minutes_ of the Society,
+which on its dissolution were torn from the Minute-book and returned to
+the writers.
+
+The earliest published writing of HERSCHEL is the answer to the prize
+question in the "Ladies' Diary" for 1779, proposed by the celebrated
+LANDEN, namely:
+
+    "The length, tension, and weight of a musical string being given,
+    it is required to find how many vibrations it will make in a given
+    time, when a small given weight is fastened to its middle and
+    vibrates with it."
+
+In the _Philosophical Transactions_ of the Royal Society for 1780, are
+two papers of his. The title of the first is, _Astronomical Observations
+on the Periodical Star in Collo Ceti_, by Mr. WILLIAM HERSCHEL, of Bath.
+This was communicated to the Society by Dr. WILLIAM WATSON, Jr., and
+was read May 11, 1780, at the same time as the other paper on the
+mountains of the moon. It is to be noted that HERSCHEL was at this time
+plain "Mr. WILLIAM HERSCHEL, of Bath." It was only in 1786 that he
+became "Dr. HERSCHEL," through the Oxford degree of LL.D.
+
+Neither of these two papers is specially remarkable on its purely
+astronomical side. The problems examined were such as lay open before
+all, and the treatment of them was such as would naturally be suggested.
+
+The second of these two contained, however, a short description of his
+Newtonian telescope, and he speaks of it with a just pride: "I believe
+that for distinctness of vision this instrument is perhaps equal to any
+that was ever made." He was, at least, certain of having obtained
+excellence in the making of his instruments.
+
+In his next paper, however, read January 11, 1781, a subject is
+approached which shows a different kind of thought. It is the first
+obvious proof of the truth of the statement which he made long
+afterwards (1811), when he said: "A knowledge of the construction of
+the heavens has always been the ultimate object of my observations."
+
+The title of this paper was _Astronomical Observations on the Rotation
+of the Planets round their Axes, made with a view to determine whether
+the Earth's diurnal motion is perfectly equable_. Here the question is a
+difficult and a remote one, and the method adopted for its solution is
+perfectly suitable in principle. It marks a step onward from mere
+observations to philosophizing upon their results. In practical
+astronomy, too, we note an advance. Not only are his results given, but
+also careful estimates of the errors to be feared in them, and a
+discussion of the sources of such errors. The same volume of the
+_Philosophical Transactions_ which contains this paper, also contains
+another, _Account of a Comet_, read April 26, 1781. This comet was the
+major planet _Uranus_, or, as HERSCHEL named it, _Georgium Sidus_.
+He had found it on the night of Tuesday, March 13, 1781. "In examining
+the small stars in the neighborhood of H _Geminorum_, I perceived one that
+appeared visibly larger than the rest; being struck with its uncommon
+appearance, I compared it to H _Geminorum_ and the small star in the
+quartile between _Auriga_ and _Gemini_, and finding it so much larger
+than either of them, I suspected it to be a comet." The "comet" was
+observed over all Europe. Its orbit was computed by various astronomers,
+and its distance from the sun was found to be nineteen times that of our
+earth. This was no comet, but a new major planet. The discovery of the
+amateur astronomer of Bath was the most striking since the invention of
+the telescope. It had absolutely no parallel, for every other major
+planet had been known from time immemorial.[13]
+
+The effect of the discoveries of GALILEO was felt almost more in the
+moral than in the scientific world. The mystic number of the planets was
+broken up by the introduction of four satellites to _Jupiter_. That
+_Venus_ emulated the phases of our moon, overthrew superstition and
+seated the Copernican theory firmly. The discovery of "an innumerable
+multitude of fixed stars" in the Milky Way confounded the received
+ideas. This was the great mission of the telescope in GALILEO'S hands.
+
+The epoch of mere astronomical discovery began with the detection of the
+large satellite of _Saturn_ by HUYGHENS, in 1655. Even then superstition
+was not dead. HUYGHENS did not search for more moons, because by that
+discovery he had raised the number of known satellites to six,[14] and
+because these, with the six planets, made "the perfect number twelve."
+
+From 1671 to 1684 CASSINI discovered four more moons revolving about
+_Saturn_. Since 1684 no new body had been added to the solar system.
+It was thought complete for nearly a century.
+
+In England, the remarkable discoveries of BRADLEY (1727-62) had been in
+the field of practical astronomy, and his example had set the key-note
+for further researches. France was just about beginning the brilliant
+period of her discoveries in mathematical astronomy, and had no
+observatory devoted to investigations like HERSCHEL'S, with the possible
+exception of DARQUIER'S and FLAUGERGUES'. The observatories of SCHROETER
+and VON HAHN, in Germany, were not yet active. The field which HERSCHEL
+was created to fill was vacant, the whole world over. It was especially
+so in England. The Royal Observatory at Greenwich, under MASKELYNE,
+a skilful observer, whose work was mostly confined to meridian
+observations, was no rival to a private observatory like HERSCHEL'S. The
+private observatories themselves were but small affairs; those of the
+king, at Kew, of Dr. WILSON, at Glasgow, of Mr. AUBERT, at Loampit Hill,
+of the Count VON BRUHL, in London, being perhaps the most important.
+The whole field was open. What was perhaps more remarkable, there was in
+England, during HERSCHEL'S lifetime, no astronomer, public or private,
+whose talents, even as an observer, lay in the same direction.
+
+It hardly need be said that as a philosopher in his science, he had then
+no rival, as he has had none since. His only associates even, were
+MICHELL and WILSON.[15]
+
+Without depreciating the abilities of the astronomers of England, his
+cotemporaries, we may fairly say that HERSCHEL stood a great man among a
+group of small ones.
+
+Let us endeavor to appreciate the change effected in the state of
+astronomy not only in England but in the whole world, simply by the
+discovery of _Uranus_. Suppose, for example, that the last planet in our
+system had been _Saturn_. No doubt HERSCHEL would have gone on. In spite
+of one and another difficulty, he would have made his ten-foot, his
+twenty-foot telescopes. His forty-foot would never have been built, and
+the two satellites which he found with it might not have been
+discovered. Certainly _Mimas_ would not have been. His researches on the
+construction of the heavens would have been made; those were in his
+brain, and must have been ultimated. The mass of observations of
+_Saturn_, of _Jupiter_, of _Mars_, of _Venus_, would have been made and
+published. The researches on the sun, on the "invisible rays" of heat,
+on comets and nebulae--all these might have been made, printed, and read.
+
+But these would have gone into the _Philosophical Transactions_ as the
+work of an amateur astronomer, "Mr. HERSCHEL, of Bath." They would have
+been praised, and they would have been doubted. It would have taken a
+whole generation to have appreciated them. They would have been severely
+tried, entirely on their merits, and finally they would have stood where
+they stand to-day--unrivalled. But through what increased labors these
+successes would have been gained! It is not merely that the patronage of
+the king, the subsidies for the forty-foot telescope (L4,000), the
+comparative ease of HERSCHEL'S life would have been lacking. It is more
+than this. It would have been necessary for him to have created the
+audience to which he appealed, and to have conquered the most persistent
+of enemies--indifference.
+
+Certainly, if HERSCHEL'S mind had been other than it was, the discovery
+of _Uranus_, which brought him honors from every scientific society in
+the world, and which gave him authority, might have had a hurtful
+effect. But, as he was, there was nothing which could have aided his
+career more than this startling discovery. It was needed for him. It
+completed the solar system far more by affording a free play to a
+profoundly philosophical mind, than by occupying the vacant spaces
+beyond _Saturn_.
+
+His opportunities would have been profoundly modified, though his
+personal worth would have been the same.
+
+    "The Star that from the zenith darts its beams,
+    Visible though it be to half the earth,
+    Though half a sphere be conscious of its brightness,
+    Is yet of no diviner origin,
+    No purer essence, than the One that burns
+    Like an untended watchfire, on the ridge
+    Of some dark mountain; or than those that seem
+    Humbly to hang, like twinkling winter lamps,
+    Among the branches of the leafless trees."
+
+To show how completely unknown the private astronomer of Bath was at
+this time, I transcribe a sentence from BODE'S account of the discovery
+of _Uranus_.
+
+    "In the _Gazette Litteraire_ of June, 1781, this worthy man is
+    called MERSTHEL; in JULIUS' _Journal Encyclopedique_, HERTSCHEL;
+    in a letter from Mr. MASKELYNE to M. MESSIER, HERTHEL; in another
+    letter of MASKELYNE'S to Herr MAYER, at Mannheim, HERRSCHELL; M.
+    DARQUIER calls him HERMSTEL. What may his name be? He must have been
+    born a _German_."[16]
+
+This obscurity did not long continue. The news spread quickly from
+fashionable Bath to London. On the 6th of December, 1781, HERSCHEL was
+elected a Fellow of the Royal Society, to which he was formally
+"admitted" May 30, 1782. He was forty-three years old.
+
+He also received the Copley medal in 1781 for his "discovery of a new
+and singular star."[17]
+
+    . . . "He was now frequently interrupted by visitors who were
+    introduced by some of his resident scholars, among whom I remember
+    Sir HARRY ENGELFIELD, Dr. BLAGDEN, and Dr. MASKELYNE. With the
+    latter he was engaged in a long conversation, which to me sounded
+    like quarrelling, and the first words my brother said after he was
+    gone were: 'That is a devil of a fellow.'. . .
+
+    "I suppose their names were often not known, or were forgotten; for
+    it was not till the year 1782 or 1783 that a memorandum of the names
+    of visitors was thought of.". . . "My brother now applied himself to
+    perfect his mirrors, erecting in his garden a stand for his
+    twenty-foot telescope; many trials were necessary before the
+    required motions for such an unwieldy machine could be contrived.
+    Many attempts were made by way of experiment before an intended
+    thirty-foot telescope could be completed, for which, between whiles
+    (not interrupting the observations with seven, ten, and twenty-foot,
+    and writing papers for both the Royal and Bath Philosophical
+    Societies), gauges, shapes, weight, etc., of the mirror were
+    calculated, and trials of the composition of the metal were made. In
+    short, I saw nothing else and heard nothing else talked of but these
+    things when my brothers were together. ALEX. was always very alert,
+    assisting when anything new was going forward, but he wanted
+    perseverance, and never liked to confine himself at home for many
+    hours together. And so it happened that my brother WILLIAM was
+    obliged to make trial of my abilities in copying for him catalogues,
+    tables, etc., and sometimes whole papers which were lent him for his
+    perusal. Among them was one by Mr. MICHELL and a catalogue of
+    CHRISTIAN MAYER, in Latin, which kept me employed when my brother
+    was at the telescope at night. When I found that a hand was
+    sometimes wanted when any particular measures were to be made with
+    the lamp micrometer, etc., or a fire to be kept up, or a dish of
+    coffee necessary during a long night's watching, I undertook with
+    pleasure what others might have thought a hardship. . . . Since the
+    discovery of the _Georgium Sidus_ [March 13, 1781], I believe few
+    men of learning or consequence left Bath before they had seen and
+    conversed with its discoverer, and thought themselves fortunate in
+    finding him at home on their repeated visits. Sir WILLIAM WATSON was
+    almost an intimate, for hardly a day passed but he had something to
+    communicate from the letters which he received from Sir JOSEPH
+    BANKS, and other members of the Royal Society, from which it
+    appeared that my brother was expected in town to receive the gold
+    medal. The end of November was the most precarious season for
+    absenting himself. But Sir WILLIAM WATSON went with him, and it was
+    arranged so that they set out with the diligence at night, and by
+    that means his absence did not last above three or four days, when
+    my brother returned alone, Sir WILLIAM remaining with his father.
+
+    "Now a very busy winter was commencing; for my brother had engaged
+    himself to conduct the oratorios conjointly with RONZINI, and had
+    made himself answerable for the payment of the engaged performers,
+    for his credit ever stood high in the opinion of every one he had to
+    deal with. (He lost considerably by this arrangement.) But, though
+    at times much harassed with business, the mirror for the thirty-foot
+    reflector was never out of his mind, and if a minute could but be
+    spared in going from one scholar to another, or giving one the slip,
+    he called at home to see how the men went on with the furnace, which
+    was built in a room below, even with the garden.
+
+    "The mirror was to be cast in a mould of loam, of which an immense
+    quantity was to be pounded in a mortar and sifted through a fine
+    sieve. It was an endless piece of work, and served me for many an
+    hour's exercise; and ALEX. frequently took his turn at it, for we
+    were all eager to do something towards the great undertaking. Even
+    Sir WILLIAM WATSON would sometimes take the pestle from me when he
+    found me in the work-room, where he expected to find his friend, in
+    whose concerns he took so much interest that he felt much
+    disappointed at not being allowed to pay for the metal. But I do not
+    think my brother ever accepted pecuniary assistance from any one of
+    his friends, and on this occasion he declined the offer by saying it
+    was paid for already.
+
+    "Among the Bath visitors were many philosophical gentlemen who used
+    to frequent the levees at St. James's, when in town. Colonel WALSH,
+    in particular, informed my brother that from a conversation he had
+    had with His Majesty, it appeared that in the spring he was to come
+    with his seven-foot telescope to the king. Similar reports he
+    received from many others, but they made no great impression nor
+    caused any interruption in his occupation or study, and as soon as
+    the season for the concerts was over, and the mould, etc., in
+    readiness, a day was set apart for casting, and the metal was in the
+    furnace. Unfortunately it began to leak at the moment when ready for
+    pouring, and both my brothers and the caster, with his men, were
+    obliged to run out at opposite doors, for the stone flooring (which
+    ought to have been taken up) flew about in all directions as high as
+    the ceiling. Before the second casting was attempted, everything
+    which could insure success had been attended to, and a very perfect
+    metal was found in the mould.
+
+    "But a total stop and derangement now took place, and nearly six or
+    seven months elapsed before my brother could return to the
+    undisturbed enjoyment of his instruments and observations. For one
+    morning in Passion Week, as Sir WILLIAM WATSON was with my brother,
+    talking about the pending journey to town, my eldest nephew arrived
+    to pay us a visit, and brought the confirmation that his uncle was
+    expected with his instrument in town. . . . We had not one night in
+    the week, except Friday, but what was set apart for an oratorio either
+    at Bath or Bristol. Soon after Easter, a new organ being erected in
+    St. James's Church, it was opened with two performances of the
+    'Messiah;' this again took up some of my brother's time.". . .
+
+In May of 1782 HERSCHEL went to London.
+
+    "But when almost double the time had elapsed which my brother could
+    safely be absent from his scholars, ALEX., as well as myself, were
+    much at a loss how to answer their inquiries, for, from the letters
+    we received, we could learn nothing but that he had been introduced
+    to the king and queen, and had permission to come to the concerts at
+    Buckingham House, where the king conversed with him about
+    astronomy."
+
+It was during his absence at this time that the three following letters
+were written and received:
+
+    "DEAR LINA:--
+
+    "I have had an audience of His Majesty this morning, and met with a
+    very gracious reception. I presented him with the drawing of the
+    solar system, and had the honor of explaining it to him and the
+    queen. My telescope is in three weeks' time to go to Richmond, and
+    meanwhile to be put up at Greenwich, where I shall accordingly carry
+    it to-day. So you see, LINA, that you must not think of seeing me in
+    less than a month. I shall write to Miss LEE myself; and other
+    scholars who inquire for me, you may tell that I cannot wait on them
+    till His Majesty shall be pleased to give me leave to return, or
+    rather to dismiss me, for till then I must attend. I will also write
+    to Mr. PALMER to acquaint him with it.
+
+    "I am in a great hurry, therefore can write no more at present.
+    Tell ALEXANDER that everything looks very likely as if I were to stay
+    here. The king inquired after him, and after my great speculum. He
+    also gave me leave to come to hear the GRIESBACHS play at the
+    private concert which he has every evening. My having seen the king
+    need not be kept a secret, but about my staying here it will be best
+    not to say anything, but only that I must remain here till His
+    Majesty has observed the planets with my telescope.
+
+    "Yesterday I dined with Colonel WALSH, who inquired after you. There
+    were Mr. AUBERT and Dr. MASKELYNE. Dr. MASKELYNE in public declared
+    his obligations to me for having introduced to them the high powers,
+    for Mr. AUBERT has so much succeeded with them that he says he looks
+    down upon 200, 300, or 400 with contempt, and immediately begins
+    with 800. He has used 2,500 very completely, and seen my fine double
+    stars with them. All my papers are printing, with the postscript and
+    all, and are allowed to be very valuable. You see, LINA, I tell you
+    all these things. You know vanity is not my foible, therefore I need
+    not fear your censure. Farewell.
+
+                   "I am, your affectionate brother,
+
+                                           "WM. HERSCHEL.
+
+
+    "Saturday Morning,
+
+         "probably _May 25, 1782_."
+
+                    TO MISS HERSCHEL.
+
+                                    "Monday Evening, _June 3, 1782._
+
+    "DEAR LINA:--
+
+    "I pass my time between Greenwich and London agreeably enough,
+    but am rather at a loss for work that I like. Company is not always
+    pleasing, and I would much rather be polishing a speculum. Last
+    Friday I was at the king's concert to hear GEORGE play. The king
+    spoke to me as soon as he saw me, and kept me in conversation for
+    half an hour. He asked GEORGE to play a solo-concerto on purpose
+    that I might hear him; and GEORGE plays extremely well, is very much
+    improved, and the king likes him very much. These two last nights I
+    have been star-gazing at Greenwich with Dr. MASKELYNE and Mr.
+    AUBERT. We have compared our telescopes together, and mine was found
+    very superior to any of the Royal Observatory. Double stars which
+    they could not see with their instruments I had the pleasure to show
+    them very plainly, and my mechanism is so much approved of that
+    Dr. MASKELYNE has already ordered a model to be taken from mine,
+    and a stand to be made by it to his reflector. He is, however, now
+    so much out of love with his instrument that he begins to doubt
+    whether it _deserves_ a new stand.
+
+    "I am introduced to the best company. To-morrow I dine at Lord
+    PALMERSTON'S, next day with Sir JOSEPH BANKS, etc., etc. Among
+    opticians and astronomers nothing now is talked of but _what they
+    call_ my great discoveries. Alas! this shows how far they are
+    behind, when such trifles as I have seen and done are called
+    _great_. Let me but get at it again! I will make such telescopes,
+    and see such things--that is, I will endeavor to do so."
+
+
+                         TO MISS HERSCHEL.
+
+                                                     "_July 3, 1782._"
+
+    "DEAR CAROLINA:--
+
+    "I have been so much employed that you will not wonder at my not
+    writing sooner. The letter you sent me last Monday came very safe to
+    me. As Dr. WATSON has been so good as to acquaint you and ALEXANDER
+    with my situation, I was still more easy in my silence to you. Last
+    night the King, the Queen, the Prince of Wales, the Princess Royal,
+    Princess SOPHIA, Princess AUGUSTA, etc., Duke of MONTAGUE, Dr.
+    HEBERDEN, M. DE LUC, etc., etc., saw my telescope, and it was a very
+    fine evening. My instrument gave general satisfaction. The king has
+    very good eyes, and enjoys observations with telescopes exceedingly.
+
+    "This evening, as the king and queen are gone to Kew, the princesses
+    were desirous of seeing my telescope, but wanted to know if it was
+    possible to see without going out on the grass, and were much
+    pleased when they heard that my telescope could be carried into any
+    place they liked best to have it. About eight o'clock it was moved
+    into the queen's apartments, and we waited some time in hopes of
+    seeing _Jupiter_ or _Saturn_. Meanwhile I showed the princesses, and
+    several other ladies who were present, the speculum, the
+    micrometers, the movements of the telescopes, and other things that
+    seemed to excite their curiosity. When the evening appeared to be
+    totally unpromising, I proposed an artificial _Saturn_ as an object,
+    since we could not have the real one. I had beforehand prepared this
+    little piece, as I guessed by the appearance of the weather in the
+    afternoon we should have no stars to look at. This being accepted
+    with great pleasure, I had the lamps lighted up which illuminated
+    the picture of a _Saturn_ (cut out in pasteboard) at the bottom of
+    the garden wall. The effect was fine, and so natural that the best
+    astronomer might have been deceived. Their royal highnesses and
+    other ladies seemed to be much pleased with the artifice.
+
+    "I remained in the queen's apartment with the ladies till about half
+    after ten; when in conversation with them I found them extremely
+    well instructed in every subject that was introduced, and they
+    seemed to be most amiable characters. To-morrow evening they hope to
+    have better luck, and nothing will give me greater happiness than to
+    be able to show them some of those beautiful objects with which the
+    heavens are so gloriously ornamented."
+
+CAROLINA'S diary goes on:
+
+    "Sir WILLIAM WATSON returned to Bath after a fort-night or three
+    weeks' stay. From him we heard that my brother was invited to
+    Greenwich with the telescope, where he was met by a numerous party
+    of astronomical and learned gentlemen, and trials of his instrument
+    were made. In these letters he complained of being obliged to lead
+    an idle life, having nothing to do but to pass between London and
+    Greenwich. Sir WILLIAM received many letters, which he was so kind
+    as to communicate to us. By these, and from those to ALEXANDER or to
+    me, we learned that the king wished to see the telescope at Windsor.
+    At last a letter, dated July 2, arrived from THERESE, and from this
+    and several succeeding ones we gathered that the king would not
+    suffer my brother to return to his profession again, and by his
+    writing several times for a supply of money we could only suppose
+    that he himself was in uncertainty about the time of his return.
+
+    "In the last week of July my brother came home, and immediately
+    prepared for removing to Datchet, where he had taken a house with a
+    garden and grass-plat annexed, quite suitable for the purpose of an
+    observing-place. Sir WILLIAM WATSON spent nearly the whole time at
+    our house, and he was not the only friend who truly grieved at my
+    brother's going from Bath; or feared his having perhaps agreed to no
+    very advantageous offers; their fears were, in fact, not without
+    reason. . . . The prospect of entering again on the toils of teaching,
+    etc., which awaited my brother at home (the months of leisure being
+    now almost gone by), appeared to him an intolerable waste of time,
+    and by way of alternative he chose to be royal astronomer, with a
+    salary of L200 a year. Sir WILLIAM WATSON was the only one to whom
+    the sum was mentioned, and he exclaimed, 'Never bought monarch honor
+    so cheap!' To every other inquirer, my brother's answer was that the
+    king had provided for him."
+
+On the 1st of August, 1782, the family removed to Datchet. The last
+musical duty was performed on Whit-Sunday, 1782, in St. Margaret's
+Chapel, Bath, when the anthem for the day was of HERSCHEL'S own
+composition.
+
+The end of the introductory epoch of his life is reached. Henceforth he
+lived in his observatory, and from his forty-fourth year onwards he only
+left it for short periods to go to London to submit his classic memoirs
+to the Royal Society. Even for these occasions he chose periods of
+moonlight, when no observations could be made.
+
+He was a private man no longer. Henceforth he belongs to the whole
+world.
+
+FOOTNOTES:
+
+[10] Probably on the model of one of SHORT'S Gregorian
+telescopes, which were then the best instruments of the kind.
+
+[11] For a description of the main points of HERSCHEL'S
+processes of making reflectors, which will illustrate his strong
+mechanical talents, see _Encyclopaedia Britannica_, eighth edition,
+article _Telescope_.
+
+[12] These have never been published, nor is it likely at this
+day, when our measuring instruments are so greatly improved, that they
+would be of any material value to science, although of interest as
+giving the proofs of HERSCHEL'S assiduity and skill. He was always more
+than the maker of telescopes, for he was never content until they were
+applied to the problems of astronomy.
+
+[13] ARAGO has implied that if HERSCHEL had directed his
+telescope to _Uranus_ only eleven days earlier than he did, this
+discovery would have escaped him, since at that time (March 2, 1781) the
+planet was at its _station_, and had no motion relative to the star.
+This is an entire misconception, since the new planet was detected by
+its physical appearance, and not by its motion. Does any one suppose
+that "a new and singular star" like this would have been once viewed and
+then forgotten?
+
+[14] Four of _Jupiter_, one of the earth, and one of _Saturn_.
+
+[15] JOHN MICHELL had been a member of the Royal Society since
+1760: he died in 1793. He was a philosophical thinker, as is shown by
+his memoirs on the distances of the stars, and by his invention of the
+method for determining the earth's density. It is not certain that he
+was personally known to HERSCHEL, although his writings were familiar to
+the latter.
+
+ALEXANDER WILSON was Professor of Astronomy at Glasgow, and is chiefly
+known to us by his theory of the nature of the solar spots, which was
+adopted and enlarged by HERSCHEL. He died in 1786; but the families of
+WILSON and HERSCHEL remained close friends.
+
+[16] _Berliner Jahrbuch_, 1784, p. 211. In the _Connaissance
+des Tems_ for 1784 he is called "HOROCHELLE."
+
+[17] At the presentation Sir JOSEPH BANKS, the President of the
+Royal Society, said: "In the name of the Royal Society I present to you
+this gold medal, the reward which they have assigned to your successful
+labors, and I exhort you to continue diligently to cultivate those
+fields of science which have produced to you a harvest of so much honor.
+Your attention to the improvement of telescopes has already amply repaid
+the labor which you have bestowed upon them; but the treasures of the
+heavens are well known to be inexhaustible. Who can say but your new
+star, which exceeds _Saturn_ in its distance from the sun, may exceed
+him as much in magnificence of attendance? Who knows what new rings, new
+satellites, or what other nameless and numberless phenomena remain
+behind, waiting to reward future industry and improvement?"
+
+
+
+
+                             CHAPTER III.
+
+            LIFE AT DATCHET, CLAY HALL, AND SLOUGH; 1782-1822.
+
+
+The new house at Datchet, which was occupied from 1782 till 1785, was a
+source of despair to CAROLINA HERSCHEL, who looked upon its desolate and
+isolated condition with a housekeeper's eyes. This was nothing to her
+brother, who gayly consented to live upon "eggs and bacon," now that he
+was free at last to mind the heavens. The ruinous state of the place had
+no terrors in his eyes, for was there not a laundry which would serve as
+a library, a large stable which was just the place for the grinding of
+mirrors, and a grass-plat for the small twenty-foot reflector?
+
+Here they set to work at astronomy; the brother with the twenty-foot,
+the sister aiding him, and at odd times sweeping for comets. In the
+course of her life she discovered no less than eight, and five of these
+were first seen by her.
+
+       *       *       *       *       *
+
+In 1787 HERSCHEL wrote his paper "On three Volcanoes in the Moon,"
+which he had observed in April of that year. In this he mentions
+previous observations of the same sort. I do not remember that the
+following account of these has ever been put on record in English.
+Baron VON ZACH writes from London to BODE:[18]
+
+    "Probably you have heard also of the volcanoes in the moon, which
+    HERSCHEL has observed. . . . I will give you an account of it as I
+    heard it from his own lips. Dr. LIND, a worthy physician in Windsor,
+    who has made himself known through his two journeys in China, and
+    who is a friend of our HERSCHEL'S, was with his wife one evening on
+    a visit to HERSCHEL in Datchet [1783, May 4]. On this evening there
+    was to be an occultation of a star at the moon's dark limb. This was
+    observed by HERSCHEL and Doctor LIND. Mrs. LIND wished also to see
+    what was occurring, and placed herself at a telescope and watched
+    attentively.
+
+    "Scarcely had the star disappeared before Mrs. LIND thought she saw
+    it again, and exclaimed that the star had gone in front of, and not
+    behind the moon. This provoked a short astronomical lecture on the
+    question, but still she would not credit it, because she _saw_
+    differently. Finally HERSCHEL stepped to the telescope, and in fact
+    he saw a bright point on the dark disc of the moon, which he
+    followed attentively. It gradually became fainter and finally
+    vanished.". . .
