P I O N E E R S O F P R O G R ES S

M EN O F S C I EN C E

E T ED S A R DI B " . CH P M AN , M . A D . s o. , F. .S .

H E R S C H E L

B " T H E R EV .

H ECT OR M ACPH ERSON

M . A

A"T H OR O F

" “ ’ ” " A T N M ERS F T -DA" A C ENT" " E S S xN A S T N S RO O O O , R S P ROGR RO OM" “ ” HE MAN E F M D E N A T N M" . T RO C O O R S RO O , ETC. ETC

L O N D O N S O C I E T Y F O R P R O M O T I N G C H R I S T I A N K N O W L E D G E

NEW YORK : T H E MACMILLAN COM PANY

T ENT CO N S .

C R AP .

A L" EA S I . E R Y R

E EL A S MA E" S R NO M E . R S CH R O R II H A T A T .

ERS CHEL A s PR OFE S S IONA L S RO NOM ER III . H A T

IV A ND AN . S OL R A PL ETAR" S T " DIE S

V TH E ONS R "C ON OF T H E EA V E NS . C T TI H

I S A R A C H V . TELL RE S E R E S

VI I LO S NG E A R S . C I Y

V PERS ONA LI " AN D NFL " E NC E III . T I

CHAPTER I .

S EARLY YEAR . — UN IVE RSAL history the histo ry o f what man has ” i s accomplished in this world , says Carlyle, at bottom ” O f the history the great men who have worked here . It must be admitted that Carlyle under-esti mated the labours of the innumerable lesser workers in al l depart o f ments human activity, that he overlooked the part played by mighty world - movements in the realm both o n of thought and of action and the i nfluence , even “ ” o f - great men , what has been called the time spirit . ’ — u al ified — Still , Carlyle s dictum slightly q is funda A s mentally true. great per onality is a creative force ; he gives more to his age and to posterity than he re i hi ce ves from s age or the ages before him . The history of astronomical science has been domi n ated i n a remarkable degree by great creative personal — ities pioneers of astronomical discovery. I n the front has rank of these distinguished men , posterity placed the name of William Herschel . The illustrious astronomer came Of an Old German one family , and was descended from Of three brothers , on o f who, account stead fast devotion to the principles o f o u t o f the Protestantism , were driven Moravia in early part Of the seventeenth century and compelled to o f seek refuge in Saxony. Hans Herschel , one these son brothers , settled at Pirna in Saxony. His second , 1 6 1 Abraham , born in 5 , acquired some distinction as a

- landscape gardener. He learned gardening in the (5) ’

Elector s gardens at Dresden , and was afterwards em 1 1 8 - ployed , until his death in 7 , at the country seat of

H ohentz iat z - " , in the principality of Anhalt erbst , near o f Magdeburg. According to the short account the “ family given by his illustrious grandson , he had also a O f a good knowledge rithmetic, writing , drawing, and music The last- named talent he bequeathed to his o H ohent z i at z o n 1 youngest son , Isaac, b rn at 4th Janu 1 0 w he ary, 7 7 . In a brief revie of his life which left n o f behi d him , Isaac explains that it was the desire his ’ parents that he should follo w i n his father s line of life. f After the death Of his ather, his elder brother Eusebius procured for him a situation in the gardens at "erbst . “ But he had, in his own words , lost all interest in ” “ oh nt ziat z gardening . As I had already at H e pro a i t cured violin and learned to play by ear, I took proper lessons at "erbst from an hautboy- player in the

- court band . I also bought an hautboy, and was never ’ so happy as when I could occupy myself with mu si o f

o f - At the age twenty one , having decided to follow out

- e . music as his life work , he went to B rlin to study Finding “ the Prussian service as a bandsman very bad ” and slavish , he went to Potsdam and took lessons for a year. From Potsdam he made his way to Brunswick , 1 1 and thence to Hanover, where in August, 7 3 , he was e - - ngaged as hautboy player i n the Foot guards . Hanover 1 2 i was desti ned to be his home , and i n 7 3 he marr ed o f o f t he Anna I lse Moritzen , the daughter a citizen Wens adt neighbouring town of t . They had a family Of — — ten, of whom six four sons and two daughters reached f he . O t maturity these , third , Friedrich Wilhelm , born on 1 th 1 8 o ne O f at Hanover s November , 7 3 , became e — o n e O f the greatest astronom rs indeed , the g reatest — f men of science o all time. I saac Herschel seem s to have been not only a man

O f . of high musical talent, but also wide general culture And despite the mother’ s dislike to learning and her EARLY YEARS 7