+
+The life at Datchet was not free from its annoyances.
+
+    "Much of my brother's time was taken up in going, when the evenings
+    were clear, to the queen's lodge, to show the king, etc., objects
+    through the seven-foot. But when the days began to shorten, this was
+    found impossible, for the telescope was often (at no small expense
+    and risk of damage) obliged to be transported in the dark back to
+    Datchet, for the purpose of spending the rest of the night with
+    observations on double stars for a second catalogue. My brother was,
+    besides, obliged to be absent for a week or ten days, for the
+    purpose of bringing home the metal of the cracked thirty-foot
+    mirror, and the remaining materials from his work-room. Before the
+    furnace was taken down at Bath, a second twenty-foot mirror, twelve
+    inches diameter, was cast, which happened to be very fortunate, for
+    on the 1st of January, 1783, a very fine one cracked by frost in the
+    tube.
+
+    . . . "In my brother's absence from home I was, of course, left alone
+    to amuse myself with my own thoughts, which were anything but
+    cheerful. I found I was to be trained for an assistant astronomer,
+    and, by way of encouragement, a telescope adapted for 'sweeping,'
+    consisting of a tube with two glasses, such as are commonly used in
+    a 'finder,' was given me. I was 'to sweep for comets,' and I see, by
+    my journal, that I began August 22d, 1782, to write down and
+    describe all remarkable appearances I saw in my 'sweeps,' which were
+    horizontal. But it was not till the last two months of the same year
+    that I felt the least encouragement to spend the star-light nights
+    on a grass-plot covered with dew or hoar-frost, without a human
+    being near enough to be within call. I knew too little of the real
+    heavens to be able to point out every object so as to find it again,
+    without losing much time by consulting the Atlas. But all these
+    troubles were removed when I knew my brother to be at no great
+    distance making observations, with his various instruments, on
+    double stars, planets, etc., and when I could have his assistance
+    immediately if I found a nebula or cluster of stars, of which I
+    intended to give a catalogue; but, at the end of 1783, I had only
+    marked fourteen, when my sweeping was interrupted by being employed
+    to write down my brother's observations with the large twenty-foot.
+    I had, however, the comfort to see that my brother was satisfied
+    with my endeavors to assist him when he wanted another person either
+    to run to the clocks, write down a memorandum, fetch and carry
+    instruments, or measure the ground with poles, etc., etc., of which
+    something of the kind every moment would occur. For the assiduity
+    with which the measurements on the diameter of the _Georgium Sidus_,
+    and observations of other planets, double stars, etc., etc., were
+    made, was incredible, as may be seen by the various papers that were
+    given to the Royal Society in 1783, which papers were written in the
+    daytime, or when cloudy nights interfered. Besides this, the
+    twelve-inch speculum was perfected before the spring, and many hours
+    were spent at the turning-bench, as not a night clear enough for
+    observing ever passed but that some improvements were planned for
+    perfecting the mounting and motions of the various instruments then
+    in use, or some trials were made of new constructed eye-pieces,
+    which were mostly executed by my brother's own hands. Wishing to
+    save his time, he began to have some work of that kind done by a
+    watchmaker who had retired from business and lived on Datchet
+    Common; but the work was so bad, and the charges so unreasonable,
+    that he could not be employed. It was not till some time afterwards,
+    in his frequent visits to the meetings of the Royal Society (made in
+    moonlight nights), that he had an opportunity of looking about for
+    mathematical workmen, opticians, and founders. But the work seldom
+    answered expectation, and it was kept, to be executed with
+    improvements by ALEXANDER during the few months he spent with us.
+
+    "The summer months passed in the most active preparation for getting
+    the large twenty-foot ready against the next winter. The carpenters
+    and smiths of Datchet were in daily requisition, and, as soon as
+    patterns for tools and mirrors were ready, my brother went to town
+    to have them cast, and, during the three or four months ALEXANDER
+    could be absent from Bath, the mirrors and optical parts were nearly
+    completed.
+
+    "But that the nights after a day of toil were not given to rest, may
+    be seen by the observations on _Mars_, of which a paper, dated
+    December 1, 1783, was given to the Royal Society. Some trouble,
+    also, was often thrown away, during those nights, in the attempt to
+    teach me to remeasure double stars with the same micrometers with
+    which former measures had been taken, and the small twenty-foot was
+    given me for that purpose. . . . I had also to ascertain their places
+    by a transit instrument lent for that purpose by Mr. DALRYMPLE; but,
+    after many fruitless attempts, it was seen that the instrument was,
+    perhaps, as much in fault as my observations."
+
+In 1783 HERSCHEL says:
+
+    "I have now finished my third review of the heavens. The first was
+    made with a Newtonian telescope something less than seven feet focal
+    length, a power of 222, and an aperture of four and a half inches.
+    It extended only to stars of the first, second, third, and fourth
+    magnitudes. My second review was made with an instrument much
+    superior to the other, of 85.2 inches focus, 6.2 inches aperture,
+    and power 227. It extended to all the stars of HARRIS'S maps and
+    the telescopic ones near them, as far as the eighth magnitude. The
+    Catalogue of Double Stars and the discovery of the _Georgium Sidus_,
+    were the results of that review. The third was with the same
+    instrument and aperture, but with a power of 460. This review
+    extended to all the stars of FLAMSTEED'S Catalogue, together with
+    every small star about them, to the amount of a great many thousands
+    of stars. I have, many a night, in the course of eleven or twelve
+    hours of observation, carefully and singly examined not less than
+    400 celestial objects, besides taking measures, and sometimes
+    viewing a particular star for half an hour together."
+
+The fourth review began with the twenty-foot, in 1784.
+
+    "My brother began his series of sweeps when the instrument was yet
+    in a very unfinished state, and my feelings were not very
+    comfortable when every moment I was alarmed by a crack or fall,
+    knowing him to be elevated fifteen feet or more on a temporary
+    cross-beam, instead of a safe gallery. The ladders had not even
+    their braces at the bottom; and one night, in a very high wind, he
+    had hardly touched the ground before the whole apparatus came down.
+    Some laboring men were called up to help in extricating the mirror,
+    which was, fortunately, uninjured, but much work was cut out for
+    carpenters next day. I could give a pretty long list of accidents
+    which were near proving fatal to my brother as well as myself. To
+    make observations with such large machinery, where all around is in
+    darkness, is not unattended with danger, especially when personal
+    safety is the last thing with which the mind is occupied; even poor
+    PIAZZI did not go home without getting broken shins by falling over
+    the rack-bar.
+
+    "In the long days of the summer months many ten and seven foot
+    mirrors were finished; there was nothing but grinding and polishing
+    to be seen. For ten-foot, several had been cast with ribbed backs,
+    by way of experiment, to reduce the weight in large mirrors. In my
+    leisure hours I ground seven-foot and plain mirrors from rough to
+    fining down, and was _indulged_ with polishing and the last
+    finishing of a very beautiful mirror for Sir WILLIAM WATSON.
+
+    "An account of the discoveries made with the twenty-foot and the
+    improvements of the mechanical parts of the instrument during the
+    winter of 1785 is given with the catalogue of the first 1,000 new
+    nebulae. By which account it must plainly appear that the expenses of
+    these improvements, and those which were yet to be made in the
+    apparatus of the twenty-foot (which, in fact, proved to be a model
+    of a larger instrument), could not be supplied out of a salary of
+    L200 a year, especially as my brother's finances had been too much
+    reduced during the six months before he received his _first_
+    quarterly payment of _fifty pounds_ (which was Michaelmas, 1782).
+    Travelling from Bath to London, Greenwich, Windsor, backwards and
+    forwards, transporting the telescope, etc., breaking up his
+    establishment at Bath and forming a new one near the court, all
+    this, even leaving such personal conveniences as he had for many
+    years been used to, out of the question, could not be obtained for a
+    trifle; a good large piece of ground was required for the use of the
+    instruments, and a habitation in which he could receive and offer a
+    bed to an astronomical friend, was necessary after a night's
+    observation.
+
+    "It seemed to be supposed that enough had been done when my brother
+    was enabled to leave his profession that he might have time to make
+    and sell telescopes. The king ordered four ten-foot himself, and
+    many seven-foot besides had been bespoke, and much time had already
+    been expended on polishing the mirrors for the same. But all this
+    was only retarding the work of a thirty or forty foot instrument,
+    which it was my brother's chief object to obtain as soon as
+    possible; for he was then on the wrong side of forty-five, and felt
+    how great an injustice he would be doing to himself and to the cause
+    of astronomy by giving up his time to making telescopes for other
+    observers.
+
+    "Sir WILLIAM WATSON, who often in the lifetime of his father came to
+    make some stay with us at Datchet, saw my brother's difficulties,
+    and expressed great dissatisfaction. On his return to Bath he met,
+    among the visitors there, several belonging to the court, to whom he
+    gave his opinion concerning his friend and his situation very
+    freely. In consequence of this, my brother had soon after, through
+    Sir J. BANKS, the promise that L2,000 would be granted for enabling
+    him to make himself an instrument.
+
+    "Immediately every preparation for beginning the great work
+    commenced. A very ingenious smith (CAMPION), who was seeking
+    employment, was secured by my brother, and a temporary forge erected
+    in an upstairs room."
+
+The sale of these telescopes of HERSCHEL'S must have produced a large
+sum, for he had made before 1795 more than two hundred seven-feet, one
+hundred and fifty ten-feet, and eighty twenty-feet mirrors. For many of
+the telescopes sent abroad no stands were constructed. The mirrors and
+eye-pieces alone were furnished, and a drawing of the stand sent with
+them by which the mirrors could be mounted.
+
+In 1785 the cost of a seven-foot telescope, six and four-tenths inches
+aperture, stand, eye-pieces, etc., complete, was two hundred guineas, a
+ten-foot was six hundred guineas, and a twenty-foot about 2,500 to 3,000
+guineas. He had made four ten-foot telescopes like this for the king.
+In 1787 SCHROETER got the mirrors and eye-pieces only for a
+four-and-three-quarter-inch reflector for five guineas; those for his
+seven-foot telescope were twenty-three guineas. Later a seven-foot
+telescope, complete, was sold for one hundred guineas, and the
+twenty-five-foot reflector, made for the Madrid observatory, cost them
+75,000 francs = $15,000.[19] It was ordered in 1796, but not delivered
+for several years, the Spanish government being short of money. For a
+ten and a seven foot telescope, the Prince of Canino paid L2,310.
+
+VON MAGELLAN writes to BODE concerning a visit to HERSCHEL:[20]
+
+    "I spent the night of the 6th of January at HERSCHEL'S, in Datchet,
+    near Windsor, and had the good luck to hit on a fine evening. He has
+    his twenty-foot Newtonian telescope in the open air and mounted in
+    his garden very simply and conveniently. It is moved by an
+    assistant, who stands below it. . . . Near the instrument is a clock
+    regulated to sidereal time. . . . In the room near it sits HERSCHEL'S
+    sister, and she has FLAMSTEED'S Atlas open before her. As he gives
+    her the word, she writes down the declination and right ascension
+    and the other circumstances of the observation. In this way
+    HERSCHEL examines the whole sky without omitting the least part. He
+    commonly observes with a magnifying power of one hundred and fifty,
+    and is sure that after four or five years he will have passed in
+    review every object above our horizon. He showed me the book in
+    which his observations up to this time are written, and I am
+    astonished at the great number of them. Each sweep covers 2 deg. 15'
+    in declination, and he lets each star pass at least three times through
+    the field of his telescope, so that it is impossible that anything
+    can escape him. He has already found about 900 double stars and
+    almost as many nebulae. I went to bed about one o'clock, and up to
+    that time, he had found that night four or five new nebulae. The
+    thermometer in the garden stood at 13 deg. Fahrenheit; but, in spite of
+    this, HERSCHEL observes the whole night through, except that he
+    stops every three or four hours and goes in the room for a few
+    moments. For some years HERSCHEL has observed the heavens every hour
+    when the weather is clear, and this always in the open air, because
+    he says that the telescope only performs well when it is at the same
+    temperature as the air. He protects himself against the weather by
+    putting on more clothing. He has an excellent constitution, and
+    thinks about nothing else in the world but the celestial bodies. He
+    has promised me in the most cordial way, entirely in the service of
+    astronomy, and without thinking of his own interest, to see to the
+    telescopes I have ordered for European observatories, and he will
+    himself attend to the preparation of the mirrors."
+
+It was at this time, 1783, May 8, that HERSCHEL married. His wife was
+the daughter of Mr. JAMES BALDWIN, a merchant of the city of London, and
+the widow of JOHN PITT, Esq. She is described as a lady of singular
+amiability and gentleness of character. She was entirely interested in
+his scientific pursuits, and the jointure which she brought removed all
+further anxiety about money affairs. They had but one child, JOHN
+FREDERICK WILLIAM, born March 7, 1792.[21]
+
+       *       *       *       *       *
+
+The house at Datchet became more and more unfit for the needs of the
+family, and in June, 1785, a move was made to Clay Hall, in Old Windsor.
+The residence here was but short, and finally a last change was made to
+Slough on April, 3d, 1786.
+
+The ardor of the work during these years can be judged of by a single
+sentence from CAROLINA HERSCHEL'S diary:
+
+    "The last night at Clay Hall was spent in sweeping till daylight,
+    and by the next evening the telescope stood ready for observation at
+    Slough."
+
+From 1786 until his death, HERSCHEL remained at Slough; his life, truly
+speaking, was in his observatory.
+
+It is indeed true, as ARAGO has said in his eloquent tribute to him: "On
+peut dire hardiment du jardin et de la petite maison de Slough, que
+c'est le lieu du monde ou il a ete fait le plus de decouvertes. Le nom
+de ce village ne perira pas; les sciences le transmettront
+religieusement a nos derniers neveux."
+
+HERSCHEL'S first contribution to the _Philosophical Transactions_ was
+printed in the volume for 1780, his last in that for 1818. Of these
+thirty-nine volumes, there are only two (1813 and 1817) which contain no
+paper from his hand, and many volumes contain more than one, as he
+published no less than sixty-eight memoirs in this place.
+
+And yet it must not be thought that his was an austere and grave
+existence. Music, which he loved to enthusiasm, was still a delight to
+him. All the more that his devotion was free. The glimpses which we get
+of his life with his friends show him always cheerful, ardent, and
+devoted. Even in his later years, he had not lost a "boyish earnestness
+to explain;" his simplicity and the charm of his manner struck every
+one.
+
+"HERSCHEL, you know, and everybody knows, is one of the most pleasing
+and well-bred natural characters of the present age," says Dr. BURNEY,
+who had opportunity to know.
+
+The portrait which is given in the frontispiece must have been painted
+about this time (1788), and the eager, ardent face shows his inner life
+far better than any words can do.
+
+Even in his scientific writings, which everything conspired to render
+grave and sober, the almost poetic nature of his mind shows forth. In
+one of his (unpublished) note-books, now in the Royal Society's library,
+I found this entry:
+
+    "640th Sweep--November 28, 1786.--The nebula of _Orion_, which I saw
+    by the front view, was so glaring and beautiful that I could not
+    think of taking any place of its extent."
+
+He was quite alone under the perfectly silent sky when this was written,
+and he was at his post simply to make this and other such observations.
+But the sky was beautiful to him, and his faithful sister, CAROLINA,
+sitting below, has preserved for us the words as they dropped from his
+lips.
+
+On the 11th of January, 1787, HERSCHEL discovered two satellites to
+_Uranus_.
+
+After he had well assured himself of their existence, but before he
+communicated his discovery to the world, he made this crucial test. He
+prepared a sketch of _Uranus_ attended by his two satellites, as it
+would appear on the night of February 10, 1787, and when the night
+came, "the heavens displayed the original of my drawings, by showing in
+the situation I had delineated them _the Georgian planet attended by two
+satellites_. I confess that this scene appeared to me with additional
+beauty, as the little secondary planets seemed to give a dignity to the
+primary one which raises it into a more conspicuous situation among the
+great bodies of the solar system.". . .
+
+In a memoir of 1789, he has a few sentences which show the living way
+in which the heavens appeared to him:
+
+    "This method of viewing the heavens seems to throw them into a new
+    kind of light.
+
+    "They are now seen to resemble a luxuriant garden, which contains
+    the greatest variety of productions in different flourishing beds;
+    and one advantage we may at least reap from it is, that we can, as
+    it were, extend the range of our experience to an immense duration.
+    For is it not almost the same thing whether we live successively to
+    witness the germination, blooming, foliage, fecundity, fading,
+    withering, and corruption of a plant, or whether a vast number of
+    specimens selected from every stage through which the plant passes
+    in the course of its existence be brought at once to our view?"
+
+The thought here is no less finely expressed than it is profound. The
+simile is perfect, if we have the power to separate among the vast
+variety each state of being from every other, and if the very luxuriance
+of illustration in the heavens does not bewilder and overpower the mind.
+It was precisely this discriminating power that HERSCHEL possessed in
+perfection.
+
+There is a kind of humor in the way he records a change of opinion:
+
+    "I formerly supposed the surface of _Saturn's_ ring to be rough,
+    owing to luminous points like mountains seen on it, till one of
+    these was kind enough to venture off the edge of the ring and appear
+    as a satellite."
+
+In 1782 he replies with a certain concealed sharpness to the idea that
+he used magnifying powers which were too high. There is a tone almost of
+impatience, as if he were conscious he was replying to a criticism based
+on ignorance:
+
+    "We are told that we gain nothing by magnifying too much. I grant
+    it; but shall never believe I magnify too much till by experience I
+    find that I can see better with a lower power." (1782.)
+
+By 1786, when he returns to this subject, in answer to a formal request
+to explain his use of high magnifiers, he is quite over any irritation,
+and treats the subject almost with playfulness:
+
+    "Soon after my first essay of using high powers with the Newtonian
+    telescope, I began to doubt whether an opinion which has been
+    entertained by several eminent authors, 'that vision will grow
+    indistinct when the optic pencils are less than the fiftieth part of
+    an inch,' would hold good in all cases. I perceived that according
+    to this criterion I was not entitled to see distinctly with a power
+    of much more than about 320 in a seven-foot telescope of an aperture
+    of six and four-tenths inches, whereas in many experiments I found
+    myself very well pleased with magnifiers which far exceeded such
+    narrow limits. This induced me, as it were, by way of apology to
+    myself for seeing well where I ought to have seen less distinctly,
+    to make a few experiments."
+
+It is needless to say that these experiments proved that from the point
+of view taken by HERSCHEL, he was quite right, and that his high powers
+had numerous valuable applications. He goes on to say:
+
+    "Had it not been for a late conversation with some of my highly
+    esteemed and learned friends, I might probably have left the papers
+    on which these experiments were recorded, among the rest of those
+    that are laid aside, when they have afforded me the information I
+    want."
+
+The last sentence seems to be a kind of notice to his learned friends
+that there is yet more unsaid. As a warning to those to whose criticisms
+he had replied, he gives them this picture of the kind of assiduity
+which will be required, if some of his observations on double stars are
+to be repeated:
+
+    "It is in vain to look for these stars if every circumstance is not
+    favorable. The observer as well as the instrument must have been
+    long enough out in the open air to acquire the same temperature. In
+    very cold weather an hour at least will be required." (1782.)
+
+We may gain some further insight into his character from the following
+chance extracts from his writings:
+
+    "I have all along had truth and reality in view as the sole object
+    of my endeavors." (1782.)
+
+    "Not being satisfied when I thought it possible to obtain more
+    accurate measures, I employed [a more delicate apparatus]." (1783.)
+
+    "To this end I have already begun a series of observations upon
+    several zones of double stars, and should the result of them be
+    against these conjectures, I shall be the first to point out their
+    fallacy." (1783.)
+
+    "There is a great probability of succeeding still farther in this
+    laborious but delightful research, so as to be able at last to say
+    not only how much the annual parallax _is not_, but how much it
+    really _is_." (1782.)
+
+The nature of his philosophizing, and the limits which he set to
+himself, may be more clearly seen in further extracts:
+
+    "By taking more time [before printing these observations] I should
+    undoubtedly be enabled to speak more confidently of the _interior_
+    _construction of the heavens_, and of its various _nebulous_ and
+    sidereal strata. As an apology for this prematurity it may be said
+    that, the end of all discoveries being communication, we can never
+    be too ready in giving facts and observations, whatever we may be in
+    reasoning upon them." (1785.)
+
+    "In an investigation of this delicate nature we ought to avoid two
+    opposite extremes. If we indulge a fanciful imagination, and build
+    worlds of our own, we must not wonder at our going wide from the
+    path of truth and nature. On the other hand, if we add observation
+    to observation without attempting to draw not only certain
+    conclusions but also conjectural views from them, we offend against
+    the very end for which only observations ought to be made. I will
+    endeavor to keep a proper medium, but if I should deviate from that,
+    I could wish not to fall into the latter error." (1785.)
+
+    "As observations carefully made should always take the lead of
+    theories, I shall not be concerned if what I have to say contradicts
+    what has been said in my last paper on this subject." (1790.)
+
+No course of reasoning could be more simple, more exact, more profound,
+and more beautiful than this which follows:
+
+    "As it has been shown that the spherical figure of a cluster is
+    owing to the action of central powers, it follows that those
+    clusters which, _caeteris paribus_, are the most complete in this
+    figure, must have been the longest exposed to the action of these
+    causes. Thus the maturity of a sidereal system may be judged from
+    the disposition of the component parts.
+
+    "Hence planetary nebulae may be looked on as very aged. Though we
+    cannot see any individual nebula pass through all its stages of
+    life, we can select particular ones in each peculiar stage." (1789.)
+
+There is something almost grandiose and majestic in his statement of
+the ultimate destiny of the Galaxy:
+
+                  "To him the fates were known
+             Of orbs dim hovering on the skirts of space."
+
+    "--Since the stars of the Milky Way are permanently exposed to the
+    action of a power whereby they are irresistibly drawn into groups,
+    we may be certain that from mere clustering stars they will be
+    gradually compressed, through successive stages of accumulation,
+    till they come up to what may be called the ripening period of the
+    globular form, and total insulation; from which it is evident that
+    the Milky Way must be finally broken up and cease to be a stratum of
+    scattered stars.
+
+    "The state into which the incessant action of the clustering power
+    has brought it at present, is a kind of chronometer that may be used
+    to measure the time of its past and future existence; and although
+    we do not know the rate of going of this mysterious chronometer, it
+    is nevertheless certain that since the breaking up of the Milky Way
+    affords a proof that it cannot last forever, it equally bears
+    witness that its past duration cannot be admitted to be infinite."
+    (1814.)
+
+HERSCHEL'S relations with his cotemporaries were usually of the most
+pleasant character, though seldom intimate. This peace was broken but by
+one unpleasant occurrence. In the _Philosophical Transactions_ for 1792,
+SCHROETER had communicated a series of observations made with one of
+HERSCHEL'S own telescopes on the atmospheres of _Venus_, the Moon, etc.
+It was not only an account of phenomena which had been seen; it was
+accompanied by measures, and the computations based on these led to
+heights and dimensions for mountains on _Venus_ which were, to say the
+least, extravagant. The adjective will not seem too strong when we say
+that the very existence of the mountains themselves is to-day more than
+doubtful.
+
+The appearances seen by SCHROETER were described by him in perfectly
+good faith, and similar ones have been since recorded. His reasoning
+upon them was defective, and the measures which he made were practically
+valueless. This paper, printed in the _Transactions_ of the Royal
+Society, to which SCHROETER had not before contributed, appears to have
+irritated HERSCHEL.
+
+No doubt there were not wanting members of his own society who hinted
+that on the Continent, too, there were to be found great observers, and
+that here, at least, HERSCHEL had been anticipated even in his own
+field. I have always thought that the memoir of HERSCHEL which appeared
+in the next volume of the _Transactions_ (1793), _Observations on the
+Planet Venus_, was a rejoinder intended far more for the detractors at
+home than for the astronomer abroad. The review is conceived in a severe
+spirit. The first idea seems to be to crush an opposition which he
+feels. The truth is established, but its establishment is hardly the
+_first_ object.
+
+It seems as if HERSCHEL had almost allowed himself to be forced into a
+position of arrogance, which his whole life shows was entirely foreign
+to his nature. All through the review he does not once mention
+SCHROETER'S name. He says:
+
+    "A series of observations on _Venus_, begun by me in April, 1777,
+    has been continued down to the present time. . . . The result of my
+    observations would have been communicated long ago if I had not
+    flattered myself with the hope of some better success concerning the
+    diurnal motion of _Venus_, which has still eluded my constant
+    attention as far as concerns its period and direction. . . . Even at
+    this present time I should hesitate to give the following extracts
+    if it did not seem incumbent on me to examine by what accident I
+    came to overlook mountains in this planet of such enormous height as
+    to exceed four, five, or even six times the perpendicular height of
+    Chimboraco, the highest of our mountains. . . . The same paper contains
+    other particulars concerning _Venus_ and _Saturn_. All of which
+    being things of which I have never taken any notice, it will not be
+    amiss to show, by what follows, that neither want of attention, nor
+    a deficiency of instruments, would occasion my not perceiving these
+    mountains of more than twenty-three miles in height, this jagged
+    border of _Venus_, and these flat, spherical forms on _Saturn_."
+
+The reply of SCHROETER (1795) is temperate and just. It does him honor,
+and he generously gives full justice to his critic.
+
+It would hardly be worth while to mention this slight incident if it
+were not that during these years there certainly existed a feeling
+that HERSCHEL undervalued the labors of his cotemporaries.
+
+This impression was fostered no doubt by his general habit of not
+quoting previous authorities in the fields which he was working.
+
+A careful reading of his papers will, I think, show that his definite
+indebtedness to his _cotemporaries_ was vanishingly small. The work of
+MICHELL and WILSON he alludes to again and again, and always with
+appreciation. Certainly he seems to show a vein of annoyance that the
+papers of CHRISTIAN MAYER, _De novis in coelo sidereo phaenomenis_
+(1779), and _Beobachtungen von Fixsterntrabanten_ (1778), should have
+been quoted to prove that the method proposed by HERSCHEL in 1782 for
+ascertaining the parallax of the fixed stars by means of observations of
+those which were double, was not entirely original with himself.
+
+There is direct proof that it was so,[22] and if this was not
+forthcoming it would be unnecessary, as he has amply shown in his
+Catalogue of Double Stars. One is reminded of his remarks on the use of
+the high magnifying powers by the impatience of his comments.
+
+His proposal to call the newly discovered minor planets _asteroids_
+(1802) was received as a sign that he wished to discriminate between the
+discoveries of PIAZZI and OLBERS and his own discovery of URANUS.[23]
+
+He takes pains to quietly put this on one side in one of his papers,
+showing that he was cognizant of the existence of such a feeling.
+
+I am tempted to resurrect from a deserved obscurity a notice of
+HERSCHEL'S _Observations on the Two Lately Discovered Celestial Bodies_
+(_Philosophical Transactions_, 1802), printed in the first volume
+of the _Edinburgh Review_, simply to show the kind of envy to which even
+he, the glory of England, was subject.
+
+The reviewer sets forth the principal results of HERSCHEL'S
+observations, and, after quoting his definition of the new term
+asteroid, goes on to say:
+
+    "If a new name must be found, why not call them by some appellation
+    which shall, in some degree, be descriptive of, or at least
+    consistent with, their properties? Why not, for instance, call them
+    _Concentric Comets_, or _Planetary Comets_, or _Cometary Planets_?
+    or, if a single term must be found, why may we not coin such a
+    phrase as _Planetoid_ or _Cometoid_?"
+
+Then follows a general arraignment of HERSCHEL'S methods of expression
+and thought, as distinguished from his powers of mere observation. This
+distinction, it may be said, exists only in the reviewer's mind; there
+was no such distinction in fact. If ever a series of observations was
+directed by profound and reasonable thought, it was HERSCHEL'S own.
+
+    "Dr. HERSCHEL'S passion for coining words and idioms has often
+    struck us as a weakness wholly unworthy of him. The invention of a
+    name is but a poor achievement for him who has discovered whole
+    worlds. Why, for instance, do we hear him talking of the
+    _space-penetrating power_ of his instrument--a compound epithet and
+    metaphor which he ought to have left to the poets, who, in some
+    future age, shall acquire glory by celebrating his name. The other
+    papers of Dr. HERSCHEL, in the late volumes of the _Transactions_,
+    do not deserve such particular attention. His catalogue of 500 new
+    nebulae, though extremely valuable to the practical astronomer, leads
+    to no general conclusions of importance, and abounds with the
+    defects which are peculiar to the Doctor's writings--a great
+    prolixity and tediousness of narration--loose and often
+    unphilosophical reflections, which give no very favorable idea of
+    his scientific powers, however great his merit may be as an
+    observer--above all, that idle fondness for inventing names without
+    any manner of occasion, to which we have already alluded, and a use
+    of novel and affected idioms.
+
+       *       *       *       *       *
+
+    "To the speculations of the Doctor on the nature of the Sun, we have
+    many similar objections; but they are all eclipsed by the grand
+    absurdity which he has there committed, in his hasty and erroneous
+    theory concerning the influence of the solar spots on the price of
+    grain. Since the publication of Gulliver's voyage to Laputa, nothing
+    so ridiculous has ever been offered to the world. We heartily wish
+    the Doctor had suppressed it; or, if determined to publish it, that
+    he had detailed it in language less confident and flippant."
+
+One is almost ashamed to give space and currency to a forgotten attack,
+but it yields a kind of perspective; and it is instructive and perhaps
+useful to view HERSCHEL'S labors from all sides, even from wrong and
+envious ones.
+
+The study of the original papers, together with a knowledge of the
+circumstances in which they were written, will abundantly show that
+HERSCHEL'S ideas sprung from a profound meditation of the nature of
+things in themselves. What the origin of trains of thought prosecuted
+for years may have been we cannot say, nor could he himself have
+expressed it. A new path in science was to be found out, and he found
+it. It was not in his closet, surrounded by authorities, but under the
+open sky, that he meditated the construction of the heavens. As he says,
+"My situation permitted me not to consult large 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."
+
+His remarkable memoirs on the invisible and other rays of the solar
+spectrum were received with doubt, and with open denial by many of the
+scientific bodies of Europe. The reviews and notices of his work in this
+direction were often quite beyond the bounds of a proper scientific
+criticism; but HERSCHEL maintained a dignified silence. The discoveries
+were true, the proofs were open to all, and no response was needed from
+him. He may have been sorely tempted to reply, but I am apt to believe
+that the rumors that reached him from abroad and at home did not then
+affect him as they might have done earlier. He was at his grand
+climacteric, he had passed his sixty-third year, his temper was less
+hasty than it had been in his youth, and his nerves had not yet received
+the severe strain from whose effects he suffered during the last years
+of his life.
+
+       *       *       *       *       *
+
+We have some glimpses of his personal life in the reminiscences of him
+in the _Diary and Letters_ of Madame D'ARBLAY, who knew him well:
+
+    "1786.--In the evening Mr. HERSCHEL came to tea. I had once seen
+    that very extraordinary man at Mrs. DE LUC'S, but was happy to see
+    him again, for he has not more fame to awaken curiosity than sense
+    and modesty to gratify it. He is perfectly unassuming, yet openly
+    happy, and happy in the success of those studies which would render
+    a mind less excellently formed presumptuous and arrogant.
+
+    "The king has not a happier subject than this man, who owes it
+    wholly to His Majesty that he is not wretched; for such was his
+    eagerness to quit all other pursuits to follow astronomy solely,
+    that he was in danger of ruin, when his talents and great and
+    uncommon genius attracted the king's patronage. He has now not only
+    his pension, which gives him the felicity of devoting all his time
+    to his darling study, but he is indulged in license from the king to
+    make a telescope according to his new ideas and discoveries, that is
+    to have no cost spared in its construction, and is wholly to be paid
+    for by His Majesty.
+
+    "This seems to have made him happier even than the pension, as it
+    enables him to put in execution all his wonderful projects, from
+    which his expectations of future discoveries are so sanguine as to
+    make his present existence a state of almost perfect enjoyment.
+    Mr. LOCKE himself would be quite charmed with him.
+
+    "He seems a man without a wish that has its object in the
+    terrestrial globe. At night Mr. HERSCHEL, by the king's command,
+    came to exhibit to His Majesty and the royal family the new comet
+    lately discovered by his sister, Miss HERSCHEL; and while I was
+    playing at piquet with Mrs. SCHWELLENBURG, the Princess AUGUSTA came
+    into the room and asked her if she chose to go into the garden and
+    look at it. She declined the offer, and the princess then made it to
+    me. I was glad to accept it for all sorts of reasons. We found him
+    at his telescope. The comet was very small, and had nothing grand or
+    striking in its appearance; but it is the first lady's comet, and I
+    was very desirous to see it. Mr. HERSCHEL then showed me some of his
+    new discovered universes, with all the good humor with which he
+    would have taken the same trouble for a brother or a sister
+    astronomer; there is no possibility of admiring his genius more than
+    his gentleness."
+
+    "_1786, December 30th_.--This morning my dear father carried me to
+    Dr. HERSCHEL. That great and very extraordinary man received us
+    almost with open arms. He is very fond of my father, who is one of
+    the council of the Royal Society this year, as well as himself. . . .
+    At this time of day there was nothing to see but his instruments;
+    those, however, are curiosities sufficient. . . . I wished very much
+    to have seen his sister, . . . but she had been up all night, and
+    was then in bed."
+
+    "_1787, September_.--Dr. HERSCHEL is a delightful man; so
+    unassuming with his great knowledge, so willing to dispense it to
+    the ignorant, and so cheerful and easy in his general manners, that,
+    were he no genius, it would be impossible not to remark him as a
+    pleasing and sensible man."
+
+    "_1788, October 3d_.--We returned to Windsor at noon, and Mrs. DE
+    LUC sent me a most pressing invitation to tea and to hear a little
+    music. Two young ladies were to perform at her house in a little
+    concert. Dr. HERSCHEL was there, and accompanied them very sweetly
+    on the violin; his new-married wife was with him, and his sister.
+    His wife seems good-natured; she was rich, too! and astronomers are
+    as able as other men to discern that gold can glitter as well as
+    stars."
+
+
+                    DR. BURNEY TO MADAME D'ARBLAY.
+
+                                             "CHELSEA COLLEGE,
+
+                                                 _September 28, 1798_.
+
+    "*   *   *   *   *
+
+    "I drove through Slough in order to ask at Dr. HERSCHEL'S door when
+    my visit would be least inconvenient to him--that night or next
+    morning. The good soul was at dinner, but came to the door himself,
+    to press me to alight immediately and partake of his family repast;
+    and this he did so heartily that I could not resist.
+
+            *       *       *       *       *       *       *
+
+    "I expected (not knowing that HERSCHEL was married) only to have
+    found Miss HERSCHEL; but there was a very old lady, the mother, I
+    believe, of Mrs. HERSCHEL, who was at the head of the table herself,
+    and a Scots lady (a Miss WILSON, daughter of Dr. WILSON, of Glasgow,
+    an eminent astronomer), Miss HERSCHEL, and a little boy. They
+    rejoiced at the accident which had brought me there, and hoped I
+    would send my carriage away and take a bed with them. They were
+    sorry they had no stables for my horses.
+
+    "We soon grew acquainted--I mean the ladies and I--and before dinner
+    was over we seemed old friends just met after a long absence. Mrs.
+    HERSCHEL is sensible, good-humored, unpretending, and well bred;
+    Miss HERSCHEL all shyness and virgin modesty; the Scots lady
+    sensible and harmless; and the little boy entertaining, promising,
+    and comical. HERSCHEL, you know, and everybody knows, is one of the
+    most pleasing and well-bred natural characters of the present age,
+    as well as the greatest astronomer.
+
+    "Your health was drunk after dinner (put that into your pocket), and
+    after much social conversation and a few hearty laughs, the ladies
+    proposed to take a walk, in order, I believe, to leave HERSCHEL and
+    me together. We walked and talked round his great telescopes till it
+    grew damp and dusk, then retreated into his study to philosophize.
+
+       *       *       *       *       *
+
+    "He made a discovery to me, which, had I known it sooner, would have
+    overset me, and prevented my reading any part of my work.[24] He
+    said that he had almost always had an aversion to poetry, which he
+    regarded as the arrangement of fine words, without any useful
+    meaning or adherence to truth; but that when truth and science were
+    united to these fine words, he liked poetry very well."
+
+
+                         1798, December 10.
+
+                    DR. BURNEY TO MADAME D'ARBLAY.
+
+    "HERSCHEL has been in town for short spurts, and back again two or
+    three times, leaving Mrs. HERSCHEL behind (in town) to transact law
+    business. I had him here two whole days."
+
+    The reading of the manuscript of the _Poetical History of Astronomy_
+    was continued, "and HERSCHEL was so humble as to confess that I
+    knew more of the history of astronomy than he did, and had surprised
+    him with the mass of information I had got together.
+
+    "He thanked me for the entertainment and instruction I had given
+    him. 'Can anything be grander?' and all this before he knows a word
+    of what I have said of himself--all his discoveries, as you may
+    remember, being kept back for the twelfth and last book."
+
+
+                    DR. BURNEY TO MADAME D'ARBLAY.
+
+                             "SLOUGH, _Monday morning._ _July 22, 1799_,
+                                 in bed at Dr. HERSCHEL'S, half-past
+                                 five, where I can neither sleep nor lie
+                                 idle.
+
+    "My Dear Fanny:--I believe I told you on Friday that I was going to
+    finish the perusal of my astronomical verses to the great astronomer
+    on Saturday.
+
+       *       *       *       *       *
+
+    "After tea Dr. HERSCHEL proposed that we two should retire into a
+    quiet room in order to resume the perusal of my work, in which no
+    progress has been made since last December. The evening was
+    finished very cheerfully; and we went to our bowers not much out of
+    humor with each other or the world. . . . After dinner we all agreed
+    to go to the terrace [at Windsor]--Mr., Mrs., and Miss H., with
+    their nice little boy, and three young ladies. Here I met with
+    almost everybody I wished and expected to see previous to the
+    king's arrival.
+
+       *       *       *       *       *
+
+    "But now here comes Will, and I must get up, and make myself up to
+    go down to the perusal of my last book, entitled _Herschel_. So
+    good-morrow."
+
+
+                                                "CHELSEA, _Tuesday._
+
+    "Not a moment could I get to write till now. . . . I must tell you
+    that HERSCHEL proposed to me to go with him to the king's concert at
+    night, he having permission to go when he chooses, his five nephews
+    (GRIESBACHS) making a principal part of the band. 'And,' says he,
+    'I know you will be welcome.'"
+
+An intimacy was gradually established between HERSCHEL and Dr. BURNEY.
+They saw each other often at the meetings of the Royal Society, and
+HERSCHEL frequently stayed at the doctor's house. "On the first evening
+HERSCHEL spent at Chelsea, when I called for my ARGAND lamp, HERSCHEL,
+who had not seen one of those lamps, was surprised at the great effusion
+of light, and immediately calculated the difference between that and a
+single candle, and found it sixteen to one."[25]
+
+In 1793 we find HERSCHEL as a witness for his friend JAMES WATT, in the
+celebrated case of WATT _vs._ BULL, which was tried in the Court of
+Common Pleas. And from MUIRHEAD'S Life of WATT, it appears that HERSCHEL
+visited WATT at Heathfield in 1810.
+
+A delightful picture of the old age of HERSCHEL is given by the poet
+CAMPBELL,[26] whose nature was fitted to perceive the beauties of a
+grand and simple character like HERSCHEL'S:
+
+
+                                      "[BRIGHTON], _September 15, 1813_.
+
+    . . . "I wish you had been with me the day before yesterday, when you
+    would have joined me, I am sure, deeply in admiring a great, simple,
+    good old man--Dr. HERSCHEL. Do not think me vain, or at least put up
+    with my vanity, in saying that I almost flatter myself I have made
+    him my friend. I have got an invitation, and a pressing one, to go
+    to his house; and the lady who introduced me to him, says he spoke
+    of me as if he would really be happy to see me. . . . I spent all
+    Sunday with him and his family. His son is a prodigy in sciences,
+    and fond of poetry, but very unassuming. . . . Now, for the old
+    astronomer himself. His simplicity, his kindness, his anecdotes, his
+    readiness to explain--and make perfectly conspicuous too--his own
+    sublime conceptions of the universe are indescribably charming. He
+    is seventy-six, but fresh and stout; and there he sat, nearest the
+    door, at his friend's house, alternately smiling at a joke, or
+    contentedly sitting without share or notice in the conversation.
+    Any train of conversation he follows implicitly; anything you ask he
+    labors with a sort of boyish earnestness to explain.
+
+    "I was anxious to get from him as many particulars as I could about
+    his interview with BUONAPARTE.[27] The latter, it was reported, had
+    astonished him by his astronomical knowledge.
+
+    "'No,' he said, 'the First Consul did surprise me by his quickness
+    and versatility on all subjects; but in science he seemed to know
+    little more than any well-educated gentleman, and of astronomy much
+    less for instance than our own king. His general air,' he said, 'was
+    something like affecting to know more than he did know.' He was
+    high, and tried to be great with HERSCHEL, I suppose, without
+    success; and 'I remarked,' said the astronomer, 'his hypocrisy in
+    concluding the conversation on astronomy by observing how all these
+    glorious views gave proofs of an Almighty Wisdom.' I asked him if he
+    thought the system of LAPLACE to be quite certain, with regard to
+    the total security of the planetary system from the effects of
+    gravitation losing its present balance? He said, No; he thought by
+    no means that the universe was secured from the chance of sudden
+    losses of parts.
+
+    "He was convinced that there had existed a planet between _Mars_
+    and _Jupiter_, in our own system, of which the little asteroids, or
+    planetkins, lately discovered, are indubitably fragments; and
+    'Remember,' said he, 'that though they have discovered only four of
+    those parts, there will be thousands--perhaps thirty thousand
+    more--yet discovered.' This planet he believed to have been lost by
+    explosion.
+
+    "With great kindness and patience he referred me, in the course of
+    my attempts to talk with him, to a theorem in NEWTON'S 'Principles
+    of Natural Philosophy' in which the time that the light takes to
+    travel from the sun is proved with a simplicity which requires but a
+    few steps in reasoning. In talking of some inconceivably distant
+    bodies, he introduced the mention of this plain theorem, to remind
+    me that the progress of light could be measured in the one case as
+    well as the other. Then, speaking of himself, he said, with a
+    modesty of manner which quite overcame me, when taken together with
+    the greatness of the assertion: 'I have looked _further into space
+    than ever human being did before me_. I have observed stars, of
+    which the light, it can be proved, must take two millions of years
+    to reach this earth.'
+
+    "I really and unfeignedly felt at this moment as if I had been
+    conversing with a supernatural intelligence. 'Nay, more,' said he,
+    'if those distant bodies had ceased to exist two millions of years
+    ago, we should still see them, as the light would travel after the
+    body was gone. . . .' These were HERSCHEL'S words; and if you had
+    heard him speak them, you would not think he was apt to tell more
+    than the truth.
+
+    "After leaving HERSCHEL I felt elevated and overcome; and have in
+    writing to you made only this memorandum of some of the most
+    interesting moments of my life."
+
+CAMPBELL'S conscientious biographer appears to have felt that the value
+of this charming account of his interview with HERSCHEL was in its
+report of astronomical facts and opinions, and he adds a foot-note to
+explain that "HERSCHEL'S opinion never amounted to more than
+_hypothesis_ having some degree of probability. Sir JOHN HERSCHEL
+remembers his father saying, 'If that hypothesis were true, and _if_ the
+planet destroyed were as large as the earth, there must have been at
+least thirty-thousand such fragments,' but always as an hypothesis--he
+was never heard to declare any degree of conviction that it was so."
+
+For us, the value of this sympathetic account of a day in HERSCHEL'S
+life is in its conception of the simplicity, the modesty, the "boyish
+earnestness," the elevation of thought and speech of the old
+philosopher; and in the impression made on the feelings, not the mind,
+of the poet, then thirty-five years old.
+
+In a letter to ALISON, CAMPBELL reverts with great pleasure to the day
+spent with HERSCHEL:
+
+                                         "SYDENHAM, _December 12, 1813_.
+
+"MY DEAREST ALISON:--
+
+       *       *       *       *       *
+
+    "I spent three weeks with my family at Brighton, in charming
+    weather, and was much pleased with, as well as benefited by, the
+    place. There I met a man with whom you will stare at the idea of my
+    being congenial, or having the vanity to think myself so--the great
+    HERSCHEL. He is a simple, great being. . . . I once in my life
+    looked at NEWTON'S _Principia_, and attended an astronomical class
+    at Glasgow; wonderful it seemed to myself, that the great man
+    condescended to understand my questions; to become apparently
+    earnest in communicating to me as much information as my limited
+    capacity and preparation for such knowledge would admit. He invited
+    me to see him at his own abode, and so kindly that I could not
+    believe that it was mere good breeding; but a sincere wish to see me
+    again. I had a full day with him; he described to me his whole
+    interview with BUONAPARTE; said it was not true, as reported, that
+    BUONAPARTE understood astronomical subjects deeply, but affected
+    more than he knew.
+
+    "In speaking of his great and chief telescope, he said with an air,
+    not of the least pride, but with a greatness and simplicity of
+    expression that struck me with wonder, 'I have looked further into
+    space than ever human being did before me. I have observed stars, of
+    which the light takes _two millions_ of years to travel to this
+    globe.' I mean to pay him a reverential visit at Slough, as soon as
+    my book is out, this winter."
+
+       *       *       *       *       *
+
+In 1807 CAROLINA HERSCHEL has this entry in her diary:
+
+    "_October_ 4.--My brother came from Brighton. The same night two
+    parties from the Castle came to see the comet, and during the whole
+    month my brother had not an evening to himself. As he was then in
+    the midst of polishing the forty-foot mirror, rest became absolutely
+    necessary after a day spent in that most laborious work; and it has
+    ever been my opinion that on the 14th of October his nerves received
+    a shock of which he never got the better afterwards."
+
+In the spring of 1808 he was quite seriously ill; but in May the
+observing went on again. In 1809 and 1810 his principal investigations
+were upon physical subjects (NEWTON'S rings), and in 1811 the only long
+series of observations was upon the comet of that year. After 1811 the
+state of HERSCHEL'S health required that his observations should be
+much less frequent. Much of the time after 1811 he was absent, and his
+work at home consisted largely in arranging the results of his previous
+labors, and in computations connected with them. All through the years
+1814 to 1822, HERSCHEL'S health was very feeble. The severe winter of
+1813-14 had told materially upon him. In 1814, however, he undertook to
+repolish the forty-foot mirror, but was obliged to give it over.
+
+He now found it necessary to make frequent little excursions for change
+of air and scene. His faithful sister remained at home, bringing order
+into the masses of manuscript, and copying the papers for the Royal
+Society.
+
+She was sick at heart, fearing that each time she saw her brother it
+would be the last. In 1818 she says:
+
+    "Feb. 11, I went to my brother and remained with him till the 23d.
+    We spent our time, though not in idleness, in sorrow and sadness.
+    He is not only unwell, but low in spirits."
+
+In 1818 (December 16), HERSCHEL went to London to have his portrait
+painted by ARTAUD. While he was in London his will was made.[28]
+
+In 1819 there is a glimmer of the old-time light. In a note HERSCHEL
+says:
+
+    "LINA:--There is a great comet. I want you to assist me. Come to
+    dine and spend the day here. If you can come soon after one o'clock,
+    we shall have time to prepare maps and telescopes. I saw its
+    situation last night. It has a long tail.
+
+    "_July 4, 1819._"
+
+This note has been carefully kept by his sister, and on it she has
+written: "I keep this as a relic. Every line _now_ traced by the hand of
+my dear brother becomes a treasure to me."
+
+So the next three years passed away. Sir WILLIAM[29] was daily more and
+more feeble. He spent his time in putting his works in order, but could
+devote only a few moments each day to this. His sister says:
+
+    "_Aug. 11th_, _12th_, _13th_, and _14th_ [1822], I went as usual to
+    spend some hours of the forenoon with my brother.
+
+    "_Aug. 15th._--I hastened to the spot where I was wont to find him,
+    with the newspaper which I was to read to him. But instead I found
+    Mrs. MONSON, Miss BALDWIN, and Mr. BULMAN, from Leeds, the grandson
+    of my brother's earliest acquaintance in this country. I was
+    informed my brother had been obliged to return to his room, whither
+    I flew immediately. Lady H. and the housekeeper were with him,
+    administering everything which could be thought of for supporting
+    him. I found him much irritated at not being able to grant Mr.
+    BULMAN'S request for some token of remembrance for his father. As
+    soon as he saw me, I was sent to the library to fetch one of his
+    last papers and a plate of the forty-foot telescope. But for the
+    universe I could not have looked twice at what I had snatched from
+    the shelf, and when he faintly asked if the breaking up of the Milky
+    Way was in it, I said 'Yes,' and he looked content. I cannot help
+    remembering this circumstance; it was the last time I was sent to
+    the library on such an occasion. That the anxious care for his
+    papers and workrooms never ended but with his life, was proved by
+    his frequent whispered inquiries if they were locked and the key
+    safe, of which I took care to assure him that they were, and the key
+    in Lady HERSCHEL'S hands.
+
+    "After half an hour's vain attempt to support himself, my brother
+    was obliged to consent to be put to bed, leaving no hope ever to see
+    him rise again."
+
+On the 25th of August, 1822, HERSCHEL died peacefully at the age of
+eighty-four years.
+
+His remains lie in the little church at Upton, near Windsor, where a
+memorial tablet has been erected by his son. The epitaph is as
+follows:[30]
+
+                             H. S. E.
+
+                GULIELMUS HERSCHEL Eques Guelphicus
+               Hanoviae natus Angliam elegit patriam
+               Astronomis aetatis suae praestantissimis
+                       Merito annumeratus
+                  Ut leviora sileantur inventa
+               Planetam ille extra Saturni orbitam
+                          Primus detexit
+                  Novis artis adjumentis innixus
+                 Quae ipse excogitavit et perfecit
+                   Coelorum perrupit claustra
+            Et remotiora penetrans et explorans spatia
+                    Incognitos astrorum ignes
+            Astronomorum oculis et intellectui subjecit
+                    Qua sedulitate qua solertia
+                      Corporum et phantasmatum
+             Extra systematis nostri fines lucentium
+                       Naturam indagaverit
+                Quidquid paulo audacius conjecit
+                  Ingenita temperans verecundia
+                  Ultro testantur hodie aequales
+                  Vera esse quae docuit pleraque
+           Siquidem certiora futuris ingeniis subsidia
+                     Debitura est astronomia
+                     Agnoscent forte posteri
+                 Vitam utilem innocuam amabilem
+         Non minus felici laborum exitu quam virtutibus
+                     Ornatam et vere eximiam
+               Morte suis et bonis omnibus deflenda
+                    Nec tamen immatura clausit
+                Die XXV Augusti A. D. CI[C]I[C]CCCXXII
+                      AEtatis vero suae LXXXIV.
+
+FOOTNOTES:
+
+[18] BODE'S _Jahrbuch_, 1788, p. 144.
+
+[19] ZACH'S _Monatlich Correspondenz_, 1802, p. 56.
+
+[20] BODE'S _Jahrbuch_, 1788, p. 161.
+
+[21] Through Sir JOHN HERSCHEL there is preserved to us an
+incident of his early boyhood, which shows the nature of the training
+his young mind received in the household at Slough.
+
+Walking with his father, he asked him "What was the oldest of all
+things?" The father replied, after the Socratic manner, "And what do you
+suppose is the oldest of all things?" The boy was not successful in his
+answers, whereon the old astronomer took up a small stone from the
+garden walk: "There, my child, there is the oldest of all the things
+that I certainly know." On another occasion the father asked his son,
+"What sort of things do you think are most alike?" The boy replied,
+"The leaves of the same tree are most like each other." "Gather, then,
+a handful of leaves from that tree," rejoined the philosopher,
+"and choose two which are alike."--_Monthly Notices Royal Astronomical
+Society_, vol. xxxii., page 123.
+
+[22] _Memoir of CAROLINE HERSCHEL_, p. 42.
+
+[23] "Of late years these expectations have been more than
+accomplished by the discovery of no fewer than four planetary bodies,
+almost all in the same place; but so small that Dr. HERSCHEL refuses to
+honor them with the name of planets, and chooses to call them asteroids,
+though for what reason it is not easy to determine, unless it be to
+deprive the discoverers of these bodies of any pretence for rating
+themselves as high in the list of astronomical discoverers as
+himself."--_History of the Royal Society_, by THOMAS THOMSON, p. 358.
+This work was published in 1812, and therefore during the lifetime of
+HERSCHEL.
+
+[24] _Poetical History of Astronomy_: this work was nearly
+completed, but was never published. The whole of it was read to
+HERSCHEL, in order that BURNEY might have the benefit of his criticism
+on its technical terms.
+
+[25] _Memoirs of Dr. BURNEY_, vol. iii., p. 264.
+
+[26] Life and Letters of THOMAS CAMPBELL, edited by WILLIAM
+BEATTIE, vol. ii., p. 234.
+
+[27] This interview must have taken place in 1802, during
+HERSCHEL'S journey to Paris. We have no other record of it.
+
+[28] The will of HERSCHEL was dated December 17th, 1818.
+
+"The personal effects were sworn under L6,000. The copyhold and other
+lands and tenements at Upton-cum-Chalvey, in the County of Bucks, and at
+Slough, he decrees to his son, with L25,000 in the 3 per cent. Reduced
+Annuities. L2,000 are given to his brother JOHANN DIETRICH, and
+annuities of L100 each to his brother JOHANN ALEXANDER and to his sister
+CAROLINA; L20 each to his nephews and nieces, and the residue (with the
+exception of astronomical instruments, telescopes, observations, etc.,
+which he declares to have given, on account of his advanced age, to his
+son for the purpose of continuing his studies) is left solely to Lady
+HERSCHEL."--_Gentleman's Magazine_, vol. xcii., 1822, p. 650.
+
+It is not necessary to say here how nobly Sir JOHN HERSCHEL redeemed the
+trust confided in him. All the world knows of his Survey of the Southern
+Heavens, in which he completed the review of the sky which had been
+begun and completed for the northern heavens by the same instruments in
+his father's hands. A glance at the Bibliography at the end of this book
+will show the titles of several papers by Sir JOHN, written with the
+sole object of rendering his father's labors more complete.
+
+[29] He was created a knight of the Royal Hanoverian
+Guelphic Order in 1816, and was the first President of the Royal
+Astronomical Society in 1821, his son being its first Foreign
+Secretary.
+
+[30] BODE'S _Jahrbuch_, 1823, p. 222.
+
+
+
+
+                               CHAPTER IV.
+
+          REVIEW OF THE SCIENTIFIC LABORS OF WILLIAM HERSCHEL.