O f o f lack interest In Intellectual things , all the members — o f the the family with the exception elder daughter, — ’ Sophia inherited something Of their father s ability. — All four sons Jacob, William , Alexander, and Dieterich — were em inent musicians ; and the younger daughter, 1 6 0 acco m Caroline Lucretia, born th March, I 7 5 , also li shed has p in music , earned a distinction only second to - she that Of her distinguished brother, whose life work shared . H In her memoirs , written in Old age, Caroline erschel has given some interesting reminiscences o f her father . ” of My father, she says , was a great admirer astronomy and had some knowledge O f 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 be autiful constellations , after we had been gazing at a comet which was then visible . And I well remember with what de light he used to assist my brother William i n his various contrivances in the pursuit Of his philosophical was - studies, am ong which a neatly turned 4 inch globe , upon which the equator and ecliptic were engraved by my brother . ’ Despite his remarkable abilities , Isaac Herschel s whole life was spent in straitened c ircumstances : the post of bandsman in the Hanoverian Guards was not a lucrative o ne was , and he forced to augment his income by private tuition . In addition, his poverty was aggravated by

- . A 1 chronic ill health fter the battle Of Dettingen i n 74 3 , the Guards remained all night in the field . Isaac Herschel ’ of lay in a wet furrow, and as a result that night s ex o sure ff i m p , he contracted an asthmatical a ection which paired his health permanently and ultimately caused his

on 2 2 nd 1 6 . premature death March, 7 7 Having no wordl to t o y goods bequeath his children , he sought to educate them as completely as his limited means would allow . From their earliest days, their father instructed them in music . William Herschel , in the short account 8 i HER S CHEL

of his life already referred to , tells us th at his father “ taught me to play on the violin as soon as I was able s one to hold a mall made on purpose for me . Being also desirous o f giving all his children as good an edu cation as his very limited circumstances would allow , I o was at a proper time sent to a scho l where, besides religious instructions, all the boys received lessons in r reading, writing, and arithmetic ; and as I ve y readily v learned e ery task assigned me , I soon arrived at such a of e degree perfection, esp cially in arithmetic , that the master of the school made use of me t o hear younger boys say their lessons and to examine their arithmetical ” calculations . o f At the age fourteen and a half, young William o on H erschel entered the band of the Han verian Guards , 1 I st May , 7 5 3 . His school life was at an end , but

his education was only beginning. For over two years he received private lessons from a teacher named Hof a schl ger, who afterwards filled an important post at

Hamburg . These lessons i ncluded languages, logic , ’ e ethics , and metaphysics . In those early years Hersch l s

thirst for knowledge seems to have been insatiable. “ ” Although , he wrote in after years , I loved music to

excess and made considerable progress i n it , I yet de t ermi ned with a sort Of enthusiasm to devote every u moment I could spare to the p rsuit of knowledge, the which I regarded as Sovereign good, and in which I resolved to place all my future views of happiness in ” life . This intellectual keenness was undoubtedly stimulated e u by the hom environment . The mother, it is tr e, was hostile to intellectual ambition ; she was a typical Ger H a us m u man f , with no sympathy for aspirations ; but ,

as before mentioned , Isaac Herschel encouraged his sons

to talk and think on scientific and philosophical subjects.

Caroline Herschel , then a little girl about five years of

. age, has given a very interesting glimpse into this period EA RL" YEARS 9

she My brothers, says , were often introduced as solo performers and assistants in the orchestra Of the court , and I remember that I wa s frequently prevented from going to sleep by the lively criticism o n music o n m or o n coming home fro a concert , conversations philo sophical subjects which lasted fre quently till morning . Generally their conversation would branch ou t o n philo sophical subjects, when my brother William and my father often argued with such warmth that my mother ’ s interference became necessary when the names Leib nitz , 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. The family circle was temporarily dispersed in the end ’ 1 of 7 5 5 . The times were stormy : the Seven Years War was raging a French invasion of E n gland w as ex ected p , and the H anoverian Guards were drafted across the North Sea . Accordingly, Isaac Herschel and his t wo sons left Hanover with the regi ment. Embarking 1 6 at Cuxhaven in the end Of March 7 5 , they reached

Chatham after a passage Of sixteen days . The Guards t an d were encamped successively at Maidstone, Coxhea h , ’ n Rochester . The Herschels sojourn in E gland was by rofit ess no means p l . At Coxheath as well as at Maid “ t el l s u s e stone, H erschel , my father, my ldest brother and myself made several valuable acquaintances with e o f on famili s that were fond music, and which , mine and ’ t o my brother s return England , proved Of great service ” too n to us . At Maidstone, , you g William Herschel ’ “ purchased a copy of Locke s Essay on the Hu man ” — Understanding . The perusal of this volume the only — thing he took with him from England n ot only stimu lated his interest in philosophy, but familiarised him with the English language . o f 1 6 In the end 7 5 , the Guards were ordered back to

Hanover, owing to the French threat to the country.

Early in the following year, the regiment went into the I o HERSCHEL campaign which culminated in the disastrous battl e Of 2 6th 1 Hastenbeck, july, 7 5 7 . During the campaign they were many times forced to encamp in the wet furrows of ploughed fields . At Hastenbeck , the band o f was almost within reach gunshot . Accordingly, I saac hi Herschel advised his so n to consider s own safety. “ Young Herschel thereupon, i n his own words, left the engagement and took the road to H anover, but when I n o arrived there, I found that having passport I was i n ” danger O f being pressed for a soldier At that time of Herschel was not technically a soldier, but a member the band . Accordingly, he returned to the regiment, only to find that “ nobody had time to look after the — ” musicians they did not seem to be wanted . The ’ r on forced ma ches in the hot weather told the lad s health , “ and his father advised him to leave the service . I n ’ o n September, my father s opinion was, that as account of my youth I had not been sworn in when I was ad mi d tte u . to the G ards, I might leave the military service

Indeed , he had no doubt but that he could Obtain my dismission, and this he after some time actually procured 1 6 2 S Orcken (in 7 ) from General p , who succeeded General f ” Sommer eld . The formal discharge paper is i n existence and was printed for the first time i n the “ Collected Scientific 1 1 2 Papers of Sir William Herschel , published in 9 . ’ Dr . Dreyer , in his introductory sketch of Herschel s life, gives it as his Opinion that the existence of this formal discharge paper puts an end to the legend , too long and t oo readily believed , that he deserted from the army and that he received a formal pardon fo r this offence f rom George I I I o n the occasion of his first audience in 1 7 8 2 or Whether Herschel was technically a deserter not, it is f very di ficult to determine. I n some notes furnished in later years to the editor of a GOtti ngen scientific periodi “ : e cal , Herschel said In my fifteenth year, I enlist d in i m ilitary service, only remain ng in the army, however , E AR LY "EARS 1 1

until my nineteenth year, when I resigned and went ” t o O n over England . the other hand , as already noted , ’ he gives it as his father s view that he was not really a e i s 2 th soldi r at all . The formal discharge paper dated 9 1 6 2 so March , 7 , that ifWilliam Herschel was ever actually the a unit of army , the discharge paper merely registered an accomplished fact he had been ou t Of the army and o u t Of the country fo r four and a half years . Whether or not he was zjosof acto a soldier by virtue o f his position in the band , there can be no doubt that his departure for England was actuated by the d e sire to avoid being re

e to . call d the colours The evidence Of his sister Caroline,

e o f on . th n a little girl seven , is decisive this point I ” “ she can now comprehend, says, the reason why we o o ut o f little nes were continually sent the way, and why I had only by chance a passing glimpse of my brother e o f as I was sitting at the ntrance a street door, when he glided like a shadow along, wrapped in a greatcoat , followed by my mother with a parce l containing hi s ac co ut rement s suceeeded u n . After he had in passing noticed beyond the last sentinel at Herrenhausen , he ’ n changed his dress . My brother s keepi g himsel f so care fully from all notice was undoubtedly to avoid the danger Of being pressed , as all unengaged young men were forced into the service . Even the clergy, unless

n ot . they had livings , were exempted

At H am burg , William Herschel was joined by his

an d for . brother jacob , they embarked together England

Arriving in London , they were greatly assisted by the friends whom they had made on the occasion o f their pre viou s to visit . Nevertheless , they seem have had a hard no struggle. William Herschel had t hal f a guinea in his possession when he arrived in London . He went into a music shop and asked i f he could be of any use in copy d ing music . An opera was place in his hands, and his promptitude in returning the copy so impressed the master o f the shO p that he kept hi m in his employment fo r a 1 2 HER SCHEL

considerable time . jacob H erschel contrived to gain a

. At livelihood by teaching music length, the brothers found that they could not make a living in London . e Accordingly , Jacob decided to r turn to Hanover in the autumn of 1 7 5 9 to compete for a place in the court For orchestra , which he was successful in gaining. a time, William was , in his own words, involved in great ”

f . t di ficulties For unately , however, he succeeded in o f procuring an appointment in Yorkshire. The Earl o f Darlington, Colonel the Durham militia, was desirou s