+
+
+In this chapter I shall endeavor to give such explanations as will
+enable the general reader to follow the course of discovery in each
+branch of astronomy and physics, regularly through the period of
+HERSCHEL'S life, and up to the state in which he left it.
+
+A more detailed and precise account, which should appeal directly to the
+professional astronomer, will not be needed, since ARAGO has already
+fulfilled this want in his "_Analyse de la vie et des travaux de Sir
+WILLIAM HERSCHEL_," published in 1842. The few misconceptions there
+contained will be easily corrected by those to whom alone they are of
+consequence. The latter class of readers may also consult the abstracts
+of HERSCHEL'S memoirs, which have been given in "_A Subject-index and a
+Synopsis of the Scientific Writings of Sir WILLIAM HERSCHEL_," prepared
+by Dr. HASTINGS and myself, and published by the Smithsonian
+Institution.
+
+An accurate sketch of the state of astronomy in England and on the
+Continent, in the years 1780-1820, need not be given. It will be enough
+if we remember that of the chief observatories of Europe, public and
+private, no one was actively devoted to such labors as were undertaken
+by HERSCHEL at the very beginning of his career.
+
+His observations on variable stars, indeed, were in the same line as
+those of PIGOTT; FLAUGERGUES and DARQUIER, in France, had perhaps
+preceded him in minute scrutiny of the sun's surface, etc.; but, even in
+that department of observation, he at once put an immense distance
+between himself and others by the rapid and extraordinary advances in
+the size and in the excellence of his telescopes. Before his time the
+principal aids to observation were the Gregorian and Newtonian
+telescopes of SHORT, and the small achromatics of DOLLOND.[31]
+
+We have seen, in what goes before, how his patient zeal had succeeded in
+improving upon these. There was no delay, and no rest. Steadily the art
+of making reflectors was urged forward, until he had finally in his
+hands the forty-foot telescope.
+
+It must be admitted that this was the limit to which the manufacture of
+powerful telescopes could be pushed in his generation. The optical and
+mechanical difficulties which prevented a farther advance required time
+for their solution; and, indeed, some of these difficulties are scarcely
+solved at this day. It may fairly be said that no reflector larger than
+three feet in aperture has yet realized our expectations.
+
+
+           _The Improvement of Telescopes and Optical Apparatus._
+
+It will be of interest to give in this place some connected account of
+the large forty-foot reflector, of four feet aperture, made by HERSCHEL.
+Its history extends from 1785 to 1811. Its manufacture was considered by
+his cotemporaries as his greatest triumph. As a machine, it was
+extremely ingenious in all its parts, as may be seen from the elaborate
+description and plates of it published in the _Philosophical
+Transactions_ for 1795. One of its mirrors certainly had good
+definition, for, by means of it, the two small satellites of _Saturn_
+(_Mimas_ and _Enceladus_) were discovered, and these discoveries alone
+would make it famous. Perhaps more was expected of it by the public in
+general than it absolutely performed. Its merits were after a while
+decried, and HERSCHEL even felt obliged to state why he did not always
+employ it in his observations. His reasons were perfectly valid, and
+such as any one may understand. The time required to get so large a
+machine into working order was a serious tax; it required more
+assistants than his twenty-foot telescope, and he says, "I have made it
+a rule never to employ a larger telescope when a smaller will answer the
+purpose."
+
+It still remains as a remarkable feat of engineering and an example of
+great optical and mechanical skill. It led the way to the large
+reflectors of Lord ROSSE, some sixty years later, and several of the
+forty-foot telescopes of the present day even have done less useful
+work. Its great feat, however, was to have added two satellites to the
+solar system. From the published accounts of it the following is taken:
+
+    "When I resided at Bath I had long been acquainted with the theory
+    of optics and mechanics, and wanted only that experience so
+    necessary in the practical part of these sciences. This I acquired
+    by degrees at that place, where in my leisure hours, by way of
+    amusement, I made several two-foot, five-foot, seven-foot, ten-foot,
+    and twenty-foot Newtonian telescopes, beside others, of the
+    Gregorian form, of eight, twelve, and eighteen inches, and two,
+    three, five, and ten feet focal length. In this way I made not less
+    than two hundred seven-foot, one hundred and fifty ten-foot, and
+    about eighty twenty-foot mirrors, not to mention the Gregorian
+    telescopes.[32]
+
+    "The number of stands I invented for these telescopes it would not
+    be easy to assign. . . . In 1781 I began to construct a thirty-foot
+    aerial reflector, and having made a stand for it, I cast the mirror
+    thirty-six inches in diameter. This was cracked in cooling. I cast
+    it a second time, and the furnace I had built in my house broke."
+
+Soon after, the Georgian planet was discovered, and this interrupted the
+work for a time.
+
+    "In the year 1783 I finished a very good twenty-foot reflector with
+    a large aperture, and mounted it upon the plan of my present
+    telescope. After two years' observation with it, the great advantage
+    of such apertures appeared so clearly to me that I recurred to my
+    former intention of increasing them still further; and being now
+    sufficiently provided with experience in the work which I wished to
+    undertake, the President of the Royal Society, who is always ready
+    to promote useful undertakings, had the goodness to lay my design
+    before the king. His Majesty was graciously pleased to approve of
+    it, and with his usual liberality to support it with his royal
+    bounty.
+
+    "In consequence of this arrangement I began to construct the
+    forty-foot telescope about the latter end of 1785.[33] The woodwork
+    of the stand and machines for giving the required motions to the
+    instrument were immediately put in hand. In the whole of the
+    apparatus none but common workmen were employed, for I made drawings
+    of every part of it, by which it was easy to execute the work, as I
+    constantly inspected and directed every person's labor; though
+    sometimes there were not less than forty different workmen employed
+    at the same time. While the stand of the telescope was preparing, I
+    also began the construction of the great mirror, of which I
+    inspected the casting, grinding, and polishing, and the work was in
+    this manner carried on with no other interruption than that
+    occasioned by the removal of all the apparatus and materials from
+    where I then lived, to my present situation at Slough.
+
+    "Here, soon after my arrival, I began to lay the foundation upon
+    which by degrees the whole structure was raised as it now stands,
+    and the speculum being highly polished and put into the tube, I had
+    the first view through it on February 19, 1787. I do not, however,
+    date the completing of the instrument till much later. For the first
+    speculum, by a mismanagement of the person who cast it, came out
+    thinner on the centre of the back than was intended, and on account
+    of its weakness would not permit a good figure to be given to it.
+
+    "A second mirror was cast January 26, 1788, but it cracked in
+    cooling. February 16 we recast it, and it proved to be of a proper
+    degree of strength. October 24 it was brought to a pretty good
+    figure and polish, and I observed the planet _Saturn_ with it. But
+    not being satisfied, I continued to work upon it till August 27,
+    1789, when it was tried upon the fixed stars, and I found it to give
+    a pretty sharp image. Large stars were a little affected with
+    scattered light, owing to many remaining scratches on the mirror.
+    August the 28th, 1789, having brought the telescope to the parallel
+    of _Saturn_, I discovered a _sixth_ satellite of that planet, and
+    also saw the spots upon _Saturn_ better than I had ever seen them
+    before, so that I may date the finishing of the forty-foot telescope
+    from that time."
+
+Another satellite of _Saturn_ was discovered with the forty-foot on the
+17th of September (1789). It was used for various observations so late
+as 1811. On January 19, of that year, HERSCHEL observed the nebula of
+_Orion_ with it. This was one of his last observations.
+
+The final disposition of the telescope is told in the following extract
+from a letter of Sir JOHN HERSCHEL'S to Mr. WELD, Secretary of the Royal
+Society:
+
+                                       "COLLINGWOOD, _March 13, 1847_.
+
+    . . . "In reply to your queries, respecting the forty-foot
+    reflecting telescope constructed by my father, I have to state that
+    King GEORGE III. munificently defrayed the _entire_ cost of that
+    instrument (including, of course, all preparatory cost in the nature
+    of construction of tools, and of the apparatus for casting, grinding,
+    and figuring the reflectors, of which two were constructed), at a
+    total cost of L4,000. The woodwork of the telescope being so far
+    decayed as to be dangerous, in the year 1839 I pulled it down, and
+    piers were erected on which the tube was placed, _that_ being of
+    iron and so well preserved, that, although not more than
+    one-twentieth of an inch thick, when in the horizontal position it
+    sustained within it all my family, and continues to sustain inclosed
+    within it, to this day, not only the heavier of the two reflectors,
+    but also all the more important portions of the machinery. . . .
+    The mirror and the rest of the polishing apparatus are on the
+    premises. The iron grinding tools and polishers are placed
+    underneath the tube, let into the ground, and level with the surface
+    of the gravelled area in which it stands.". . .
+
+The closing of the tube was done with appropriate ceremony on
+New-Year's-Day, 1840, when, after a procession through it by the family
+at Slough, a poem, written by Sir JOHN, was read, the machinery put into
+its present position, and the tube sealed.
+
+The memoir on the forty-foot telescope shows throughout that HERSCHEL'S
+prime object was not the making of the telescope itself, but that his
+mind was constantly directed towards the uses to which it was to be
+put--towards the questions which he wished it to answer.
+
+Again and again, in his various papers, he returns to the question of
+the _limit of vision_. As BESSEL has said:
+
+    "The naked eye has its limit of vision in the stars of the sixth
+    magnitude. The light of fainter stars than these does not affect the
+    retina enough for them to be seen. A very small telescope penetrates
+    to smaller, and, in general, without doubt, to more distant stars.
+    A more powerful one penetrates deeper into space, and as its power is
+    increased, so the boundaries of the visible universe are widened,
+    and the number of stars increased to millions and millions. Whoever
+    has followed the history of the series of HERSCHEL'S telescopes will
+    have observed this. But HERSCHEL was not content with the bare fact,
+    but strove ever to know _how far_ a telescope of a certain
+    construction and size could penetrate, compared with the naked and
+    unassisted eye. These investigations were never for the discovery of
+    new facts concerning the working of his instruments; it was for the
+    knowledge of the distribution of the fixed stars in space itself
+    that he strove. . . . HERSCHEL'S instruments were designed to aid
+    vision to the last extent. They were only secondarily for the taking
+    of measures. His efforts were not for a knowledge of the _motions_,
+    but of the _constitution_ and _construction_ of the heavenly
+    bodies."
+
+Besides the stands for his telescopes, which were both ingenious and
+convenient, HERSCHEL devised many forms of apparatus for facilitating
+the art of observation. His micrometers for measuring position angles,
+his lamp micrometer, the method of limiting apertures, and the methods
+he used for viewing the sun may be mentioned among these.
+
+Points in practical astronomy are considered all through the years of
+observation. A reference to his original papers will show how numerous,
+how varied, and how valuable these are. I cannot forbear quoting here
+the account of a precaution observed during his examination of the belts
+on _Saturn_ (1794).
+
+It is the most striking example of how fully HERSCHEL realized that the
+eye of the observer is a material part of the optical apparatus of
+astronomy. Simple as this principle may appear, it was an absolute
+novelty in his day.
+
+In making these observations, he says:
+
+    "I took care to bend my head so as to receive the picture of the
+    belt in the same direction as I did formerly. This was a precaution
+    that occurred to me, as there was a possibility that the vertical
+    diameter of the retina might be more or less sensitive than the
+    horizontal one."
+
+Astronomers will recognize in this the first suggestion of the processes
+which have led to important results in the hands of Dr. OTTO STRUVE and
+others in the comparison of the measures of double stars by different
+observers, each of whom has a personal habit of observation, which, if
+not corrected, may affect his results in the way which HERSCHEL was
+striving to avoid.
+
+
+           _Researches on the Relative Brightness of the
+                     Stars: Variable Stars._
+
+No research of HERSCHEL'S was more laborious than the elaborate
+classification of the stars according to their comparative brightness,
+which he executed during the years 1796 to 1799. It was directly in the
+line of his main work--to find out the construction of the heavens.
+
+His first paper had been upon the variable star _Mira Ceti_. Here was a
+sun, shining by its native brightness, which waxed and waned like the
+moon itself. This star is periodic. It is for a long period invisible to
+the unassisted eye. Then it can just be seen, and increases in
+brightness for a little over a month, and attains a maximum brilliancy.
+From this it decreases for nearly three months, and after becoming
+invisible, remains so for five or six months. Its whole period is about
+333 days. Are all other stars constant in brightness? The example of
+_Mira Ceti_ and of other known variables makes this at least doubtful.
+But the sun itself may vary for all that we know. It is a simple star
+like the rest.
+
+This question of variability in general is an important one, then.
+It can only be tested by making accurate catalogues of the relative
+brilliance of stars at various times, and by comparing these. No such
+general catalogue existed before HERSCHEL'S time, and led by the
+discrepancies in isolated cases, which he found between his own
+estimates and those of his predecessors, he made from observation a
+series of four catalogues, in which were set down the order of sequence
+of the stars of each constellation.
+
+The method adopted by HERSCHEL was perfectly simple in principle, though
+most laborious in practice. Suppose any number of stars, A, B, C, D, E,
+. . . etc., near enough to each other to be well compared. The process
+consists simply in writing down the names of the stars, A, B, C, etc.,
+in the order of their relative brightness. Thus if for a group of eight
+stars we have found at one epoch A, B, C, D, E, F, G, H, and if at
+another time the order was A, B, C, D, F, E, G, H, symptoms of
+variability are pointed out. Repeated observations, where the same star
+is found in different sequences, will decide the question. Thus, for the
+stars visible to the naked eye, we know exactly the state of the sky in
+HERSCHEL'S day, now nearly a century ago. Any material change cannot
+escape us. These catalogues have been singularly overlooked by the
+observers of our generation who have followed this branch of
+observation, and it was not till 1876 that they received proper
+attention and a suitable reduction (at the hands of Mr. C. S. PIERCE).
+
+We owe to HERSCHEL the first trustworthy account of the stars visible
+to the naked eye, and since the date of his labors (about 1800) we have
+similar views published by ARGELANDER (1839), HEIS (1848), ARGELANDER
+and SCHOeNFELD (1857), GOULD (1860 and 1872), and HOUZEAU (1875). Thus
+his labors have been well followed up.
+
+In the prosecution of this work HERSCHEL found stars whose light was
+progressively diminishing, others which regularly increased, one star
+whose light periodically varies (_[alpha] Herculis_), and at least
+one star (55 _Herculis_) which has utterly disappeared. On October 10,
+1781, and April 11, 1782, he observed this latter star, but in May,
+1791, it had totally vanished. There was no trace remaining.
+
+The discovery of the variability of _[alpha] Herculis_ was a more
+important one than would at first sight appear. Up to that time the only
+variable stars known were seven in number. Their periods were four
+hundred and ninety-four, four hundred and four, three hundred and
+thirty-four, seven, six, five, and three days. These periods seemed to
+fall into two groups, one of from three hundred to five hundred days,
+the other comparatively much shorter, of three to seven days.
+_[alpha] Herculis_ came to occupy the middle place between these groups,
+its period being about sixty days.
+
+The cause of these strange and regular variations of brightness was
+supposed by HERSCHEL to be the rotation of the star bodily on an axis,
+by which revolution different parts of its surface, of different
+brilliancy, were successively and periodically presented to us. This
+explanation it might have been difficult to receive, when the periods of
+the known variables were so markedly various in length. His own
+discovery came to bridge over the interval, and quite confirmed him in
+his belief. He returned to the subject of the revolution of stars about
+their axes again and again, and connected it with the revolution of
+satellites.
+
+He found that the satellites of _Jupiter_ and one of _Saturn's_
+periodically changed in brightness, and by quite simple means showed
+that their periods of rotation were at least approximately the same as
+their periods of revolution about their primaries. In this case, as in
+every other, he considered a discovery in each and every one of its
+possible bearings. There are no instances where he has singularly
+overlooked the consequences of his observations.
+
+
+                    _Researches on Double Stars._
+
+The double stars were the subject of HERSCHEL'S earliest and of his
+latest papers. In 1782 he published his "_Catalogue of Double Stars_,"
+and his last published memoir (1822) was on the same subject.
+
+The question of determining the parallax of stars first brought HERSCHEL
+to the discovery of double stars. If two stars, A and B, appear very
+close together, and if, in reality, the star B is very many times more
+distant from the earth than A, although seen along the same line of
+sight, then the revolution of the earth in its orbit will produce
+changes in the relative situation of A and B, and, in fact, B will
+describe a small orbit about A, due to this revolution. This idea had
+been proposed by GALILEO, and measures on this plan had been made by
+LONG, with negative results. But HERSCHEL, in reviewing their work,
+declares that the stars chosen by LONG were not suitable to the purpose.
+It is necessary, among other things, to the success of this method, that
+it should be certain that the star B is really very much more distant
+than the star A. The only general test of the distance of stars is their
+brilliancy, and HERSCHEL decided to use only stars for this research
+which had two components very greatly different in brightness. A must be
+very bright (and presumably near to us), and B must be very close to A,
+and very faint (and thus, presumably, very distant).
+
+It was in the search for such pairs of stars that the _Catalogue of
+Double Stars_ (1782) was formed. HERSCHEL'S first idea of a double star
+made such pairs as he found, to consist of two stars _accidentally_ near
+to each other. A was near to us, and appeared projected in a certain
+place on the celestial sphere. B was many times more distant, but, by
+chance, was seen along the same line, and made with A an _optical_
+double. If the two stars were at the same distance from the earth, if
+they made part of the same physical system, if one revolved around the
+other, then this method of gaining a knowledge of their distance failed.
+Even in his first memoir on the subject, a surmise that this latter
+state might occur in some cases, was expressed by HERSCHEL. The notes on
+some of the pairs declare that a motion of one of them was suspected.
+But this motion might be truly orbital--of one star about the other as
+a centre--or it might simply be that one star was moving by its own
+_proper_ motion, and leaving the other behind. It was best to wait and
+see. The first Catalogue of Double Stars contained two hundred and three
+instances of such associations. These were observed from time to time,
+and new pairs discovered. The paper of MICHELL, "An Inquiry into the
+probable Parallax and Magnitude of the Fixed Stars, from the Quantity of
+Light which they Afford, and the Particular Circumstances of their
+Situation" (1767), was read and pondered. By 1802 HERSCHEL had become
+certain that there existed in the heavens real pairs of stars, both at
+the same distance from the earth, which were physically connected with
+each other. The arguments of MICHELL have been applied by BESSEL to the
+case of one of HERSCHEL'S double stars, in much the same order in which
+the argument ran in HERSCHEL'S own mind, as follows:
+
+The star _Castor_ (_[alpha] Geminorum_) is a double star, where A is of
+the second, and B of the fourth, magnitude. To the naked eye these two
+appear as one star. With a telescope this is seen to be two stars, some
+5" apart. In the whole sky there are not above fifty such stars
+as the brighter of the two, and about four hundred of the brilliancy of
+B. These fifty and four hundred stars are scattered over the vault of
+heaven, almost at random. No law has yet been traced by which we can say
+that here or here there shall be a bright star like A, or a fainter one
+like B. In general the distribution appears to be fortuitous. How then
+can we account for one of the four hundred stars like B placed so close
+to one of the fifty like A?
+
+The chances are over four hundred thousand to one that the association
+in position is not accidental. This argument becomes overwhelming when
+the same association is found in many other cases. There were two
+hundred and three doubles in the Catalogue of 1782 alone, and many
+thousands are now known.
+
+By a process like this, HERSCHEL reached his grand discovery of true
+binary systems, where one sun revolves about another. For he saw that
+if the two stars are near together in space, they could not stand still
+in face of each other, but that they must revolve in true orbits. Here
+was the discovery which came to take the place of the detection of the
+parallaxes of the fixed stars.
+
+He had failed in one research, but he was led to grand conclusions.
+Was the force that these distant pairs of suns obeyed, the force of
+gravitation? This he could not settle, but his successors have done so.
+It was not till about 1827 that SAVARY, of the Paris Observatory, showed
+that one of HERSCHEL'S doubles was subjected to the law of gravitation,
+and thus extended the power of this law from our system to the universe
+at large. HERSCHEL himself lived to see some of his double stars perform
+half a revolution.
+
+Of HERSCHEL'S discoveries, ARAGO thinks this has "le plus d'avenir."
+It may well be so. The laws which govern our solar system have been
+extended, through his researches, to regions of unknown distance. The
+binary stars will afford the largest field for research into the laws
+which govern them, and together with the clusters and groups, they will
+give a firm basis by which to study the distribution of stars in
+general, since here we have the great advantage of knowing, if not the
+real distance of the two stars from the earth, at least that this
+distance is alike for both.
+
+
+                  _Researches on Planets and Satellites._
+
+After HERSCHEL'S first publication on the mountains of the Moon (1780),
+our satellite appears to have occupied him but little. The observation
+of volcanoes (1787) and of a lunar eclipse are his only published ones.
+The planets _Mercury_, _Venus_, _Mars_, and _Jupiter_, although they
+were often studied, were not the subjects of his more important memoirs.
+The planet _Saturn_, on the contrary, seems never to have been lost
+sight of from the time of his first view of it in 1772.
+
+The field of discovery always appears to be completely occupied until
+the advent of a great man, who, even by his way of putting old and
+familiar facts, shows the paths along which discoveries must come, if at
+all. This faculty comes from profound reflection on the nature of the
+subject itself, from a sort of transmuting power which changes the words
+of the books into the things of reality. HERSCHEL'S paper on _Saturn_,
+in 1790, is an admirable example of this.
+
+HERSCHEL'S observations on _Saturn_ began in 1772. From 1790 to 1808 he
+published six memoirs on the figure, the ring, and the satellites of
+this planet. The spheroidal shape of the ball was first discovered by
+him, and we owe much of our certain knowledge of the constitution of the
+rings to his work. The sixth and seventh satellites, _Mimas_ and
+_Enceladus_, were discovered by him in 1789. The periods of rotation of
+the ball and of the ring were also fixed. In his conclusions as to the
+real figure of the rings, there is a degree of scientific caution which
+is truly remarkable, and which to-day seems almost excessive.
+
+In his paper of 1792, HERSCHEL shows that the most distant satellite of
+_Saturn_--_Japetus_--turns once on its axis in each revolution about its
+primary, just as our moon does. He says of this:
+
+    "I cannot help reflecting with some pleasure on the discovery of an
+    analogy which shows that a certain uniform plan is carried on among
+    the secondary planets of our solar system; and we may conjecture
+    that probably most of the satellites are governed by the same law;
+    especially if it be founded on such a construction of their figure
+    as makes them more ponderous towards their primary planets."
+
+I believe the last suggestion to have been the first statement of the
+possible arrangement of matter in satellites, which was afterwards so
+forcibly maintained by HANSEN in his theory of the moon. HANSEN'S
+researches show the consequences of such an arrangement, although they
+do not prove its existence.
+
+It should be recorded that the explanation which is to-day received of
+the belts and bands upon _Jupiter_, is, I believe, first found in
+HERSCHEL'S memoir on _Venus_ (1793). His memoir of 1797, on the
+changeable brightness of the satellites of _Jupiter_, has already been
+referred to. The times of the rotation of the satellites on their axes
+was first determined by HERSCHEL from these observations, which also
+contain accounts of the curious, and as yet unexplained, phenomena
+attending their appearances on the disc of the planet.
+
+HERSCHEL discovered in January, 1787, the two brighter satellites of
+_Uranus_, now called _Oberon_ and _Titania_. They are among the faintest
+objects in the solar system. A later discussion of all his observations
+led him to the belief that there were four more, and he gives his
+observations and computations in full. He says that of the existence of
+additional satellites he has no doubt. Of these four, three were
+exterior to the most distant satellite _Oberon_, the other was
+"interior" to _Titania_.
+
+It was not until 1834 that even _Oberon_ and _Titania_ were again
+observed (by Sir JOHN HERSCHEL) with a telescope of twenty feet, similar
+to that which had discovered them, and not until 1847 was the true state
+of this system known, when Mr. LASSELL discovered _Ariel_ and _Umbriel_,
+two satellites interior to _Titania_, neither of which was HERSCHEL'S
+"interior" satellite. In 1848 and later years Mr. LASSELL, by the aid of
+telescopes constructed by himself, fully settled the fact that only
+four satellites of this planet existed. In 1874 I examined the
+observations of HERSCHEL on his supposed "interior" satellite, thinking
+that it might be possible that among the very few glimpses of it which
+he recorded, some might have belonged to _Ariel_ and some to _Umbriel_,
+and that by combining rare and almost accidental observations of two
+satellites which really existed, he had come to announce the existence
+of an "interior" satellite which had no existence in fact. Such I
+believe to be the case. In 1801, April 17, HERSCHEL describes an
+interior satellite in the position angle 189 deg., distant 18" from
+the planet. At that instant _Umbriel_, one of Mr. LASSELL'S satellites,
+was in the position 191 deg., and distant 21" from _Uranus_, in the
+most favorable position for seeing it. The observation of 1794, March
+27, _may_ belong to _Ariel_. At the best the investigation is of passing
+interest only, and has nothing to do with the question of the discovery
+of the satellites. HERSCHEL discovered the two brighter ones, and it
+was only sixty years later that they were properly re-observed by Mr.
+LASSELL, who has the great honor of having added as many more, and who
+first settled the vexed question of satellites _exterior_ to _Oberon_,
+and this with a reflecting telescope made by himself, which is
+unequalled by any other of its dimensions.
+
+
+                    _Researches on the Nature of the Sun._
+
+In the introduction to his paper on the _Nature and Construction of the
+Sun and Fixed Stars_ (1795), HERSCHEL recounts what was known of the
+nature of the sun at that time. NEWTON had shown that it was the centre
+of the system; GALILEO and his successors had determined its rotation,
+the place of its equator, its real diameter, magnitude, density,
+distance, and the force of gravity on its surface. He says:
+
+    "I should not wonder if, considering all this, we were induced to
+    think that nothing remained to be added; and yet we are still very
+    ignorant in regard to the internal construction of the sun." "The
+    spots have been supposed to be solid bodies, the smoke of
+    volcanoes, the scum floating on an ocean of fluid matter, clouds,
+    opaque masses, and to be many other things." "The sun itself has
+    been called a globe of fire, though, perhaps, metaphorically." "It
+    is time now to profit by the observations we are in possession of.
+    I have availed myself of the labors of preceding astronomers, but
+    have been induced thereto by my own actual observation of the solar
+    phenomena."
+
+HERSCHEL then refers to the theories advanced by his friend, Prof.
+WILSON, of Glasgow, in 1774. WILSON maintained that the spots were
+depressions below the sun's atmosphere, vast hollows as it were, at the
+bases of which the true surface of the sun could be seen.
+
+The essence of his theory was the existence of two different kinds of
+matter in the sun: one solid and non-luminous--the nucleus--the other
+gaseous and incandescent--the atmosphere. Vacant places in the
+atmosphere, however caused, would show the black surface of the solid
+mass below. These were the spots. No explanation could be given of the
+_faculae_, bright streaks, which appear on the sun's surface from time
+to time; but his theory accounted for the existence of the black
+_nuclei_ of the spots, and for the existence of the _penumbrae_ about
+these. The penumbra of a spot was formed by the thinner parts of the
+atmosphere about the vacancy which surrounded the nucleus.
+
+This theory of WILSON'S was adopted by HERSCHEL as a basis for his own,
+and he brought numerous observations to confirm it, in the modified
+shape which he gave to it.
+
+According to HERSCHEL, the sun consisted of three essentially different
+parts. First, there was a solid nucleus, non-luminous, cool, and even
+capable of being inhabited. Second, above this was an atmosphere proper;
+and, lastly, outside of this was a layer in which floated the clouds, or
+bodies which gave to the solar surface its intense brilliancy:
+
+    "According to my theory, a dark spot in the sun is a place in its
+    atmosphere which happens to be free from luminous decompositions"
+    above it.
+
+The two atmospheric layers, which will be of varying thickness about a
+spot, will account for all the shades of darkness seen in the penumbra.
+Ascending currents from the solar surface will elevate certain regions,
+and may increase the solar activity near by, and will thus give rise to
+faculae, which HERSCHEL shows to be elevated above the general surface.
+It will not be necessary to give a further account of this theory. The
+data in the possession of the modern theorist is a thousand-fold that to
+be derived from HERSCHEL'S observations, and, while the subject of the
+internal construction of the sun is to-day unsettled, we know that many
+important, even fundamental, portions of his theory are untenable.
+A remark of his should be recorded, however, as it has played a great
+part in such theories:
+
+    "That the emission of light must waste the sun, is not a difficulty
+    that can be opposed to our hypothesis. Many of the operations of
+    Nature are carried on in her great laboratory which we cannot
+    comprehend. Perhaps the many telescopic comets may restore to the
+    sun what is lost by the emission of light."
+
+Arguments in favor of the habitability of both sun and moon are
+contained in this paper; but they rest more on a metaphysical than a
+scientific basis, and are to-day justly forgotten.
+
+
+             _Researches on the Motion of the Sun and of
+                    the Solar System in Space._
+
+In 1782 HERSCHEL writes, in regard to some of his discoveries of double
+stars:
+
+    "These may serve another very important end. I will just mention it,
+    though it is foreign to my present purpose. Several stars of the
+    first magnitude have been observed or suspected to have a proper
+    motion; hence we may surmise that our sun, with all its planets and
+    comets, may also have a motion towards some particular point of the
+    heavens. . . . If this surmise should have any foundation, it will show
+    itself in a series of some years in a kind of systematical parallax,
+    or change, due to the motion of the whole solar system."
+
+In 1783 he published his paper _On the Proper Motion of the Solar
+System_, which contained the proofs of his surmises of a year before.
+That certain of the stars had in fact a _proper_ motion had been well
+established by the astronomers of the eighteenth century. After all
+allowances had been made for the effects of precession and other
+displacements of a star's position which were produced by motions of the
+earth, it was found that there were still small outstanding differences
+which must be due to the motion of the star itself--its proper motion.
+The quantity of this motion was not well known for any star when
+HERSCHEL'S researches began. Before they were concluded, however,
+MASKELYNE had deduced the proper motions of thirty-six stars--the
+fundamental stars, so called--which included in their number _Sirius_,
+_Procyon_, _Arcturus_, and generally the brightest stars.
+
+It is _a priori_ evident that stars, in general, must have proper
+motions, when once we admit the universality of gravitation. That any
+fixed star should be entirely at rest would require that the attractions
+on all sides of it should be exactly balanced. Any change in the
+position of this star would break up this balance, and thus, in general,
+it follows that stars must be in motion, since all of them cannot occupy
+such a critical position as has to be assumed. If but one fixed star is
+in motion, this affects all the rest, and we cannot doubt but that
+every star, our sun included, is in motion by an amount which varies
+from small to great. If the sun alone had a motion, and the other stars
+were at rest, the consequence of this would be that all the fixed stars
+would appear to be retreating _en masse_ from that point in the sky
+towards which we were moving. Those nearest us would move more rapidly,
+those more distant less so. And in the same way, the stars from which
+the solar system was receding would seem to be approaching each other.
+If the stars, instead of being quite at rest, as just supposed, had
+motions proper to themselves, then we should have a double complexity.
+They would still appear to an observer in the solar system to have
+motions, and part of these motions would be truly proper to the stars,
+and part would be due to the advance of the sun itself in space.
+
+Observations can show us only the _resultant_ of these two motions.
+It is for reasoning to separate this resultant into its two components.
+At first the question is to determine whether the results of observation
+indicate any solar motion at all. If there is none, the proper motions
+of stars will be directed along all possible lines. If the sun does
+truly move, then there will be a general agreement in the resultant
+motions of the stars near the ends of the line along which it moves,
+while those at the sides, so to speak, will show comparatively less
+systematic effect. It is as if one were riding in the rear of a railway
+train and watching the rails over which it has just passed. As we recede
+from any point, the rails at that point seem to come nearer and nearer
+together.
+
+If we were passing through a forest, we should see the trunks of the
+trees from which we were going apparently come nearer and nearer
+together, while those on the sides of us would remain at their constant
+distance, and those in front would grow further and further apart.
+
+These phenomena, which occur in a case where we are sensible of our own
+motion, serve to show how we may deduce a motion, otherwise unknown,
+from the appearances which are presented by the stars in space.
+
+In this way, acting upon suggestions which had been thrown out
+previously to his own time by LAMBERT, MAYER, and BRADLEY, HERSCHEL
+demonstrated that the sun, together with all its system, was moving
+through space in an unknown and majestic orbit of its own. The centre
+round which this motion is directed cannot yet be assigned. We can
+only know the point in the heavens towards which our course is
+directed--"the apex of solar motion."
+
+By a study of the proper motions assigned by MASKELYNE to the brighter
+stars, HERSCHEL was able to define the position of the solar apex with
+an astonishing degree of accuracy. His calculations have been several
+times repeated with the advantage of modern analytical methods, and of
+the hundred-fold material now at our disposition, but nothing essential
+has been added to his results of 1805, which were based upon such scanty
+data; and his paper of 1782 contains the announcement of the discovery
+itself.
+
+His second paper on the _Direction_ and _Velocity_ of the solar system
+(1805) is the best example that can possibly be given of his marvellous
+skill in reaching the heart of a matter, and it may be the one in which
+his philosophical powers appear in their highest exercise. For sustained
+reflection and high philosophic thought it is to be ranked with the
+researches of NEWTON in the _Principia_.
+
+
+           _Researches on the Construction of the Heavens._
+
+HERSCHEL'S papers on the Construction of the Heavens, as he named it,
+extended over his whole scientific life. By this he specially means the
+method according to which the stars, the clusters, the nebulae, are
+spread through the regions of space, the causes that have led to this
+distribution, and the laws to which it is subjected.
+
+No single astronomical fact is unimportant in the light which it may
+throw on the scheme of the whole, and each fact is to be considered in
+this light. As an instance: his discovery of the variable star
+_[alpha] Herculis_, which has a period of sixty days, was valuable in
+itself as adding one more to the number of those strange suns whose
+light is now brighter, now fainter, in a regular and periodic order.
+But the chief value of the discovery was that now we had an instance of
+a periodic star which went through all its phases in sixty days, and
+connected, as it were, the stars of short periods (three to seven days)
+with those of very long ones (three hundred to five hundred days), which
+two groups had, until then, been the only ones known. In the same way
+all his researches on the parallaxes of stars were not alone for the
+discovery of the distance of any one or two single stars, but to gain a
+unit of celestial measure, by means of which the depths of space might
+be sounded.
+
+Astronomy in HERSCHEL'S day considered the bodies of the solar system as
+separated from each other by distances, and as filling a cubical space.
+The ideas of near and far, of up and down, were preserved, in regard to
+them, by common astronomical terms. But the vast number of stars seemed
+to be thought of, as they appear in fact to exist, lying on the surface
+of a hollow sphere. The immediate followers of BRADLEY used these fixed
+stars as points of reference by which the motions within the solar
+system could be determined, or, like LACAILLE and LALANDE, gathered
+those immense catalogues of their positions which are so indispensable
+to the science. MICHELL and HERSCHEL alone, in England, occupied their
+thoughts with the nature and construction of the heavens--the one in his
+study, the other through observation.[34] They were concerned with all
+three of the dimensions of space.
+
+In his memoir of 1784, HERSCHEL says:
+
+    "Hitherto the sidereal heavens have, not inadequately for the
+    purpose designed, been represented by the concave surface of a
+    sphere, in the centre of which the eye of an observer might be
+    supposed to be placed.
+
+    "It is true the various magnitudes of the fixed stars even then
+    plainly suggested to us, and would have better suited, the idea of
+    an expanded firmament of three dimensions; but the observations upon
+    which I am now going to enter still farther illustrate and enforce
+    the necessity of considering the heavens in this point of view. In
+    future, therefore, we shall look upon those regions into which we
+    may now penetrate by means of such large telescopes, as a naturalist
+    regards a rich extent of ground or chain of mountains containing
+    strata variously inclined and directed, as well as consisting of
+    very different materials. The surface of a globe or map, therefore,
+    will but ill delineate the interior parts of the heavens."
+
+HERSCHEL'S method of study was founded on a mode of observation which he
+called _star-gauging_. It consisted in pointing a powerful telescope
+toward various parts of the heavens, and ascertaining by actual count
+how thick the stars were in each region. His twenty-foot reflector was
+provided with such an eye-piece that, in looking into it, he saw a
+portion of the heavens about 15' in diameter. A circle of this size on
+the celestial sphere has about one quarter the apparent surface of the
+sun, or of the full moon. On pointing the telescope in any direction, a
+greater or less number of stars were visible. These were counted, and
+the direction in which the telescope pointed was noted. Gauges of this
+kind were made in all parts of the sky, and the results were tabulated
+in the order of right ascension.
+
+The following is an extract from the gauges, and gives the average
+number of stars in each field at the points noted in right ascension and
+north polar distance:
+
+  -----------------------------------------------------------------
+              |    N. P. D.       ||           |    N. P. D.
+      R. A.   |78 deg. to 80 deg. ||   R. A.   |92 deg. to 94 deg.
+              |  No. of Stars.    ||           | No. of Stars.
+  ------------|-------------------||-----------|-------------------
+      H.  M.  |                   ||  H.  M.   |
+      11   6  |       3.1         ||  15  10   |      9.4
+      12  31  |       3.4         ||  15  22   |     10.6
+      12  44  |       4.6         ||  15  47   |     10.6
+      12  49  |       3.9         ||  16   8   |     12.1
+      13   5  |       3.8         ||  16  25   |     13.6
+      14  30  |       3.6         ||  16  37   |     18.6
+  -----------------------------------------------------------------
+
+In this small table, it is plain that a different law of clustering or
+of distribution obtains in the two regions. Such differences are still
+more marked, if we compare the extreme cases found by HERSCHEL, as
+R. A. = 19h 41m, N. P. D. = 74 deg. 33', number of stars per field = 588;
+and R. A. = 16h 10m, N. P. D. = 113 deg. 4', number of stars = 1.1.
+
+The number of stars in certain portions is very great. For example, in
+the Milky Way, near _Orion_, six fields of view promiscuously taken gave
+110, 60, 70, 90, 70, and 74 stars each, or a mean of 79 stars per field.
+The most vacant space in this neighborhood gave 60 stars. So that as
+HERSCHEL'S sweeps were two degrees wide in declination, in one hour
+(15 deg.) there would pass through the field of his telescope 40,000 or
+more stars. In some of the sweeps this number was as great as 116,000
+stars in a quarter of an hour.
+
+When HERSCHEL first applied his telescope to the Milky Way, he believed
+that it completely resolved the whole whitish appearance into small
+stars. This conclusion he subsequently modified. He says:
+
+    "It is very probable that the great stratum called the Milky Way is
+    that in which the sun is placed, though perhaps not in the very
+    centre of its thickness.
+
+    "We gather this from the appearance of the Galaxy, which seems to
+    encompass the whole heavens, as it certainly must do if the sun is
+    within it. For, suppose a number of stars arranged between two
+    parallel planes, indefinitely extended every way, but at a given
+    considerable distance from each other; and calling this a sidereal
+    stratum, an eye placed somewhere within it will see all the stars in
+    the direction of the planes of the stratum projected into a great
+    circle, which will appear lucid on account of the accumulation of
+    the stars, while the rest of the heavens, at the sides, will only
+    seem to be scattered over with constellations, more or less crowded
+    according to the distance of the planes, or number of stars
+    contained in the thickness or sides of the stratum.
+
+    "If the eye were placed somewhere without the stratum, at no very
+    great distance, the appearance of the stars within it would assume
+    the form of one of the smaller circles of the sphere, which would be
+    more or less contracted according to the distance of the eye; and,
+    if this distance were exceedingly increased, the whole stratum might
+    at last be drawn together into a lucid spot of any shape, according
+    to the length, breadth, and height of the stratum.
+
+    "Suppose that a smaller stratum should branch out from the former in
+    a certain direction, and that it also is contained between two
+    parallel planes, so that the eye is contained within the great
+    stratum somewhere before the separation, and not far from the place
+    where the strata are still united. Then this second stratum will not
+    be projected into a bright circle like the former, but it will be
+    seen as a lucid branch proceeding from the first, and returning
+    into it again at a distance less than a semicircle. If the bounding
+    surfaces are not parallel planes, but irregularly curved surfaces,
+    analogous appearances must result."
+
+The Milky Way, as we see it, presents the aspect which has been just
+accounted for, in its general appearance of a girdle around the heavens
+and in its bifurcation at a certain point, and HERSCHEL'S explanation of
+this appearance, as just given, has never been seriously questioned. One
+doubtful point remains: are the stars scattered all through space? or
+are they near its bounding planes, or clustered in any way within this
+space so as to produce the same result to the eye as if uniformly
+distributed?
+
+HERSCHEL assumed that they were nearly equably arranged all through the
+space in question. He only examined one other arrangement, _viz._, that
+of a ring of stars surrounding the sun, and he pronounced against such
+an arrangement, for the reason that there is absolutely nothing in the
+size or brilliancy of the sun to cause us to suppose it to be the centre
+of such a gigantic system. No reason, except its importance to us
+personally, can be alleged for such a supposition. Every star will have
+its own appearance of a Galaxy or Milky Way, which will vary according
+to the situation of the star.
+
+Such an explanation will account for the general appearances of the
+Milky Way and of the rest of the sky, supposing the stars equally or
+nearly equally distributed in space. On this supposition, the system
+must be deeper where the stars appear most numerous.
+
+HERSCHEL endeavored, in his early memoirs, to explain this inequality of
+distribution on the fundamental assumption that the stars were nearly
+equably distributed in space. If they were so distributed, then the
+number of stars visible in any gauge would show the thickness of the
+stellar system in the direction in which the telescope was pointed.
+At each pointing, the field of view of the instrument includes all the
+visible stars situated within a cone, having its vortex at the
+observer's eye, and its base at the very limits of the system, the angle
+of the cone (at the eye) being 15'. Then the cubes of the
+perpendiculars let fall from the eye, on the plane of the bases of the
+various visual cones, are proportional to the solid contents of the
+cones themselves, or, as the stars are supposed equally scattered within
+all the cones, the cube roots of the numbers of stars in each of the
+fields express the relative lengths of the perpendiculars. A _section_
+of the sidereal system along any great circle can be constructed from
+the data furnished by the gauges in the following way:
+
+The solar system is within the mass of stars. From this point lines are
+drawn along the different directions in which the gauging telescope was
+pointed. On these lines are laid off lengths proportional to the cube
+roots of the number of stars in each gauge. The irregular line joining
+the terminal points will be approximately the bounding curve of the
+stellar system in the great circle chosen. Within this line the space is
+nearly uniformly filled with stars. Without it is empty space. A similar
+section can be constructed in any other great circle, and a combination
+of all such would give a representation of the shape of our stellar
+system. The more numerous and careful the observations, the more
+elaborate the representation, and the 863 gauges of HERSCHEL are
+sufficient to mark out with great precision the main features of the
+Milky Way, and even to indicate some of its chief irregularities.
+
+On the fundamental assumption of HERSCHEL (equable distribution), no
+other conclusion can be drawn from his statistics but the one laid down
+by him.
+
+This assumption he subsequently modified in some degree, and was led to
+regard his gauges as indicating not so much the _depth of the system_ in
+any direction, as the _clustering power or tendency_ of the stars in
+those special regions. It is clear that if in any given part of the sky,
+where, on the average, there are ten stars (say) to a field, we should
+find a certain small portion having 100 or more to a field, then, on
+HERSCHEL'S first hypothesis, rigorously interpreted, it would be
+necessary to suppose a spike-shaped protuberance directed from the
+earth, in order to explain the increased number of stars. If many such
+places could be found, then the probability is great that this
+explanation is wrong. We should more rationally suppose some real
+inequality of star distribution here. It is, in fact, in just such
+details that the method of HERSCHEL breaks down, and a careful
+examination of his system leads to the belief that it must be greatly
+modified to cover all the known facts, while it undoubtedly has, in the
+main, a strong basis.
+
+The stars are certainly not uniformly distributed, and any general
+theory of the sidereal system must take into account the varied tendency
+to aggregation in various parts of the sky.
+
+In 1817, HERSCHEL published an important memoir on the same subject, in
+which his first method was largely modified, though not abandoned. Its
+fundamental principle was stated by him as follows:
+
+    "It is evident that we cannot mean to affirm that the stars of the
+    fifth, sixth, and seventh magnitudes are really smaller than those
+    of the first, second, or third, and that we must ascribe the cause
+    of the difference in the apparent magnitudes of the stars to a
+    difference in their relative distances from us. On account of the
+    great number of stars in each class, we must also allow that the
+    stars of each succeeding magnitude, beginning with the first, are,
+    one with another, further from us than those of the magnitude
+    immediately preceding. The relative magnitudes give only relative
+    distances, and can afford no information as to the real distances at
+    which the stars are placed.
+
+    "A standard of reference for the arrangement of the stars may be had
+    by comparing their distribution to a certain properly modified
+    equality of scattering. The equality which I propose does not
+    require that the stars should be at equal distances from each other,
+    nor is it necessary that all those of the same nominal magnitude
+    should be equally distant from us."
+
+It consisted in allotting a certain equal portion of space to every
+star, so that, on the whole, each equal portion of space within the
+stellar system contains an equal number of stars. The space about each
+star can be considered spherical. Suppose such a sphere to surround our
+own sun. Its radius will not differ greatly from the distance of the
+nearest fixed star, and this is taken as the unit of distance.
+
+Suppose a series of larger spheres, all drawn around our sun as a
+centre, and having the radii 3, 5, 7, 9, etc. The contents of the
+spheres being as the cubes of their diameters, the first sphere will
+have 3 x 3 x 3 = 27 times the volume of the unit sphere, and will
+therefore be large enough to contain 27 stars; the second will have 125
+times the volume, and will therefore contain 125 stars, and so on with
+the successive spheres. For instance, the sphere of radius 7 has room
+for 343 stars, but of this space 125 parts belong to the spheres inside
+of it; there is, therefore, room for 218 stars between the spheres of
+radii 5 and 7.
+
+HERSCHEL designates the several distances of these layers of stars as
+orders; the stars between spheres 1 and 3 are of the first order of
+distance, those between 3 and 5 of the second order, and so on.
+Comparing the room for stars between the several spheres with the number
+of stars of the several magnitudes which actually exists in the sky, he
+found the result to be as follows:
+
+  --------------------------------------------------------
+    Order of  |  Number of   |             |  Number of
+    Distance. | Stars there  |  Magnitude. | Stars of that
+              | is Room for. |             |  Magnitude.
+  --------------------------------------------------------
+    1........ |      26      |      1      |      17
+    2........ |      98      |      2      |      57
+    3........ |     218      |      3      |     206
+    4........ |     386      |      4      |     454
+    5........ |     602      |      5      |   1,161
+    6........ |     866      |      6      |   6,103
+    7........ |   1,178      |      7      |   6,146
+    8........ |   1,538      |             |
+  ---------------------------------------------------------
+
+The result of this comparison is, that if the order of magnitudes could
+indicate the distance of the stars, it would denote at first a gradual
+and afterward a very abrupt condensation of them, at and beyond the
+region of the sixth-magnitude stars.
+
+If we assume the brightness of any star to be inversely proportional to
+the square of its distance, it leads to a scale of distance different
+from that adopted by HERSCHEL, so that a sixth-magnitude star on the
+common scale would be about of the eighth order of distance according to
+this scheme--that is, we must remove a star of the first magnitude to
+eight times its actual distance to make it shine like a star of the
+sixth magnitude.
+
+On the scheme here laid down, HERSCHEL subsequently assigned the _order_
+of distance of various objects, mostly star-clusters, and his estimates
+of these distances are still quoted. They rest on the fundamental
+hypothesis which has been explained, and the error in the assumption of
+equal intrinsic brilliancy for all stars affects these estimates. It is
+perhaps probable that the hypothesis of equal brilliancy for all stars
+is still more erroneous than the hypothesis of equal distribution, and
+it may well be that there is a very large range indeed in the actual
+dimensions and in the intrinsic brilliancy of stars at the same order of
+distance from us, so that the tenth-magnitude stars, for example, may be
+scattered throughout the spheres which HERSCHEL would assign to the
+seventh, eighth, ninth, tenth, eleventh, twelfth, and thirteenth
+magnitudes. However this may be, the fact remains that it is from
+HERSCHEL'S groundwork that future investigators must build. He found the
+whole subject in utter confusion. By his observations, data for the
+solution of some of the most general questions were accumulated, and in
+his memoirs, which STRUVE well calls "immortal," he brought the
+scattered facts into order and gave the first bold outlines of a
+reasonable theory. He is the founder of a new branch of astronomy.
+
+
+            _Researches for a Scale of Celestial Measures.
+                        Distances of the Stars._
+
+If the stars are _supposed_ all of the same absolute brightness, their
+brightness to the eye will depend only upon their distance from us. If
+we call the brightness of one of the fixed stars at the distance of
+_Sirius_, which may be used as the unity of distance, 1, then if it is
+moved to the distance 2, its apparent brightness will be one-fourth; if
+to the distance 3, one-ninth; if to the distance 4, one-sixteenth, and
+so on, the apparent brightness diminishing as the square of the distance
+increases. The distance may be taken as an order of magnitude. Stars at
+the _distances_ two, three, four, etc., HERSCHEL called of the second,
+third, and fourth magnitudes.
+
+By a series of experiments, the details of which cannot be given here,
+HERSCHEL determined the space-penetrating power of each of his
+telescopes. The twenty-foot would penetrate into space seventy-five
+times farther than the naked eye; the twenty-five foot, ninety-six
+times; and the forty-foot, one hundred and ninety-two times. If the
+seventh-magnitude stars are those just visible to the naked eye, and if
+we still suppose all stars to be of equal intrinsic brightness, such
+seventh-magnitude stars would remain visible in the forty-foot, even if
+removed to 1,344 times the distance of _Sirius_ (1,344 = 7 x 192).
+If, further, we suppose that the visibility of a star is strictly
+proportional to the total intensity of the light from it which strikes
+the eye, then a condensed cluster of 25,000 stars of the 1,344th
+magnitude could still be seen in the forty-foot at a distance where each
+star would have become 25,000 times fainter, that is, at about 158 times
+the distance of _Sirius_ (158 x 158 = 24,964). The light from the
+nearest star requires some three years to reach the earth. From a star
+1,344 times farther it would require about 4,000 years, and for such a
+cluster as we have imagined no less than 600,000 years are needed. That
+is, the light by which we see such a group has not just now left it.
+On the contrary, it has been travelling through space for centuries and
+centuries since it first darted forth. It is the ancient history of such
+groups that we are studying now, and it was thus that HERSCHEL declared
+that telescopes penetrated into time as well as into space.
+
+Other more exact researches on the relative light of stars were made by
+HERSCHEL. These were only one more attempt to obtain a scale of
+celestial distances, according to which some notion of the limits and of
+the interior dimensions of the universe could be gained. Two telescopes,
+_exactly equal_ in every respect, were chosen and placed side by side.
+Pairs of stars which were _exactly equal_, were selected by means of
+them. By diminishing the aperture of one telescope directed to a bright
+star, and keeping the other telescope unchanged and directed to a
+fainter star, the two stars could be equalized in light, and, from the
+relative size of the apertures, the relative light of this pair of stars
+could be accurately computed, and so on for other pairs. This was the
+first use of the method of _limiting apertures_. His general results
+were that the stars of the first magnitude would still remain visible to
+the naked eye, even if they were at a distance from us _twelve_ times
+their actual distance.
+
+This method received a still further development at his hands. He did
+not leave it until he had gained all the information it was capable of
+giving. He prepared a set of telescopes collecting 4, 9, 16, etc.
+(2 x 2, 3 x 3, 4 x 4, etc.), times as much light as the naked eye.
+These were to extend the determinations of distance to the telescopic
+stars. For example, a certain portion of the heavens which he examined
+contained no star visible to the naked eye, but many telescopic stars.
+We cannot say that no one of these is as bright in itself as some of our
+first-magnitude stars. The smallest telescope of the set showed a large
+number of stars; these must, then, be _twice_ as far from us, on the
+average, as the stars just visible to the naked eye. But first-magnitude
+stars, like _Sirius_, _Procyon_, _Arcturus_, etc., become just visible
+to the eye if removed to twelve times their present distance. Hence the
+stars seen in this first telescope of the set were between twelve and
+twenty-four times as far from us as _Arcturus_, for example.
+
+"At least," as HERSCHEL says, "we are certain that if stars of the size
+and lustre of _Sirius_, _Arcturus_, etc., were removed into the
+profundity of space I have mentioned, they would then appear like the
+stars which I saw." With the next telescope, which collected nine times
+more light than the eye, and brought into view objects three times more
+distant, other and new stars appeared, which were then (3 x 12)
+thirty-six times farther from us than _Arcturus_. In the same way, the
+seven-foot reflector showed stars 204 times, the ten-foot 344 times,
+the twenty-foot 900 times farther from us than the average
+first-magnitude star. As the light from such a star requires three years
+to reach us, the light from the faintest stars seen by the twenty-foot
+would require 2,700 years (3 x 900).
+
+But HERSCHEL was now (1817) convinced that the twenty-foot telescope
+could not penetrate to the boundaries of the Milky Way; the faintest
+stars of the Galaxy must then be farther from us even than nine hundred
+times the distance of _Arcturus_, and their light must be at least 3,000
+years old when it reaches us.
+
+There is no escaping a certain part of the consequences established by
+HERSCHEL. It is indeed true that unless a particular star is of the same
+intrinsic brightness as our largest stars, this reasoning does not apply
+to it; in just so far as the average star is less bright than the
+average brightness of our largest stars, will the numbers which HERSCHEL
+obtained be diminished. But for every star of which his hypothesis is
+true, we may assert that his conclusions are true, and no one can deny,
+with any show of reason, that, on the whole, his suppositions must be
+valid. On the whole, the stars which we call faint are farther from us
+than the brighter ones; and, on the whole, the brilliancy of our
+brightest and nearest stars is not very far from the brilliancy of the
+average star in space. We cannot yet define the word _very_ by a
+numerical ratio.
+
+The _method_ struck out by HERSCHEL was correct; it is for his
+successors to look for the special cases and limitations, to answer the
+question, At a certain distance from us, what are the variations which
+actually take place in the brilliancy and the sizes of stars? The answer
+to this question is to be found in the study of the clusters of regular
+forms, where we _know_ the stars to be all at the same distance from us.
+
+
+                    _Researches on Light and Heat, Etc._
+
+Frequently in the course of his astronomical work, HERSCHEL found
+himself confronted by questions of physics which could not be
+immediately answered in the state of the science at that time. In his
+efforts to find a method for determining the dimensions of the stellar
+universe, he was finally led, as has been shown, to regard the
+brightness of a star as, in general, the best attainable measure of its
+distance from us. His work, however, was done with telescopes of various
+dimensions and powers, and it was therefore necessary to find some law
+for comparing the different results among themselves as well as with
+those given by observations with an unassisted eye. This necessity
+prompted an investigation, published in 1800, in which, after drawing
+the distinction between absolute and intrinsic brightness, HERSCHEL gave
+an expression for the _space-penetrating power_ of a telescope. The
+reasoning at the base of this conception was as follows.
+
+The ratio of the light entering the eye when directed toward a star, to
+the whole light given out by the star, would be as the area of the pupil
+of the eye to the area of the whole sphere having the star as a centre
+and our distance from the star as a radius. If the eye is assisted by a
+telescope, the ratio is quite different. In that case the ratio of the
+light which enters the eye to the whole light, would be as the area of
+the mirror or object-glass to the area of the whole sphere having the
+star as a centre and its distance as a radius. Thus the light received
+by the _eye_ in the two cases would be as the area of the pupil is to
+the area of the object-glass. For instance, if the pupil has a diameter
+of two-fifths of an inch, and the mirror a diameter of four inches, then
+a hundred times as much light would enter the eye when assisted by the
+telescope as when unarmed, since the _area_ of the pupil is
+one-hundredth the _area_ of the objective.
+
+If a particular star is just visible to the naked eye, it will be quite
+bright if viewed with this special telescope, which makes it one hundred
+times more brilliant in appearance. If we could move the star bodily
+away from us to a distance ten times its present distance, we could thus
+reduce its brightness, as seen with the telescope, to what it was at
+first, as seen with the eye alone, _i. e._, to bare visibility. Moving
+the star to ten times its present distance would increase the surface of
+the sphere which it illuminates a hundred-fold. We cannot move any
+special star, but we can examine stars of all brightnesses, and thus
+(presumably) of all distances.
+
+HERSCHEL'S argument was, then, as follows: Since with such a telescope
+one can see a star ten times as far off as is possible to the naked eye,
+this telescope has the power of penetrating into space ten times farther
+than the eye alone. But this number ten, also, expresses the ratio of
+the diameter of the objective to that of the pupil of the eye,
+consequently the general law is that the _space-penetrating power_ of a
+telescope is found by dividing the diameter of the mirror in inches by
+two-fifths. The diameter of the pupil of the eye (two-fifths of an inch)
+HERSCHEL determined by many measures.
+
+This simple ratio would only hold good, however, provided no more light
+were lost by the repeated reflections and refractions in the telescope
+than in the eye. That light must be so lost was evident, but no data
+existed for determining the loss. HERSCHEL was thus led to a long series
+of photometric experiments on the reflecting powers of the metals used
+in his mirrors, and on the amount of light transmitted by lenses.
+Applying the corrections thus deduced experimentally, he found that the
+space-penetrating power of his twenty-foot telescope, with which he made
+his star-gauges, was sixty-one times that of the unassisted eye, while
+the space-penetrating power of his great forty-foot telescope was one
+hundred and ninety-two times that of the eye. In support of his
+important conclusions HERSCHEL had an almost unlimited amount of
+experimental data in the records of his observations, of which he made
+effective use.
+
+By far the most important of HERSCHEL'S work in the domain of pure
+physics was published in the same year (1800), and related to radiant
+heat. The investigation of the space-penetrating powers of telescopes
+was undertaken for the sole purpose of aiding him in measuring the
+dimensions of the stellar universe, and there was no temptation for him
+to pursue it beyond the limits of its immediate usefulness. But here,
+though the first hint leading to remarkable discoveries was a direct
+consequence of his astronomical work, the novelty and interest of the
+phenomena observed induced him to follow the investigation very far
+beyond the mere solution of the practical question in which it
+originated.
+
+Having tried many varieties of shade-glasses between the eye-piece of
+his telescope and the eye, in order to reduce the inordinate degree of
+heat and light transmitted by the instrument when directed towards the
+sun, he observed that certain combinations of colored glasses permitted
+very little light to pass, but transmitted so much heat that they could
+not be used; while, on the other hand, different combinations and
+differently colored glasses would stop nearly all the heat, but allow an
+inconveniently great amount of light to pass. At the same time he
+noticed, in the various experiments, that the images of the sun were of
+different colors. This suggested the question as to whether there was
+not a different heating power proper to each color of the spectrum. On
+comparing the readings of sensitive thermometers exposed in different
+portions of an intense solar spectrum, he found that, beginning with the
+violet end, he came to the maximum of light long before that of heat,
+which lay at the other extremity, that is, near the red. By several
+experiments it appeared that the maximum of illumination, _i. e._, the
+yellow, had little more than half the heat of the full red rays; and
+from other experiments he concluded that even the full red fell short of
+the maximum of heat, which, perhaps, lay even a little beyond the limits
+of the visible spectrum.
+
+    "In this case," he says, "radiant heat will at least partly, if not
+    chiefly, consist, if I may be permitted the expression, of invisible
+    light; that is to say, of rays coming from the sun, that have such a
+    momentum[35] as to be unfit for vision. And admitting, as is highly
+    probable, that the organs of sight are only adapted to receive
+    impressions from particles of a certain momentum, it explains why
+    the maximum of illumination should be in the middle of the
+    refrangible rays; as those which have greater or less momenta are
+    likely to become equally unfit for the impression of sight."
+
+In his second paper on this subject, published in the same year,
+HERSCHEL describes the experiments which led to the conclusion given
+above. This paper contains a remarkably interesting passage which
+admirably illustrates HERSCHEL'S philosophic method.
+
+    "To conclude, if we call light, those rays which illuminate objects,
+    and radiant heat, those which heat bodies, it may be inquired
+    whether light be essentially different from radiant heat? In answer
+    to which I would suggest that we are not allowed, by the rules of
+    philosophizing, to admit two different causes to explain certain
+    effects, if they may be accounted for by one. . . . If this be a true
+    account of the solar heat, for the support of which I appeal to my
+    experiments, it remains only for us to admit that such of the rays
+    of the sun as have the refrangibility of those which are contained
+    in the prismatic spectrum, by the construction of the organs of
+    sight, are admitted under the appearance of light and colors, and
+    that the rest, being stopped in the coats and humors of the eye, act
+    on them, as they are known to do on all the other parts of our body,
+    by occasioning a sensation of heat."
+
+We now know that the reasoning and conclusion here given are entirely
+correct, but they have for their basis only a philosophical conception,
+and not a series of experiments designed especially to test their
+correctness. Such an experimental test of this important question was
+the motive for a third and last paper in this department of physics.
+This paper was published in volume ninety of the _Philosophical
+Transactions_, and gave the results of two hundred and nineteen
+quantitative experiments.
+
+Here we are at a loss to know which to admire most--the marvellous skill
+evinced in acquiring such accurate data with such inadequate means, and
+in varying and testing such a number of questions as were suggested in
+the course of the investigation--or the intellectual power shown in
+marshalling and reducing to a system such intricate and apparently
+self-contradictory phenomena. It is true that this discussion led him to
+a different conclusion from that announced in the previous paper, and,
+consequently, to a false conclusion; but almost the only escape from his
+course of reasoning lay in a principle which belongs to a later period
+of intellectual development than that of HERSCHEL'S own time.
+
+HERSCHEL made a careful determination of the quantitative distribution
+of light and of heat in the prismatic spectrum, and discovered the
+surprising fact that not only where the light was at a maximum the heat
+was very inconsiderable, but that where there was a maximum exhibition
+of heat, there was not a trace of light.
+
+    "This consideration," he writes, "must alter the form of our
+    proposed inquiry; for the question being thus at least partly
+    decided, since it is ascertained that we have rays of heat which
+    give no light, it can only become a subject of inquiry whether some
+    of these heat-making rays may not have a power of rendering objects
+    visible, superadded to their now already established power of
+    heating bodies. This being the case, it is evident that the _onus
+    probandi_ ought to lie with those who are willing to establish such
+    an hypothesis, for it does not appear that Nature is in the habit of
+    using one and the same mechanism with any two of our senses. Witness
+    the vibration of air that makes sound, the effluvia that occasion
+    smells, the particles that produce taste, the resistance or
+    repulsive powers that affect the touch--all these are evidently
+    suited to their respective organs of sense."
+
+It is difficult to see how the fallacy of this argument could have been
+detected by any one not familiar with the fundamental physiological law
+that the nature of a sensation is in no wise determined by the character
+of the agent producing it, but only by the character of the nerves acted
+upon; but, as already intimated, this law belongs to a later epoch than
+the one we are considering. HERSCHEL thus finally concluded that light
+and radiant heat were of essentially different natures, and upon this
+supposition he explained all of the phenomena which his numerous
+experiments had shown him. So complete and satisfactory did this work
+appear to the scientific world, that for a long time the question was
+looked upon as closed, and not until thirty-five years later was there
+any dissent. Then the Italian physicist, MELLONI, with instrumental
+means a thousand times more delicate than that of HERSCHEL, and with a
+far larger store of cognate phenomena, collected during the generation
+which had elapsed, to serve as a guide, discovered the true law. This,
+as we have seen, was at first adopted by HERSCHEL on philosophical
+grounds, and then rejected, since he did not at that time possess the
+key which alone could have enabled him to properly interpret his
+experiments.
+
+It is well to summarize the capital discoveries in this field made by
+HERSCHEL, more particularly because his claims as a discoverer seem to
+have been strangely overlooked by historians of the development of
+physical science. He, before any other investigator, showed that radiant
+heat is refracted according to the laws governing the refraction of
+light by transparent media; that a portion of the radiation from the sun
+is incapable of exciting the sensation of vision, and that this portion
+is the less refrangible; that the different colors of the spectrum
+possess very unequal heating powers, which are not proportional to their
+luminosity; that substances differ very greatly in their power of
+transmitting radiant heat, and that this power does not depend solely
+upon their color; and that the property of diffusing heat is possessed
+to a varying degree by different bodies, independently of their color.
+Nor should we neglect to emphasize, in this connection, the importance
+of his measurements of the intensity of the heat and light in the
+different portions of the solar spectrum. It is the more necessary to
+state HERSCHEL'S claims clearly, as his work has been neglected by those
+who should first have done him justice. In his "History of Physics,"
+POGGENDORFF has no reference to HERSCHEL. In the collected works of
+VERDET, long bibliographical notes are appended to each chapter, with
+the intention of exhibiting the progress and order of discovery. But all
+of HERSCHEL'S work is overlooked, or indexed under the name of his son.
+One little reference in the text alone shows that his very name was not
+unknown. Even in the great work of HELMHOLTZ on physiological optics,
+HERSCHEL'S labors are not taken account of.
+
+It is easy to account for this seemingly strange neglect. HERSCHEL is
+known to this generation only as an astronomer. A study of his memoirs
+will show that his physical work alone should give him a very high rank
+indeed, and I trust that the brief summaries, which alone can be given
+here, will have made this plain.
+
+       *       *       *       *       *
+
+We may conclude from the time expended, the elaborate nature of the
+experiments involved, and the character of the papers devoted to their
+consideration, that the portion of HERSCHEL'S researches in physics
+which interested him to the greatest degree, was the investigation of
+the optical phenomena known as NEWTON'S rings. In 1792 he obtained the
+two object-glasses of HUYGHENS, which were in the possession of the
+Royal Society, for the purpose of repeating NEWTON'S experiments, and in
+1810 he read the last of his three papers on the subject.
+
+Sir ISAAC NEWTON had given some of his most vigorous efforts to the
+study of the phenomena of interference of light, which are exemplified
+in the colors of thin and of thick plates. The colors of thin plates are
+most conveniently studied in the regular form which they present when
+produced by a thin plate of air, limited on one side by a plane
+polished surface, and on the other by a spherical surface of long
+radius, such as the exterior surface of a convex lens, for example.
+The colors are then arranged in concentric circles, and, though others
+had so produced them before NEWTON, these rings have, ever since the
+publication of his remarkable work, been known by his name.
+
+To explain the phenomena, NEWTON was obliged to supplement his theory of
+the corpuscular nature of light, by supposing that the inconceivably
+minute particles constituting light are not always equally susceptible
+of reflection, but that they have periodically recurring "fits of easy
+reflection" and of "easy transmission." This conception, though by no
+means unphilosophical, seemed to HERSCHEL too artificial and improbable
+for ready acceptance, and his effort was to supply a more probable
+explanation.
+
+The developments of optical science have justified HERSCHEL in his
+objections, but we cannot accord to him must any considerable part in
+making clear the true nature of the phenomenon. Indeed, it must be
+recognized that his position was distinctly less advanced than that of
+NEWTON. That great philosopher announced the true law governing the
+relation between the color and the thickness of the film. HERSCHEL did
+not recognize such a relation. NEWTON showed exactly how the phenomenon
+depended upon the obliquity at which it was viewed. HERSCHEL found no
+place in his theory for this evident variation.
+
+In the series of experiments described in the first paper on this
+subject, HERSCHEL mistook the locus of a certain set of rings which he
+was observing. This mistake, though so slight as hardly to be detected
+without the guidance of the definite knowledge acquired in later times,
+not only vitiated the conclusion from the experiments, but gave an
+erroneous direction to the whole investigation. To him these experiments
+proved that NEWTON'S conception of a periodic phenomenon was untenable.
+Thus cut loose from all hypothesis, his fertility in ideas and ingenuity
+in experimentation are as striking as ever. He tried the effect of
+having a polished metal as one of the surfaces limiting the thin plate
+of air. Observing the so-called "blue bow" of NEWTON at the limit of
+total reflection in a prism, he was led to the discovery of its
+complement, the "red bow" by refraction. Here he thought he had found
+the solution of his problem, and attributed the rings to the reflection
+of the light which passed through in the red bow. Though mistaken, he
+had presented to the world of science two experiments which have since
+played very prominent parts in the undulatory theory of light, namely,
+the rings formed upon polished metal, and the bands produced by a thin
+plate near the critical angle.
+
+As in his later researches upon the nature of radiant heat, he was wrong
+in his conclusions, and perhaps with less excuse. His experiments were
+skilfully devised and most ingenious. His philosophizing was distinctly
+faulty. We can see not only that he was wrong, but exactly where he
+began to go wrong. Yet these papers are full of interest to the
+physicist, and by no means deserve the neglect into which they have
+fallen.
+
+
+               _Researches on the Dimensions of the Stars._
+
+HERSCHEL examined a number of bright stars, using extremely high
+magnifying powers, in order to determine whether the stars have sensible
+dimensions. In a good telescope stars present round and pretty uniformly
+illuminated disks. If these disks really represent the angular diameter
+of the stars, they should admit of magnifying, like other objects; but,
+instead of this, HERSCHEL found that they appeared smaller as the
+telescopic power was increased. He accordingly called the disk of light
+seen in the telescope a spurious disk. This singular phenomenon gave its
+discoverer a ready criterion for determining whether a small bright body
+has an appreciable size, or only impresses the sense of sight by virtue
+of its intrinsic brightness. If the first were the case, the apparent
+size would increase with increased magnifying power, while, if the
+angular dimensions were inappreciable, the apparent size would, on the
+contrary, diminish with additional magnifying. An occasion for using
+this criterion came in the first years of this century, with the
+discovery of three small planets having orbits lying between those of
+_Mars_ and _Jupiter_. HERSCHEL gave the name _Asteroids_ to these
+bodies. As the appropriateness of this term had been violently assailed,
+the discovery of _Juno_, in 1804, the third one of the group, led to a
+careful experimental study of the defining power of the telescope used,
+and of the laws governing the phenomena of spurious disks.
+
+With a telescope of about nine inches in aperture, HERSCHEL found that
+if _Juno_ subtended an angle greater than a quarter of a second of arc,
+a certain indication of the fact would have shown itself in the course
+of the experiments. This conclusion was a justification of the name
+Asteroid, since the appearance of the new planet was strictly stellar.
+On other grounds, a better name might have been selected.
+
+In the paper giving the results of the experiments, the phenomena of the
+spurious disks are very completely described; but they did not attract
+the attention which they deserved, and they only became an object of
+especial interest to students of physics when they were again studied by
+the famous German optician FRAUNHOFER, a generation later.
+
+Incidentally the experiments are of interest, as yielding us a measure
+of the excellence of HERSCHEL'S telescopes, and a measure which is quite
+independent of the keenness of his vision. From them we may be sure that
+the efficiency of the nine-inch mirror used was not sensibly less than
+that of the highest theoretically attainable excellence. In this
+connection, too, we may refer to the _Philosophical Transactions_ for
+1790, pp. 468 and 475, where HERSCHEL gives observations of both
+_Enceladus_ and _Mimas_ seen in contact with the ball of _Saturn_.
+I have never seen so good definition, telescopic and atmospheric, as he
+must have had on these occasions.
+
+
+              _Researches on the Spectra of the Fixed Stars._
+
+The spectroscope was applied by SECCHI to the study of the spectra of
+the fixed stars visible to the naked eye in the years 1863 to 1866.
+He examined the nature of the spectrum of each of the larger stars,
+and found that these stars could be arranged in three general classes or
+_types_. His results have been verified and extended by other
+astronomers, and his classification has been generally accepted.
+According to SECCHI, the lucid stars may be separated into three groups,
+distinguished by marked differences in their spectra. SECCHI'S Type I.
+contains stars whose spectra are like those of _Sirius_, _Procyon_, and
+_[alpha] Lyrae_; his Type II. stars like _Arcturus_ and _Aldebaran_;
+his Type III. stars like _[alpha] Orionis_.
+
+HERSCHEL also made some trials in this direction. In the _Philosophical
+Transactions_ for 1814 (p. 264), he says:
+
+    "By some experiments on the light of a few of the stars of the first
+    magnitude, made in 1798, by a prism applied to the eye-glasses of my
+    reflectors, adjustable to any angle and to any direction, I had the
+    following analyses:
+
+    "The light of _Sirius_ consists of red, orange, yellow, green, blue,
+    purple, and violet. _[alpha] Orionis_ contains the same colors,
+    but the red is more intense, and the orange and yellow are less
+    copious in proportion than they are in _Sirius_. _Procyon_ contains
+    all the colors, but proportionately more blue and purple than
+    _Sirius_. _Arcturus_ contains more red and orange, and less yellow
+    in proportion than _Sirius_. _Aldebaran_ contains much orange and
+    very little yellow. _[alpha] Lyrae_ contains much yellow, green,
+    blue, and purple."
+
+Here the essential peculiarities of the spectrum of each of the stars
+investigated by HERSCHEL is pointed out, and if we were to use his
+observations alone to classify these stars into types, we should put
+_Sirius_ and _Procyon_ into one type of stars which have "all the
+colors" in their spectra; _Arcturus_ and _Aldebaran_ would represent
+another group of stars, with a deficiency of yellow and an excess of
+orange and red in the spectrum; and _[alpha] Orionis_ would stand as
+a type of those stars with an excess of red and a deficiency of orange.
+_[alpha] Lyrae_ would represent a sub-group of the first class.
+
+HERSCHEL'S immediate object was not classification, and his observations
+are only recorded in a passing way. But the fact remains that he
+clearly distinguished the essential differences of the spectra of these
+stars, and that he made these observations in support of his statement
+that the fixed stars, "like the planets, also shine with differently
+colored light. That of _Arcturus_ and _Aldebaran_, for instance, is as
+different from the light of _Sirius_ and _Capella_ as that of _Mars_ and
+_Saturn_ is from the light of _Venus_ and _Jupiter_."
+
+Of course, no special discovery can be claimed for him on these few
+instances. We can see, however, a good example of the manner in which he
+examined a subject from every side, and used the most remote evidence
+exactly in its proper place and time.
+
+
+          _Researches on the Variable Emission of Light
+                  and Heat from the Sun._
+
+It is certainly a remarkable fact that HERSCHEL was the first observer
+to recognize the real importance of the aperture or diameter of a
+telescope. Before his time it was generally assumed that this element
+only conditioned the amount of light transmitted to the eye, or, in
+other words, merely determined the brightness of the image. Hence the
+conclusion that if an object is sufficiently bright, the telescope may
+be made as small as desired without loss of power. Thus, in observing
+the sun, astronomers before HERSCHEL had been accustomed to reduce the
+aperture of their telescopes, in order to moderate the heat and light
+transmitted. SCHEINER, it is true, nearly two centuries before the time
+we are considering, had invented a method for observing the sun without
+danger, still employing the full aperture. This was by projecting the
+image of the sun on a white screen beyond the eye-piece, the telescope
+being slightly lengthened. For special purposes this ingenious method
+has even been found useful in modern times, though for sharpness of
+definition it bears much the same relation to the more usual manner of
+observing, that a photographic picture does to direct vision.
+
+Although HERSCHEL saw the advantages of using the whole aperture of a
+telescope in such observations, the practical difficulties in the way
+were very great. We have noted his attempts to find screens which would
+effectively cut off a large portion of the heat and light without
+impairing vision, and have considered, somewhat in detail, the
+remarkable discoveries in radiant heat to which these attempts led him.
+His efforts were not unsuccessful. A green glass smoked, and a glass
+cell containing a solution of black writing ink in water--were found to
+work admirably.
+
+Thus provided with more powerful instrumental means than had ever been
+applied to the purpose, HERSCHEL turned his attention to the sun. In a
+very short time he exhausted nearly all there was to be discovered, so
+that since the publication of his last paper on this subject, in 1801,
+until the present time, there has been but a single telescopic
+phenomenon, connected with the physical appearance of the sun, which was
+unknown to HERSCHEL. That phenomenon is the frequent occurrence of a
+darker central shade or kernel in large spots, discovered by DAWES about
+1858.
+
+HERSCHEL, though observing a hundred and ninety years after the earliest
+discovery of sun spots, seems to have been the first to suspect their
+periodic character. To establish this as a fact, and to measure the
+period, was left for our own times and for the indefatigable observer
+SCHWABE. The probable importance of such a period in its relation to
+terrestrial meteorology was not only clearly pointed out by HERSCHEL,
+but he even attempted to demonstrate, from such data as were obtainable,
+the character of this influence.
+
+Perhaps no one thing which this great philosopher has done better
+exhibits the catholic character of his mind than this research. When the
+possible connection of solar and terrestrial phenomena occurred to him
+as a question to be tested, there were no available meteorological
+records, and he could find but four or five short series of
+observations, widely separated in time. To an ordinary thinker the task
+would have seemed hopeless until more data had been collected. But
+HERSCHEL'S fertile mind, though it could not recall lost opportunities
+for solar observations, did find a substitute for meteorological records
+in the statistics of the prices of grain during the various epochs.
+It is clear that the price of wheat must have depended upon the supply,
+and the supply, in turn, largely upon the character of the season.
+The method, as ingenious as it is, failed in HERSCHEL'S hands on account
+of the paucity of solar statistics; but it has since proved of value,
+and has taken its place as a recognized method of research.
+
+
+                    _Researches on Nebulae and Clusters._
+
+When HERSCHEL first began to observe the nebulae in 1774, there were
+very few of these objects known. The nebulae of _Orion_ and _Andromeda_
+had been known in Europe only a little over a hundred years.
+
+In 1784 MESSIER published a list of sixty-eight such objects which he
+had found in his searches for comets, and twenty-eight nebulae had been
+found by LACAILLE in his observations at the Cape of Good Hope. In the
+mere discovery of these objects HERSCHEL quickly surpassed all others.
+In 1786 he published a catalogue of one thousand new nebulae, in 1789 a
+catalogue of a second thousand, and in 1802 one of five hundred. In all
+he discovered and described two thousand five hundred and eight new
+nebulae and clusters. This branch of astronomy may almost be said to be
+proper to the HERSCHELS, father and son. Sir JOHN HERSCHEL re-observed
+all his father's nebulae in the northern hemisphere, and added many new
+ones, and in his astronomical expedition to the Cape of Good Hope he
+recorded almost an equal number in the southern sky.
+
+Of the six thousand two hundred nebulae now known the HERSCHELS
+discovered at least eight-tenths. The mere discovery of twenty-five
+hundred nebulae would have been a brilliant addition to our knowledge of
+celestial statistics.
+
+HERSCHEL did more than merely point out the existence and position of
+these new bodies. Each observation was accompanied by a careful and
+minute description of the object viewed, and with sketches and diagrams
+which gave the position of the small stars in it and near it.[36]
+
+As the nebulae and clusters were discovered they were placed in classes,
+each class covering those nebulae which resembled each other in their
+general features. Even at the telescope HERSCHEL'S object was not
+discovery merely, but to know the inner constitution of the heavens.
+His classes were arranged with this end, and they are to-day adopted.
+They were:
+
+  CLASS I. "Bright nebulae (288 in all).
+       II. "Faint nebulae (909 in all).
+      III. "Very faint nebulae (984 in all).
+       IV. "Planetary nebulae, stars with burs, with milky chevelure,
+              with short rays, remarkable shapes, etc. (79 in all).
+        V. "Very large nebulae (52 in all).
+       VI. "Very compressed and rich clusters of stars (42 in all).
+      VII. "Pretty much compressed clusters (67 in all).
+     VIII. "Coarsely scattered clusters of stars" (88 in all).
+
+The lists of these classes were the storehouses of rich material from
+which HERSCHEL drew the examples by which his later opinions on the
+physical conditions of nebulous matter were enforced.
+
+As the nebulae were discovered and classified they were placed upon a
+star-map in their proper positions (1786), and, as the discoveries went
+on, the real laws of the distribution of the nebulae and of the clusters
+over the surface of the sky showed themselves more and more plainly. It
+was by this means that HERSCHEL was led to the announcement of the law
+that the spaces richest in nebulae are distant from the Milky Way, etc.
+By no other means could he have detected this, and I believe this to
+have been the first example of the use of the graphical method, now
+become common in treating large masses of statistics.
+
+It is still in his capacity of an observer--an acute and wise one--that
+HERSCHEL is considered. But this was the least of his gifts. This vast
+mass of material was not left in this state: it served him for a
+stepping-stone to larger views of the nature and extent of the nebulous
+matter itself.
+
+His views on the nature of nebulae underwent successive changes. At first
+he supposed all nebulae to be but aggregations of stars. The logic was
+simple. To the naked eye there are many groups of stars which appear
+nebulous. _Praesepe_ is, perhaps, the best example. The slightest
+telescopic power applied to such groups alters the nebulous appearance,
+and shows that it comes from the combined and confused light of discrete
+stars. Other groups which remain nebulous in a seven-foot telescope,
+become stellar in a ten-foot. The nebulosity of the ten-foot can be
+resolved into stars by the twenty-foot, and so on. The nebulae which
+remained still unresolved, it was reasonable to conclude, would yield to
+higher power, and generally a nebula was but a group of stars removed to
+a great distance. An increase of telescopic power was alone necessary to
+demonstrate this.[37]
+
+    "Nebulae can be selected so that an insensible gradation shall take
+    place from a coarse cluster like the _Pleiades_ down to a milky
+    nebulosity like that in _Orion_, every intermediate step being
+    represented. This tends to confirm the hypothesis that all are
+    composed of stars more or less remote."
+
+So, at first, HERSCHEL believed that his twenty-foot telescope was of
+power sufficient to fathom the Milky Way, that is, to see through it and
+beyond it, and to reduce all its nebulosities to true groups of stars.
+
+In 1791 he published a memoir on _Nebulous Stars_, in which his views
+were completely changed. He had found a nebulous star, the sixty-ninth
+of his Class IV., to which his reasons would not apply. In the centre of
+it was a bright star; around the star was a halo gradually diminishing
+in brightness from the star outward, and perfectly circular. It was
+clear the two parts, star and nebula, were connected, and thus at the
+same distance from us.
+
+There were two possible solutions only. Either the whole mass was,
+_first_, composed of stars, in which case the nucleus would be
+enormously larger than the other stars of its stellar magnitude
+elsewhere in the sky, or the stars which made up the halo indefinitely
+small; or, _second_, the central nucleus was indeed a star, but a star
+surrounded with "a shining fluid, of a nature totally unknown to us."
+
+The long strata of nebulae, which he had before described under the name
+of "telescopic Milky Ways," might well be accounted for by masses of
+this fluid lying beyond the regions of the seventh-magnitude stars. This
+fluid might exist independently of stars. If it is self-luminous, it
+seems more fit to produce a star by its condensation, than to depend
+upon the star for its own existence. Such were a few of the theorems to
+which his discovery of this nebula led him. The hypothesis of an elastic
+_shining fluid_ existing in space, sometimes in connection with stars,
+sometimes distinct from them, was adopted and never abandoned. How well
+the spectroscope has confirmed this idea it is not necessary to say.
+We know the shining fluid does exist, and in late years we have seen the
+reverse of the process imagined by HERSCHEL. A star has actually, under
+our eyes, become a planetary nebula, and the cycle of which he gave the
+first terms is complete.
+
+In five separate memoirs (1802, 1811, 1814, 1817, and 1818) HERSCHEL
+elaborated his views of the sidereal system. The whole extent of his
+views must be gained from the extended memoirs themselves. Here only the
+merest outline can be given.
+
+In 1802 there is a marshaling of the various objects beyond our solar
+system. The stars themselves may be _insulated_, or may belong to
+_binary_ or _multiple_ systems, to _clusters_ and groups, or to grand
+groups like the Milky Way. Nebulae may have any of the forms which have
+been described; and, in 1811, he gives examples of immense spaces in the
+sky covered with diffused and very faint nebulosity. "Its abundance
+exceeds all imagination."[38] These masses of nebular matter are the
+seats of attracting forces, and these forces must produce condensation.
+When a nebula has more than one preponderating seat of attracting
+matter, it may in time be divided, and the double nebulae have had such
+an origin. When nebulae appear to us as round masses, they are in reality
+globular in form, and this form is at once the effect and the proof of a
+gravitating cause.
+
+The central brightness of nebulae points out the seat of the attraction;
+and the completeness of the approximation to a spherical form points out
+the length of time that the gravitating forces have been at work. Those
+nebulae (and clusters) which are most perfect in the globular form, have
+been longest exposed to central forces. The planetary nebulae are the
+oldest in our system. They must have a rotatory motion on their axes.
+
+By progressive condensation planetary nebulae may be successively
+converted into bright stellar nebulae, or into nebulous stars, and these
+again, by the effects of the same cause, into insulated or double stars.
+This chain of theorems, laid down in the memoir of 1811, is enforced in
+1814 with examples which show how the nebulous appearance may grow into
+the sidereal. HERSCHEL selects from the hundreds of instances in his
+note-books, nebulae in every stage of progress, and traces the effect of
+condensation and of clustering power through all its course, even to the
+final breaking up of the Milky Way itself.
+
+The memoirs of 1817 and 1818 add little to the general view of the
+physical constitution of the heavens. They are attempts to gain a scale
+of celestial measures by which we may judge of the distances of the
+stars and clusters in which these changes are going on.
+
+There is little to change in HERSCHEL'S statement of the general
+construction of the heavens. It is the groundwork upon which we have
+still to build. Every astronomical discovery and every physical fact
+well observed is material for the elaboration of its details or for the
+correction of some of its minor points. As a scientific conception it is
+perhaps the grandest that has ever entered into the human mind. As a
+study of the height to which the efforts of one man may go, it is almost
+without a parallel. The philosopher who will add to it to-day, will have
+his facts and his methods ready to his hands. HERSCHEL presents the
+almost unique example of an eager observer marshaling the multitude of
+single instances, which he himself has laboriously gathered, into a
+compact and philosophic whole. In spite of minor errors and defects, his
+ideas of the nature of the sidereal universe have prevailed, and are
+to-day the unacknowledged basis of our every thought upon it. Some of
+its most secret processes have been worked out by him, and the paths
+which he pointed out are those along which our advances must be made.
+
+In concluding this condensed account of HERSCHEL'S scientific labors,
+it behoves us to remember that there was nothing due to accident in his
+long life. He was born with the faculties which fitted him for the
+gigantic labors which he undertook, and he had the firm basis of energy
+and principle which kept him steadily to his work.
+
+As a practical astronomer he remains without an equal. In profound
+philosophy he has few superiors. By a kindly chance he can be claimed as
+the citizen of no one country. In very truth his is one of the few names
+which belong to the whole world.
+
+FOOTNOTES:
+
+[31] JAMES SHORT, F.R.S. (1710-1768), and JOHN DOLLOND, F.R.S.
+(1706-1761), were the most celebrated makers of telescopes of their day.
+The six-foot Newtonian reflectors of SHORT (aperture 9.4 inches), and
+the forty-six-inch achromatics of DOLLOND (aperture 3.6 inches), were
+highly esteemed. The Royal Observatory of Greenwich possessed, in 1765,
+one of each class. In a comparative trial of SHORT'S telescope, at
+Greenwich, and one of HERSCHEL'S first telescopes, the latter was
+adjudged greatly superior.
+
+[32] At least _one_ of these telescopes had the principal
+mirror made of glass instead of metal.--_Philosophical Transactions_,
+1803.
+
+[33] The following extract from FOURIER'S _Eloge_ of HERSCHEL
+is of interest in this connection. The sum first appropriated by the
+king was L2,000. This was afterwards raised to L4,000, and a sum of L200
+yearly was given for maintenance.
+
+"L'histoire doit conserver a jamais la reponse de ce prince a un
+etranger celebre [LALANDE?] qui le remerciait des sommes considerables
+accordees pour les progres de l'astronomie. 'Je fais les depenses de la
+guerre,' dit le roi, 'parcequ'elles sont necessaires; quant a celles des
+sciences, il m'est agreable des les ordonner; leur objet ne coute point
+des larmes, et honore l'humanite.'"
+
+LALANDE'S own account is a little different. He says the king exclaimed:
+"Ne vaut-il pas mieux employer son argent a cela qu'a faire tuer des
+hommes?"
+
+[34] The memoirs on the parallaxes of stars, written by various
+astronomers from 1750 to 1800, were mainly directed to the improvement
+of the methods, or to the discovery of the parallax of some particular
+star. For example, LACAILLE'S observations of _Sirius_, at the Cape of
+Good Hope, had resulted in a parallax of 9" for that star--a
+quantity over forty times too large.
+
+[35] HERSCHEL accepted, as did all his cotemporaries, the
+Newtonian or corpuscular theory of light.
+
+[36] Thus the position of small stars critically situated in
+the centre, or on the edges of the nebulae was always noted. Many of the
+descriptions are given in the published papers, but the publication of
+the diagrams would be an immense help to this branch of astronomy.
+D'ARREST in his reduction of HERSCHEL'S nebula observations (1856)
+writes: "Gewiss waere es vom hoechsten Interesse fuer die Entwickelung,
+welche hoffentlich auch dieser Zweig der beobachtenden Astronomie
+zukuenftig erhalten wird, wenn die HERSCHEL'Schen Beobachtungen in der
+Ausfuehrlichkeit in welcher sie, verschiedenen Andeutungen zufolge,
+_handschriftlich_ vorhanden sind, veroeffentlicht wuerden. Es schliesst
+sich dieser Wunsch in Betreff der Nebelflecken lebhaft an den an,
+welcher, schon vor einem Jahrzehnt nach Veroeffentlichung der 400 noch
+unedirten _star-gauges_ von gewichtigerer Seite her geaeussert wurde."
+In this all must agree who have a knowledge of the direction in which we
+must look for advances in the difficult and important questions of the
+distance, the motions, and the changes of the nebulae. Almost the only
+aid to be looked for from the older observations must come from such
+diagrams, and we may safely say that the publication of this priceless
+material, just as it stands, would carry our exact data back from 1833
+to 1786, or no less than forty-seven years.
+
+[37] Long after HERSCHEL had abandoned this idea, it continued
+current among astronomers. The successes of Lord ROSSE'S telescope
+perpetuated to the middle of the nineteenth century an erroneous view
+which HERSCHEL had given up in 1791.
+
+[38] These have never been re-observed. They should be sought
+for with a powerful refractor, taking special precautions against the
+illumination of the field of view from neighboring bright stars.
+HERSCHEL'S reflectors were specially open to illusions produced in this
+way. His observations probably will remain untested until some large
+telescope is used in the way he adopted, _i. e._, in sweeping.
+
+
+
+
+                             BIBLIOGRAPHY.
+
+
+I.--LIST OF THE PUBLISHED WRITINGS OF WILLIAM HERSCHEL ON ASTRONOMICAL
+    SUBJECTS.
+
+                       [In chronological order.]
+
+_N.B.--In general, translations and abstracts of those which appeared
+in periodicals are not noticed here. I have made exceptions in the
+more important cases._
+
+[Solution of a prize question. _See_ this book, page 46.]
+                              _Ladies' Diary_, 1779.
+
+
+Astronomical observations on the periodical star in _Collo Ceti_.
+                              _Phil. Trans._, 1780, p. 338.
+
+
+Astronomical observations relating to the mountains of the moon.
+                              _Phil. Trans._, 1780, p. 507.
+
+
+Astronomical observations on the rotation of the planets round their
+axes, made with a view to determine whether the earth's diurnal motion
+is perfectly equable.
+                              _Phil. Trans._, 1781, p. 115.
+
+
+Account of a comet. [Dated 13th March, 1781. This was _Uranus_.]
+                              _Phil. Trans._, 1781, p. 492.
+
+
+On the parallax of the fixed stars.
+                              _Phil. Trans._, 1782, p. 82.
+
+
+Catalogue of double stars.
+                       _Phil. Trans._, 1782, p. 112: translation in
+                         _Bode's Jahrbuch_, 1786, p. 187.
+
+
+Description of a lamp micrometer and the method of using it.
+                              _Phil. Trans._, 1782, p. 163.
+
+
+A paper to obviate some doubts concerning the great magnifying powers used.
+                              _Phil. Trans._, 1782, p. 173.
+
+
+A letter from WILLIAM HERSCHEL, Esq., F.R.S., to Sir JOSEPH BANKS,
+_Bart._, P.R.S.
+                              _Phil. Trans._, 1783, p. 1.
+
+
+Aus einem Schreiben des Hrn. HERSCHEL an mich [BODE], datirt London, den
+13ten August, 1783.
+[This is a letter forwarding HERSCHEL'S memoir on the Parallax of the
+Fixed Stars, etc.]
+                              _Bode's Jahrbuch_, 1786, p. 258.
+
+
+On the diameter and magnitude of the _Georgium Sidus_, with a
+description of the dark and lucid disk and periphery micrometers.
+                              _Phil. Trans._, 1783, p. 4.
+
+
+On the proper motion of the sun and solar system, with an account of
+several changes that have happened among the fixed stars since the time
+of Mr. FLAMSTEED.
+                              _Phil. Trans._, 1783, p. 247.
+                              _Bode's Jahrbuch_, 1787, p. 194, p. 224.
+
+
+Astronomische Nachrichten und Entdeckungen, aus einem franzoesischen
+Schreiben desselben an mich [BODE], datirt Datchet, nahe bey Windsor,
+den 18. Mai, 1784.
+
+[This letter is on the subject of the use of high magnifying powers, and
+gives a _resume_ of his recent papers.]
+                              _Bode's Jahrbuch_, 1787, p. 211.
+
+
+On the remarkable appearances at the polar regions of the planet _Mars_,
+the inclination of its axis, the position of its poles and its
+spheroidical figure; with a few hints relating to its real diameter and
+atmosphere.
+                              _Phil. Trans._, 1784, p. 233.
+
+
+Account of some observations tending to investigate the construction of
+the heavens.
+                              _Phil. Trans._, 1784, p. 437.
+
+
+[_Bode's Jahrbuch_, 1788, p. 246, has a summary of this paper by Baron
+VON ZACH. See, also, _Bode's Jahrbuch_, 1794, p. 213.]
+
+
+Catalogue of double stars.
+                              _Phil. Trans._, 1785, p. 40.
+
+
+On the construction of the heavens.
+                              _Phil. Trans._, 1785, p. 213.
+                              _Bode's Jahrbuch_, 1788, p. 238.
+                      See, also, _same_, 1787, p. 213, and 1794, p. 213.
+
+
+Aus einem Schreiben des Hrn. HERSCHEL an mich [BODE], datirt Clay Hall,
+nahe bey Windsor, den 20. Jul., 1785.
+[This is a letter forwarding two memoirs, and giving the prices of
+telescopes]
+                              _Bode's Jahrbuch_, 1788, p. 254.
+
+
+Catalogue of one thousand new nebulae and clusters of stars.
+                              _Phil. Trans._, 1786, p. 457.
+                              _Bode's Jahrbuch_, 1791, p. 157,
+                              and _same_, 1794, p. 213.
+
+
+Investigation of the cause of that indistinctness of vision which has
+been ascribed to the smallness of the optic pencil.
+                              _Phil. Trans._, 1786, p. 500.
+
+
+Remarks on the new comet [1786, II.].
+                              _Phil. Trans._, 1787, p. 4.
+
+
+[Letter from HERSCHEL to BODE on the discovery of two satellites to
+_Uranus_, dated Slough, 1787, Feb. 11.]
+                              _Bode's Jahrbuch_, 1790, p. 253.
+
+
+An account of the discovery of two satellites revolving round the
+_Georgian planet_.
+                              _Phil. Trans._, 1787, p. 125.
+                              _Bode's Jahrbuch_, 1791, p. 255.
+
+
+An account of three volcanoes in the moon.
+                              _Phil. Trans._, 1787, p. 229.
+                              _Bode's Jahrbuch_, 1791, p. 255.
+
+
+Note on M. MECHAIN'S comet. [1787, I.] [Added to preceding paper.]
+                              _Phil. Trans._, 1787, p. 232.
+
+
+On the _Georgian planet_ and its satellites.
+                              _Phil. Trans._, 1788, p. 364.
+                              _Bode's Jahrbuch_, 1793, p. 104.
+
+
+Observations on a comet [1788, II.].
+                              _Phil. Trans._, 1789, p. 151.
+
+
+Catalogue of a second thousand of new nebulae and clusters of stars, with
+a few introductory remarks on the construction of the heavens.
+                              _Phil. Trans._, 1789, p. 212.
+                              _Bode's Jahrbuch_, 1793, p. 104.
+                              Also, _same_, 1794, p. 150.
+
+
+Account of the discovery of a sixth and seventh satellite of the planet
+_Saturn_, with remarks on the construction of its ring, its atmosphere,
+its rotation on an axis, and its spheroidical figure.
+                              _Phil. Trans._, 1790, p. 1.
+                              _Bode's Jahrbuch_, 1793, p. 239;
+                              _same_, 1796, p. 88; 1797, p. 249.
+
+
+On the satellites of the planet _Saturn_, and the rotation of its ring
+on an axis.
+                              _Phil. Trans._, 1790, p. 427.
+
+
+On nebulous stars properly so called.
+                              _Phil. Trans._, 1791, p. 71.
+                              _Bode's Jahrbuch_, 1801, p. 128.
+
+
+On the ring of _Saturn_ and the rotation of the fifth satellite upon its
+axis.
+                              _Phil. Trans._, 1792, p. 1.
+                              _Bode's Jahrbuch_, 1796, p. 88.
+
+
+Miscellaneous observations.
+
+[Account of a comet], p. 23 [1792, I.].
+
+[On the periodical appearance of omicron Ceti], p. 24.
+
+[On the disappearance of the 55th _Herculis_], p. 26.
+
+[Remarkable phenomenon in an eclipse of the moon], p. 27.
+                              _Phil. Trans._, 1792, p. 23.
+
+
+Observations on the planet _Venus_.
+                              _Phil. Trans._, 1793, p. 201.
+
+
+Observations of a quintuple belt on the planet _Saturn_.
+                              _Phil. Trans._, 1794, p. 28.
+                              _Bode's Jahrbuch_, 1798, p. 90.
+
+
+Account of some particulars observed during the late eclipse of the sun.
+[1793, September 5th.]
+                              _Phil. Trans._, 1794, p. 39.
+
+
+On the rotation of the planet _Saturn_ upon its axis.
+                              _Phil. Trans._, 1794, p. 48.
+                              _Bode's Jahrbuch_, 1798, p. 74.
+
+
+On the nature and construction of the sun and fixed stars.
+                             _Phil. Trans._, 1795, p. 46.
+                             _Bode's Jahrbuch_, II. Suppl. Band, p. 65.
+
+
+Description of a forty-foot reflecting telescope.
+                             _Phil. Trans._, 1795, p. 347.
+                             _Bode's Jahrbuch_, III. Suppl. Band, p. 238.
+
+
+Additional observations on the comet. [1796, I.]
+                              _Phil. Trans._, 1796, p. 131.
+
+
+On the method of observing the changes that happen to the fixed stars;
+with some remarks on the stability of the light of our sun. To which is
+added a catalogue of comparative brightness for ascertaining the
+permanency of the lustre of stars.
+                              _Phil. Trans._, 1796, p. 166.
+                              _Bode's Jahrbuch_, 1809, p. 201.
+
+
+On the periodical star _[alpha] Herculis_; with remarks tending to
+establish the rotatory motion of the stars on their axes; to which is
+added a second catalogue of the comparative brightness of the stars.
+                              _Phil. Trans._, 1796, p. 452.
+                              _Bode's Jahrbuch_, 1809, p. 201.
+
+
+A third catalogue of the comparative brightness of the stars, with an
+introductory account of an index to Mr. FLAMSTEED'S observations of the
+fixed stars, contained in the second volume of the Historia Coelestis.
+To which are added several useful results derived from that index.
+                              _Phil. Trans._, 1797, p. 293.
+                              _Bode's Jahrbuch_, 1810, p. 143.
+
+
+Observations of the changeable brightness of the satellites of
+_Jupiter_, and of the variation in their apparent magnitudes, with a
+determination of the time of their rotatory motions on their axes. To
+which is added a measure of the diameter of the second satellite, and an
+estimate of the comparative size of all the four.
+                              _Phil. Trans._, 1797, p. 332.
+                              _Bode's Jahrbuch_, 1801, p. 103.
+
+
+On the discovery of four additional satellites of the _Georgium Sidus_.
+The retrograde motion of its old satellites announced, and the cause of
+their disappearance at certain distances from the planet explained.
+                              _Phil. Trans._, 1798, p. 47.
+                              _Bode's Jahrbuch_, 1801, p. 231.
+
+
+A fourth catalogue of the comparative brightness of the stars.
+                              _Phil. Trans._, 1799, p. 121.
+                              _Bode's Jahrbuch_, 1810, p. 143.
+
+
+On the power of penetrating into space by telescopes, with a comparative
+determination of the extent of that power in natural vision, and in
+telescopes of various sizes and constructions, illustrated by select
+observations.
+                              _Phil. Trans._, 1800, pp. 49-85.
+                              _Bode's Jahrbuch_, 1804, p. 231.
+
+
+Investigation of the powers of the prismatic colors to heat and
+illuminate objects, with remarks that prove the different refrangibility
+of radiant heat. To which is added an inquiry into the method of viewing
+the sun advantageously with telescopes of large apertures and high
+magnifying powers.
+                              _Phil. Trans._, 1800, pp. 255-283.
+                              _Bode's Jahrbuch_, 1804, p. 89.
+
+
+Experiments on the refrangibility of the invisible rays of the sun.
+                              _Phil. Trans._, 1800, pp. 284-292.
+                              _Bode's Jahrbuch_, 1804, p. 89.
+
+
+Experiments on the solar and on the terrestrial rays that occasion heat,
+with a comparative view of the laws by which light and heat, or rather
+the rays that occasion them, are subject, in order to determine whether
+they are the same or different.
+                               _Phil. Trans._, 1800, pp. 293-326, 437-538.
+                               _Gilbert Annal._, X. (1802), pp. 68-78;
+                               _same_, XII. (1803), pp. 521-546.
+
+
+Observations tending to investigate the nature of the sun, in order to
+find the causes or symptoms of its variable emission of light and heat,
+with remarks on the use that may possibly be drawn from solar
+observations.
+                       _Phil. Trans._, 1801, pp. 265-318.
+                       _Bode's Jahrbuch_, 1805, p. 218, and 1806, p. 113.
+
+
+Ueber den 7 Nebelfleck der 1sten classe des Herschel'schen Verzeichniss,
+und ueber _Ceres_ und _Pallas_, vom Herrn Doctor HERSCHEL, aus zwey
+Briefen desselben.
+                              _Bode's Jahrbuch_, 1805, p. 211.
+
+
+Additional observations tending to investigate the symptoms of the
+variable emission of the light and heat of the sun, with trials to set
+aside darkening glasses by transmitting the solar rays through liquids,
+and a few remarks to remove objections that might be made against some
+of the arguments contained in the former paper.
+                              _Phil. Trans._, 1801, pp. 354-362.
+
+
+Observations on the two lately discovered celestial bodies
+[_Ceres and Pallas_].
+                  _Phil. Trans._, 1802, pp. 213-232.
+                  _Nicholson Journal_, IV. (1808), pp. 120-130, 142-148.
+
+
+Catalogue of five hundred new nebulae, nebulous stars, planetary nebulae,
+and clusters of stars, with remarks on the construction of the heavens.
+                              _Phil. Trans._, 1802, pp. 477-528.
+                              _Bode's Jahrbuch_, 1807, p. 113.
+
+
+Observations of the transit of _Mercury_ over the sun's disk, to which
+is added an investigation of the causes which often prevent the proper
+action of mirrors.
+                              _Phil. Trans._, 1803, pp. 214-232.
+
+
+Account of the changes which have happened during the last twenty-five
+years in the relative situation of double stars, with an investigation
+of the cause to which they are owing.
+                              _Phil. Trans._, 1803, pp. 339-382.
+                              _Bode's Jahrbuch_, 1808, pp. 154-178.
+
+
+Continuation of the account of the changes that have happened in the
+relative situation of double stars.
+                              _Phil. Trans._, 1804, pp. 353-384.
+                              _Bode's Jahrbuch_, 1808, p. 226.
+
+
+Aus einem Schreiben des Herrn Doctor HERSCHEL, datirt Slough, bey
+Windsor, den 31. May, 1804.
+
+[Relates to his theory of the relation between the solar radiation and
+the price of wheat.]
+                              _Bode's Jahrbuch_, 1808, p. 226.
+
+
+Experiments for ascertaining how far telescopes will enable us to
+determine very small angles, and to distinguish the real from the
+spurious diameters of celestial and terrestrial objects, with an
+application of the results of those experiments to a series of
+observations on the nature and magnitude of Mr. HARDING'S lately
+discovered star [_Juno_ (1804),].
+                              _Phil. Trans._, 1805, pp. 31-70.
+
+
+On the direction and velocity of the motion of the sun and solar system.
+                              _Phil. Trans._, 1805, pp. 233-256.
+                              _Bode's Jahrbuch_, IV. Suppl. Band, p. 67.
+
+
+Observations on the singular figure of the planet _Saturn_.
+                              _Phil. Trans._, 1805, pp. 272-280.
+                              _Bode's Jahrbuch_, 1809, p. 197.
+
+
+On the quantity and velocity of solar motion.
+                              _Phil. Trans._, 1806, pp. 205-237.
+                              _Bode's Jahrbuch_, 1811, p. 224.
+
+
+Observations and remarks on the figure, climate, and atmosphere of
+_Saturn_ and its ring.
+                              _Phil. Trans._, 1806, pp. 455-467.
+                              _Gilbert Annal._, XXXIV. (1810), pp. 82-105.
+                              _Bode's Jahrbuch_, 1810, p. 228.
+
+
+Experiments for investigating the cause of the colored concentric rings
+discovered by Sir I. NEWTON between two object-glasses laid one upon
+another.
+                   _Phil. Trans._, 1807, pp. 180-233.
+                   _Annal. de Chimie_, LXX., 1809, pp. 154-181, 293-321;
+                   _same_, LXXI., 1809, pp. 5-40.
+
+
+Observations on the nature of the new celestial body [_Vesta_]
+discovered by Dr. OLBERS, and of the comet which was expected to appear
+last January in its return from the sun. [1806, II.]
+                              _Phil. Trans._, 1807, pp. 260-266.
+
+
+Observations of a comet [1807, I.] made with a view to investigate its
+magnitude and the nature of its illumination, to which is added an
+account of a new irregularity lately perceived in the apparent figure of
+the planet _Saturn_.
+                        _Phil. Trans._, 1808, pp. 145-163.
+                        _Gilbert Annal._, XXXVI. (1810), pp. 389-393.
+                        _Zach, Monat. Corresp._, XX. (1809), pp. 512-514.
+
+
+Continuation of experiments for investigating the cause of colored
+concentric rings and other appearances of a similar nature.
+                              _Phil. Trans._, 1809, pp. 259-302.
+
+
+Supplement to the first and second part of the paper of experiments for
+investigating the cause of colored concentric rings between
+object-glasses, and other appearances of a similar nature.
+                              _Phil. Trans._, 1810, pp. 149-177.
+                              _Gilbert Annal._, XLVI., 1814, pp. 22-79.
+
+
+Astronomical observations relating to the construction of the heavens,
+arranged for the purpose of a critical examination, the result of which
+appears to throw some new light upon the organization of the celestial
+bodies.
+                           _Phil. Trans._, 1811, pp. 269-336.
+                           _Journ. de Phys._, LXXV., 1812, pp. 121-167.
+
+
+Observations of a comet, with remarks on the construction of its
+different parts [1811, I.].
+           _Phil. Trans._, 1812, pp. 115-143.
+           _Journ. de Phys._, LXXVII., 1813, pp. 125-135.
+           _Zach, Monat. Corresp._, XXVIII., 1813, pp. 455-469, 558-568.
+           _Bode's Jahrbuch_, 1816, p. 185.
+
+
+Observations of a second comet, with remarks on its construction
+[1811, II.].
+                           _Phil. Trans._, 1812, pp. 229-237.
+                           _Nicholson Journ._, XXXV., 1813, pp. 193-199.
+                           _Bode's Jahrbuch_, 1816, p. 203.
+
+
+Astronomical observations relating to the sidereal part of the heavens,
+and its connection with the nebulous part, arranged for the purpose of a
+critical examination.
+                              _Phil. Trans._, 1814. pp. 248-284.
+                              _Bode's Jahrbuch_, 1818, pp. 97-118.
+
+
+A series of observations of the satellites of the _Georgian planet_,
+including a passage through the node of their orbits, with an
+introductory account of the telescopic apparatus that has been used on
+this occasion, and a final exposition of some calculated particulars
+deduced from the observations.
+                              _Phil. Trans._, 1815, pp. 293-362.
+                              _Bode's Jahrbuch_, 1819, p. 232-242.
+
+
+Astronomical observations and experiments tending to investigate the
+local arrangement of the celestial bodies in space, and to determine the
+extent and condition of the Milky Way.
+                              _Phil. Trans._, 1817, pp. 302-331.
+                              _Bode's Jahrbuch_, 1821, p. 149.
+
+
+Astronomical observations and experiments selected for the purpose of
+ascertaining the relative distances of clusters of stars, and of
+investigating how far the power of our telescopes may be expected to
+reach into space, when directed to ambiguous celestial objects.
+                              _Phil. Trans._, 1818, pp. 429-470.
+
+
+On the places of one hundred and forty-five new double stars (1821).
+                            _Mem. Roy. Ast. Soc._, 1, 1822, pp. 166-181.
+
+
+
+II.--LIST OF WORKS RELATING TO THE LIFE AND WRITINGS OF WILLIAM
+HERSCHEL.
+
+                 [Arranged alphabetically by authors.]
+
+_N.B.--In general, the notices of his life to be found in Encyclopaedias
+of Biography, etc., are not included here._
+
+
+ARAGO (F.)
+    Analyse de la vie et des travaux de Sir WILLIAM HERSCHEL [from
+_Annuaire du Bureau des Longitudes_, 1842]. Paris, 1843. 18mo.
+        [See also the _Annuaire_ for 1834, for an account of HERSCHEL'S
+        work on double stars.]
+
+
+ARAGO (F.)
+    Biographies of Distinguished Scientific Men. Translated by Admiral
+      W. H. SMYTH, Rev. B. POWELL, and ROBERT GRANT, Esq. HERSCHEL.
+        First series, p. 258. Boston, 1859. 8vo.
+
+
+ARAGO (F.)
+    HERSCHEL. [Translated from the French.]
+        Smithsonian Report. 1870. p. 197. 8vo.
+
+
+AUWERS (A.)
+    WILLIAM HERSCHEL'S Verzeichnisse von Nebelflecken und Sternhaufen
+      bearbeitet von A. AUWERS.
+        From the _Koenigsberg Observations_. 1862. Folio.
+
+
+BESSEL (F. W.)
+    Sir WILLIAM HERSCHEL. [From the _Koenigsberger Allgemeine Zeitung_, 1,
+      1843, No. 37, _et seq._, reprinted in his] _Abhandlungen_, vol iii.,
+      p. 468. Leipzig, 1876. 4to.
+
+
+D'ARREST (H. L.)
+    Verzeichniss von Sir WILLIAM HERSCHEL'S Nebelflecken _erster_ und
+      _vierter_ Classe, aus den Beobachtungen berechnet und auf 1850
+      reducirt.
+        _Abhandlungen der Math. Phys. Classe der K. Saechs Gesells. d.
+          Wissenschaften_, Band iii. [1857], p. 359.
+
+
+DUNKIN (E.)
+    Obituary Notices of Astronomers, p. 86. Sir WILLIAM HERSCHEL,
+      K.C.H., F.R.S., 1738-1822.
+        London, 1879. 12mo.
+
+
+FETIS (F. J.)
+    Biographie universelle des Musiciens [Article HERSCHEL].
+        Paris, 1835-37. 8vo.
+
+
+FORBES (J. D.)
+    Sir WILLIAM HERSCHEL [being Sec. 2 of Dissertation vi.].
+        Encyclopaedia Britannica, eighth edition.
+        Vol. i.,_Dissertations_, p. 838.
+
+
+FOURIER (J.)
+    Eloge historique de Sir WILLIAM HERSCHEL, prononce dans la seance
+      publique de l'Academie royale des sciences le 7 Juin, 1824.
+
+       _Historie de l'Academie Royale des Sciences de l'Institut de France_,
+         _tome_ vi., _annee_ 1823, p. lxi.
+
+
+HARDING (C. L.)
+    Des Herrn Dr. HERSCHEL'S Untersuchungen ueber die Natur der
+      Sonnenstrahlen, aus dem englischen uebersetzt. Erstes Heft.
+      [Translations from _Phil. Trans._, 1800.] Celle, 1801. 16mo.
+
+
+HASTINGS (C. S.)
+    See HOLDEN _and_ HASTINGS.
+
+
+HERSCHEL (Carolina.)
+    An Account of a new Comet. [1786, II.]
+        _Phil. Trans._, 1787, vol. LXXVII., p. 1.
+
+
+HERSCHEL (Carolina.)
+    An Account of the Discovery of a Comet. [1793, I.]
+        _Phil. Trans._, 1794, vol. LXXXIV., p. 1.
+
+
+HERSCHEL (Carolina.)
+    Account of the Discovery of a Comet. [1795, II.]
+        _Phil. Trans._, 1796, vol. LXXXVI., p. 131.
+
+
+HERSCHEL (Carolina.)
+    Catalogue of Stars taken from FLAMSTEED'S observations contained in
+      the second volume of his _Historia Coelestis_, and not inserted
+      in the British Catalogue; to which is added a collection of errata
+      which should be noticed in the same volume; with remarks by W.
+      HERSCHEL. London, 1798. Folio.
+
+
+HERSCHEL (Carolina.)
+    Verzeichniss von 74 Sternen FLAMSTEEDS von denen keine beobachtungen
+      in der _Hist. Coel. Brit._ vorkommen.
+        _Bode's Jahrbuch_, 1806, p. 255
+
+
+[HERSCHEL (Carolina.)]
+    [Notice of her Life.]
+        _Monthly Notices Roy. Ast. Soc._, vol. 8, p. 64; _also_, _Memoirs
+          Roy. Ast. Soc._, vol. 17, p. 120.
+
+
+[HERSCHEL (Carolina.)]
+    Memoir and Correspondence of CAROLINE HERSCHEL. By Mrs. JOHN
+      HERSCHEL. With portraits. London, 1876. 12mo.
+
+
+HERSCHEL (J. F. W.)
+    Article _Telescope_, in Encyclopaedia Britannica, eighth edition.
+      [This article (illustrated) gives most of the important features of
+      Sir WILLIAM HERSCHEL'S manner of grinding and polishing specula.]
+
+
+HERSCHEL (J. F. W.)
+    Catalogue of Nebulae and Clusters of Stars. [General and systematic
+      reduction of all Sir W. HERSCHEL'S observations brought into
+      connection with all other similar ones.]
+        _Phil. Trans._, 1864. Page 1. 4to.
+
+
+HERSCHEL (J. F. W.)
+    A Synopsis of all Sir WILLIAM HERSCHEL'S Micrometrical Measurements,
+      etc., of Double Stars, together with a Catalogue of those Stars . . .
+      for 1880.
+        _Mem. Roy. Ast. Soc._, vol. 35, p. 21. Lond., 1867. 4to.
+
+HERSCHEL (J. F. W.)
+    Additional Identifications of Double Stars in the Synoptic
+      Catalogues of Sir WILLIAM HERSCHEL'S Micrometrical Measurements,
+      etc.
+        _Monthly Notices Roy. Ast. Soc._, vol. 28, p. 151. London, 1868.
+         8vo.
+
+
+HERSCHEL (Mrs. John.)
+    Memoir and Correspondence of CAROLINE HERSCHEL. With portraits.
+        London, 1876. 12mo.
+
+
+HERSCHEL (W.)
+    [Solution of a prize question. _See_ this book, page 46.]
+        _Ladies' Diary_, 1779.
+
+
+HERSCHEL (W.)
+    The favorite Eccho Catch . . . and the preceding Glee [by S. LEACH].
+      To which is added the . . . Catch Sung by Three Old Women . . .
+      in the Pantomime called "The Genius of Nonsense" [by H. HARINGTON].
+        London, 1780(?). Obl. folio. [A MS. copy of this was kindly
+        furnished me by Dr. R. GARNETT, of the British Museum.]
+
+
+
+HERSCHEL (W.)
+    _Goettingen Magazin der Wissenschaften und Literatur_ (1783), vol.
+      iii., p. 4. LICHTENBERG and FORSTER, Editors.
+        [Letter from HERSCHEL, giving a brief account of his life. _See_
+        this book, page 3.]
+
+
+HERSCHEL (W.)
+    I. _Manuscripts in possession of the Royal Society._
+
+       1. A series of register sheets in which are entered up _all_ the
+          observations of _each_ nebula, copied _verbatim_ from the
+          sweeps. 2. A similar set of register sheets for MESSIER'S nebulae.
+          3. A general index of the 2,508 nebulae of W. HERSCHEL; given the
+          class and number, to find the general number. 4. An index list;
+          given the general number, to find the class and number.
+          5. A more complete list like 4. 6. A manuscript catalogue of
+          all the nebulae and clusters, reduced to 1,800, and arranged
+          in zones of 1 deg. in polar distance; by Miss CAROLINA HERSCHEL.
+          7. The original sweeps with the 20-foot reflector at Slough,
+          in three small 4to and four folio vols. of MS.
+
+
+II. _Manuscripts in possession of the Royal Astronomical Society._
+
+        This library contains "the whole series of autograph observations
+          of each double star [observed by HERSCHEL], brought together on
+          separate sheets by Sir WILLIAM HERSCHEL and Miss CAROLINA
+          HERSCHEL."
+
+
+[HERSCHEL (W.)]
+    Some Account of the Life and Writings of WILLIAM HERSCHEL, Esq.
+      [With a Portrait.]
+        The _European Magazine and London Review_ for January, 1785. 8vo.
+
+
+[HERSCHEL (W.)]
+        _Edinburgh Review_, vol. i., p, 426.
+            [A review of HERSCHEL'S memoir, "Observations on the two
+            lately discovered bodies," from _Phil. Trans._, 1802. _See_
+            this book, page 96.]
+
+
+[HERSCHEL (W.)]
+        "Sir WILLIAM HERSCHEL, from a London paper."
+
+        [This is a short obituary notice "furnished by a gentleman well
+          acquainted with Sir WILLIAM and his family, and its accuracy may
+          be relied on."]
+
+        _Niles' Register_, vol. 23, p. 154. Nov. 9, 1822. 8vo.
+
+
+[HERSCHEL (W.)]
+    Obituary: Sir WILLIAM HERSCHEL, Knt., LL.D., F.R.S.
+        _The Gentleman's Magazine and Historical Chronicle_, vol. xcii.,
+          1822, p. 274. 8vo.
+
+
+[HERSCHEL (W.)]
+        _Annual Register_, 1822, p. 289. 8vo.
+
+
+[HERSCHEL (W.)]
+    W. HERSCHEL'S Saemmtliche Schriften, Erster Band.
+        Ueber den Bau des Himmels. Mit 10 Kupfertafeln.
+          [Edited by J. W. PFAFF. A second edition was published in 1850.]
+          Dresden and Leipzig, 1828. 8vo.
+
+
+[HERSCHEL (W.)]
+        _New York Mirror_, vol. vi., 1829-30, p. 388.
+
+
+[HERSCHEL (W.)]
+        _Living Age_, vol. ii., p. 125 (1844). 8vo.
+        [Reprinted from _Chambers' Journal_.]
+
+
+[HERSCHEL (W.)]
+        _Foreign Quarterly Review_, vol. 31, p. 438. 8vo.
+
+        [Review of ARAGO'S "Analyse de la vie et des travaux de Sir WILLIAM
+          HERSCHEL."]
+
+
+[HERSCHEL (W.)]
+    ARAGO'S Life of HERSCHEL.
+
+        _Eclectic Museum_, vol. ii., p. 556. [Reprinted from the _Foreign
+          Quarterly Review_, vol. 31.]
+
+
+HOLDEN (E. S.)
+    On the Inner Satellites of _Uranus_. [Reduction of Sir WILLIAM
+      HERSCHEL'S observations.]
+
+        _Proceedings Amer. Assn. Adv. Science_, _August_, 1874, p. 49.
+         8vo.
+
+
+HOLDEN (E. S.)
+    Index Catalogue of Books and Memoirs relative to nebulae, clusters,
+      etc. _Smithsonian Miscellaneous Collections_, No. 311, pp. 19-38.
+    [Abstracts of Sir WILLIAM HERSCHEL'S memoirs (on nebulae) in the
+      _Philosophical Transactions_.]
+
+        Washington, 1877. 8vo.
+
+
+HOLDEN (E. S.) and C. S. HASTINGS.
+    A Subject-index and a Synopsis of the scientific writings of Sir
+      WILLIAM HERSCHEL. [Reprinted from the _Report_ of the Smithsonian
+      Institution (1879).]
+
+        Washington, 1881. 8vo.
+
+
+KRAFFT (J. G. F.)
+    Kurze Nachricht von dem beruehmten Astronomen HERSCHEL und einigen
+      seiner Entdeckungen.
+
+        Bayreuth, 1787. 8vo.
+
+PEIRCE (C. S.)
+    Photometric Researches. [A reduction of HERSCHEL'S observations on
+      the comparative brightness of the stars.] _Annals Harvard College
+      Observatory_, vol. ix.
+
+        Leipzig, 1878. 4to.
+
+
+SOMMER (G. M.)
+    WILLIAM HERSCHEL . . . ueber den Bau des Himmels; drei abhandlungen
+      aus dem englischen uebersetzt, nebst einem authentischen Auszug
+      aus KANTS allgemeiner Naturgeschichte und Theorie des Himmels.
+
+        Koenigsberg, 1791. 8vo.
+
+
+STRUVE (W.)
+    Etudes d'astronomie stellaire. Sur la voie lactee et sur la distance
+      des etoiles fixes. [P. 24 _et seq._ contains an elaborate review
+      of the construction of the heavens according to HERSCHEL.] St.
+      Petersburg, 1847. 8vo.
+
+
+WOLF (R.)
+    WILLIAM HERSCHEL. Zurich, 1867. 8vo.
+
+
+ZACH (F. von.)
+    Dr. WILLIAM HERSCHEL [translated from _Public Characters_ and
+      printed in ZACH'S _Monatlich Correspondenz_, 1802, part i., p. 70
+      _et seq._]
+
+
+III.--LIST OF THE PUBLISHED PORTRAITS OF WILLIAM HERSCHEL.
+
+_Artist_, MME. DUPIERY. _Engraver_, THOeNERT. 8vo. Early portrait. Some
+  copies in red. Profile.
+
+_Artist_, F. REHBURG. _Engraver_, F. W. BOLLINGER. 8vo. Late portrait.
+
+_Artist_, ----? _Engraver_, C. WESTERMAYR. 8vo. Medallion.
+
+_Artist_, C. BRAND. _Engraver_, ----? 8vo. Lithograph.
+
+_Artist_, ----? _Engraver_, J. SEWELL. 8vo. Profile, 1785.
+
+_Artist_, ----? _Engraver_, ----? 8vo. Profile.
+
+_Artist_, F. BONNEVILLE. _Engraver_, F. BONNEVILLE. 8vo. Profile.
+
+_Artist_, J. RUSSELL, R.A. _Engraver_, E. SCRIVEN. 8vo. Engraved from a
+  crayon in the possession of his son, and published by the S. D. U. K.
+  in the _Gallery of Portraits_, vol. 5.
+
+_Artist_, ----? _Engraver_, ----? 8vo. _European Magazine_, Jan., 1785.
+  This is a bust in profile, showing the left side of the face.
+
+_Artist_, ----? _Engraver_, THOMSON. 8vo. Published by Caxton, 1823.
+This must have been engraved before 1816 since the legend is WILLIAM
+HERSCHEL, LL.D., F.R.S.
+
+_Artist_, Lady GORDON. From the painting by ABBOTT in the National
+Portrait Gallery. _Engraver_, JOSEPH BROWN. 8vo. Published in memoir of
+CAROLINE HERSCHEL. This is of the date 1788, or thereabouts. _See_
+frontispiece.
+
+_Artist_, ----? _Engraver_, C. MUeLLER. 4to. Medallion, 1785(?).
+
+_Artist_, ----? _Engraver_, H. PINHAS. 4to. Legend in Russian.
+
+_Artist_, BAISCH. _Engraver_, ----? 4to. Lithograph.
+
+_Artist_, H. GREVEDON. _Engraver_, ----? Fol. Lithograph.
+
+_Artist_, ----? _Engraver_, F. MUeLLER. Fol.
+
+_Artist_, ABBOTT. _Engraver_, RYDER. Fol. 1788.
+
+_Artist_, J. BOILLY. _Engraver_, ----? Fol. 1822. Lithograph.
+
+_Artist_, ----? _Engraver_, J. GODBY. Fol.
+
+
+R. W. S. LUTWIDGE, Esq., F.R.A.S., has an original seal with a head of
+Sir WILLIAM HERSCHEL, which is shown on the title-page of this work. A
+cut of it has been courteously furnished me by JOHN BROWNING, Esq.,
+F.R.A.S., etc.
+
+In 1787 a bust of HERSCHEL was made by LOCKIE for Sir WILLIAM WATSON.
+
+A picture of HERSCHEL was painted by Mr. ARTAUD about the beginning of
+1819. A portrait of HERSCHEL by ABBOTT is in the National Portrait
+Gallery, London. There are no doubt many other paintings in England,
+though I can find notices of these only. The Royal Society of London has
+nearly a hundred portraits of its most distinguished members, but owns
+none of Sir WILLIAM HERSCHEL.
+
+
+
+
+                            INDEX OF NAMES.
+
+
+_N.B.--This index is intended to refer to the proper names occurring in
+the body of the work only, and not to the Bibliography._
+
+
+  Airy (Sir George), 17.
+
+  Alison (Sir Archibald), 111.
+
+  Arago (Francois), 49, 81, 139.
+
+  Artaud (M.), 114.
+
+  Aubert (Alexander), 52, 62, 63.
+
+
+  Baldwin (Miss), 115.
+
+  Banks (Sir Joseph), 56, 58, 64.
+
+  Bessel (F. W.), 127, 137.
+
+  Blagden (Dr.), 57.
+
+  Bonaparte (Napoleon), 108, 111.
+
+  Bradley (James), 51, 153.
+
+  Bruhl (Count von), 52.
+
+  Bulman (Mr.), 22, 115, 116.
+
+  Bunsen (Chevalier), 12.
+
+  Burney (Dr.), 82, 101, 102, 104, 105, 106.
+
+
+  Campbell (Thomas), 107.
+
+  Cassini (J. D.), 51.
+
+  Cropley (Mr.), 20.
+
+
+  Dalrymple (Mr.), 73.
+
+  D'Arblay (Madame), 100 _et seq._
+
+  Darlington (Earl of), 18.
+
+  Darquier, 51, 119.
+
+  D'Arrest (H. L.), 204.
+
+  Dawes (W. R.), 200.
+
+  De Luc (M.), 64.
+
+  De Luc (Mrs.), 100, 102.
+
+  Dollond (J.), 120.
+
+
+  Engelfield (Sir Harry), 57.
+
+
+  Farinelli (Miss), 38.
+
+  Flaugergues (H.), 51, 119.
+
+  Fleming (Miss), 42.
+
+  Fourier (J.), 124.
+
+  Frauenhofer (J.), 195.
+
+
+  Galileo, 50, 135.
+
+  George III., 64, 77, 124, 126.
+
+  Griesbach (George), 63.
+
+  Griesbachs (the), 62, 106.
+
+
+  Hansen (P. A.), 142.
+
+  Hastings (C. S.), 119.
+
+  Heberden (Dr.), 64.
+
+  Helmholtz (H.), 188.
+
+  Herschel (Abraham) [1651-1718], 6.
+
+  Herschel (Alexander) [1745-1821], 10, 12, 14, 15, 35, 38, 41, 57, 61,
+    62, 66, 72, 73, 114.
+
+  Herschel (Benjamin), 7.
+
+  Herschel (Carolina) [1750-1848], 2, 10, 11, 12, 16, 23, 29, 33, 41, 43,
+    68;
+    discovers five comets, 69, 70, 78, 83, 103, 105, 112, 113, 114, 115.
+
+  Herschel (Carolina), her _Memoir_ quoted, 2, 9, 13, 23, 29, 31, 34, 36,
+    41, 57, 61, 63, 64, 65, 70, 74.
+
+  Herschel (Dietrich), 9, 10, 11, 29, 42, 114.
+
+  Herschel (Eusebius), 7.
+
+  Herschel (Hans) [_circa_ 1600], 6.
+
+  Herschel (Isaac) [1707-1767], 7, 8, 29.
+
+  Herschel (Jacob) [1734-1792], 10, 11, 16, 23, 30.
+
+  Herschel (Sir John Frederick William) [1792-1871], 80, 103, 105, 114,
+    126, 127, 143, 203.
+
+  Herschel (Lady), 80, 102, 103, 105, 114.
+
+  Herschel (Major John), 2.
+
+  Herschel (Mrs. Mary Cornwallis), 2.
+
+  Herschel (Sophia Elizabeth), b. 1733, married Griesbach, 10.
+
+  Herschel (William), born 1738, November 15; 10.
+    oboist in the band of the Guards (1755), and goes to England for the
+      first time, returning in 1756, 16.
+    deserts from the Guards and goes to England (1757), 17.
+    organizes the band of the Durham militia (1760), 18.
+    leaves the band and lives with Dr. Miller, 19.
+    leads the public concerts at Wakefield and Halifax, 20.
+    organist at Halifax (1765), 22.
+    organist of the Octagon Chapel at Bath (1766), 24.
+    his musical writings, 26.
+    studies Smith's harmonies and optics, 28.
+    visits Hanover, August, 1772, 32.
+    hires a small telescope, 37.
+    makes his first telescope (1774), 38.
+    visits Hanover (1775?), 42.
+    1st review of the heavens, 39, 73.
+    2d review of the heavens, 73.
+    3d review of the heavens (1783), 73.
+    4th review of the heavens (1785), 74.
+    manufacture of telescopes, 40, 59, 75, 77, 120, 121, 122, 123, 124,
+      125, 126, 127.
+    moves to 19 New King St., Bath, 43.
+    conducts oratorios of Handel, 43.
+    begins astronomical _measures_ (1779), 44.
+    joins Philosophical Society of Bath, 45.
+    first published scientific writing (1779), 46.
+    first communication to the Royal Society (1780), 47.
+    discovery of _Uranus_ (1781, March 13), 49.
+    its effect on his career, 53.
+    elected a member of the Royal Society (1781), and receives the
+      Copley medal, 56.
+    attempts a thirty-foot reflector, 59.
+    goes to London, 1782 (May, June, July), 61.
+    appointed Royal Astronomer (L200), 1782, 67.
+    removes to Datchet, 1782, August 1, 67.
+    his assiduity, 72, 77, 79, 81.
+    his mechanical genius, 14, 41, 121.
+    cost of his telescopes, 77.
+    marries Mrs. John Pitt, _nee_ Baldwin (1783), 80.
+    only child born (1792), 80.
+    removes to Slough (1786), 81.
+    LL.D. (_Oxon._), 1786, 47.
+    his account of the discovery of _Uranus_ (1781, March 13), 4.
+    discovers two satellites to _Uranus_, 1787, Jan. 11, 84.
+    discovers two satellites to _Saturn_, 1789, August-September, 125.
+    invents machines for making reflectors (1788), 41.
+    began forty-foot telescope, 1785, finished it, 1789, 121.
+    biographical letter (1783), 3.
+    list of published portraits of him, 232.
+    value of his sister's assistance to him, 34.
+    letters to Carolina Herschel, 61, 63, 64, 114.
+    his personal character (1786-1800), 100 _et seq._
+    his relations to his cotemporaries, 85, 86, 87, 91, 94, 95, 96, 97,
+      98, 99.
+    list of writings relating to him and to his works, 225.
+    his literary skill, 45.
+    examples of his style, 83 _et seq._
+    failure of health, 112 _et seq._
+    created a Knight of the Royal Hanoverian Guelphic Order (1816), 115.
+
+  Herschel (Sir William), first president of the Royal Astronomical Society
+       (1821), 115.
+    his will, 114.
+    his death, August 25th, 1822, 116.
+    his epitaph, 117.
+    list of his scientific writings, 215.
+    review of his scientific labors, 118.
+    the improvement of telescopes and apparatus, 121.
+    the relative brightness of the stars; variable stars, 130.
+    researches on double stars, 134.
+    researches on planets and satellites, 140.
+    researches on the nature of the sun, 145, 186, 198.
+    the motion of the solar system in space, 149.
+    researches on the construction of the heavens, 154.
+    scale of celestial measures; distances of the stars, 170.
+    researches on light, heat, etc., 176.
+    researches on the dimensions of the stars, 193.
+    on the spectra of the fixed stars, 195.
+    on the variable emission of light and heat from the sun, 198.
+    researches on nebulae and clusters, 202.
+
+  Huyghens (C.), 50, 189.
+
+
+  King George III., 64, 77, 124, 126.
+
+
+  Lacaille (N. L.), 156, 202.
+
+  Lalande (Jerome), 28, 124, 156.
+
+  Lambert (J. H.), 153.
+
+  Lassell (W.), 143.
+
+  Lee (Miss), 61.
+
+  Lichtenberg (Herr), 3.
+
+  Lind (Dr. and Mrs.), 69.
+
+  Long (Dr.), 135.
+
+
+  Magellan (Herr), 3, 78.
+
+  Maskelyne (Nevil), 5, 51, 57, 62, 63, 150, 153.
+
+  Mayer (Christian), 94, 153.
+
+  Melloni (M.), 186.
+
+  Messier (C.), 202.
+
+  Michell (John), 52, 94, 137, 156.
+
+  Miller (Dr.), 19, 20, 21, 22.
+
+  Monson (Mrs.), 115.
+
+  Moritzen (Anna Ilse), m. Isaac Herschel, 7, 8.
+
+
+  Napoleon I., 108, 111.
+
+  Newton (Sir Isaac), 189, 190, 191, 192.
+
+
+  Olbers (William), 95.
+
+
+  Pabrich (Cappelmeister), 7.
+
+  Palmerston (Lord), 64.
+
+  Piazzi (Joseph), 75, 95.
+
+  Pierce (Charles S.), 132.
+
+  Pigott (J.), 119.
+
+  Poggendorff (J. G.), 188.
+
+
+  Ronzoni (Signor), 59.
+
+  Rosse (Lord), 122, 207.
+
+
+  Savary (M.), 139.
+
+  Secchi (Angelo), 195, 196.
+
+  Scheiner (C.), 199.
+
+  Schroeter (J. H.), 51, 77, 91, 92, 93.
+
+  Schwabe (H.), 201.
+
+  Short (James), 120.
+
+  Smith (Dr. Robert), 28.
+
+  Snetzler (Herr), 20, 21.
+
+  Struve (Otto von), 129.
+
+
+  Thomson (Thomas), 95.
+
+
+  Verdet (E.), 188.
+
+
+  Wainwright (Dr.), 20.
+
+  Walsh (Colonel), 62.
+
+  Watson (Sir William), 44, 58, 60, 64, 65, 66, 67, 75, 76.
+
+  Watt (James), 106.
+
+  Weld (R.), 126.
+
+  Wilson (Alexander), 52, 94, 146.
+
+
+  Zach (Baron von), 69.
+
+
+
+
+THE END.
+
+
+
+
+START OF TRANSCRIBER'S NOTES:
+
+I have used [alpha] to represent the greek letter used in the text.
+
+
+  page line  In the Original text, left as is.
+  227    3   uebersetzt
+  231   29   uebersetzt
+   18   24   Biographie universelle des musiciens
+  226   24   Biographie universelle des Musiciens
+  231   33   Koenigsberg, 1791. 8vo.
+  226    9   Koenigsberger Allgemeine Zeitung
+  195    4   Fraunhofer
+  235 index  Frauenhofer (J.), 195.
+  226   29   Vol.  (all other occurances are) vol.
+  238 index  Ronzoni (Signor), 59.
+   58   26   Ronzini
+
+
+  Original
+  page line  Original text                    Replaced with
+   65   23   ornamented.                      ornamented."
+  117   31   [C] for letter C reversed        CI[C]I[C]CCCXXII
+  216   25   den 18. May                      den 18. Mai
+  219   23   Suppl. Band., p. 238.            Suppl. Band, p. 238.
+
+
+END OF TRANSCRIBER'S NOTES:
+
+
+
+
+
+
+End of the Project Gutenberg EBook of Sir William Herschel: His Life and
+Works, by Edward Singleton Holden
+
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