Of obtaining a good musician as leader Of the band . ’ to an d re Herschel s name was brought his notice, he ceived the offer of the post, which he accepted and held for two years . These two years appear to have been very crowded. The brief entries i n his diary record the e composition Of various symphonies , and he s ems to have trave lled a great deal over the north of England . In 1 76 1 he appli ed for an i mportant post in Edinburgh “ the manager of the concerts intending to leave that place - and in anticipation o f receiving the appoint ment, he terminated his engagement with Lord Darling ton . However, Herschel was disappointed , as the concert manager altered his plans and decided t o remain at his O n post. arriving in Edinburgh , he records in his diary o I was intr duced to Mr. Hume, the metaphysician , and o f a few days after, at one their regular concert s, I was of o f appointed to lead the band musicians, while some my symphonies and solo concerts were performed . Mr. to Hume, who patronised my performance , asked me n dine with him , and accepting of his i vitation, I met a ” e considerabl company.

During the next few months , Herschel held temporary appointments at Newcastle and Pontefract, and in April , 1 6 2 o f 7 , he accepted a post as manager concerts at

for . Leeds, where he remained about four years During this time, his public engagements multiplied , and he was rapidly acquiring a notable position as a teacher EARLY YEARS 1 3

—i h of music which he was greatly aided by his friend , n Dr. Miller, organist at Do caster , who advised him to compete for the post o f organist at Halifax . In fo r th 66 his memorandum 7 March , 1 7 , Herschel states that the “ Messiah ” was performed at a private club was to Of chorus singers in Halifax , where it agreed rehearse the same oratorio every other Friday in order to perform it in the church at the Opening of a was for new organ erected there . I a candidate the

of . place organist, which , by the interest of the Messrs

Bates and many musical families I attended , I had great O n oth 1 66 w as hopes to obtain 3 August , 7 , he unani mou sl as y chosen organist, but he had already been asked to allow himself to be nominated as o rganist of the Octagon Chapel at Bath, where a new organ was in f h the o . ot process erection On 3 November, he played “ and : For organ at Halifax for the last time , notes the thirteen Sundays Of my being organist, I was paid thir ” th teen guineas . O n 9 December he arrived at Bath ; on th 1 6 and 4 October, 7 7 , the Octagon Chapel was e now on op ned, with Herschel as organist . He entered a busy and successful musical career. Pupils flocked to

-five him , and sometimes his lessons numbered thirty a week . In addition , he composed anthems and psalm

. 2 8th 1 6 tunes Under the date March , 7 7 , he noted , Taken a house from 2 5 th March to 2 9 th September in Beaufort Square Herschel had at last a settled home in England . th In his diary , under the date 5 April , H erschel “ notes : Went into mourning for the death o f my father The vicissitudes through which the family who passed have been graphically described by Caroline, ’ was , at her father s death , a girl Of seventeen . From her two — earliest years , Caroline had objects Of idolatry her father and her dear brother William ” the best and ” was dearest Of brothers . Her mother unimaginative or and unsympathetic , without interest in intellectual 1 4 HERSCHEL

“ was graceful accomplishments . It her certain belief, n Caroli e records, that my brother William would have returned to his country and my eldest brother not have ” o so l oked high i f they had had a little less learning . of Accordingly, Caroline became virtually the Cinderella the family— from earliest years a little neglected maid f- - o all work . Her eldest brother and sister showed her on little attention , and all her love was concentrated the father who wished to give her something like a polished ” on education, and her brother William , who invariably showed her kindness and affection . ’ After her father s death, she describes herself as having “ f ” “ fallen into a state o stu pefaction . She could not ” help feeling troubled about her future destiny . Her mother and her brother Jacob consistently under-esti mated her ; and domestic service seemed to be the only not e future in store for her. But William had forgott n 1 1 the little sister Of early years . In 77 he wrote home proposing that she should join him in Bath and become a useful singer for his winter concerts and oratorios Despite the opposition of her mother and the ridicule o f her brother Jacob, the plan materialised . In the autumn 1 2 W of 77 illiam Herschel arrived in Hanover, and at ’ the o f set off for close a fortnight s stay , England along on 2 8 th with Caroline . They arrived in Bath August, ’ 1 2 as her r 77 , and Caroline was at once installed brothe s housekeeper . She received instruction in English and too arithmetic as well as lessons in music . Already , , a ’ new interest had crept into Herschel s life . By way Of ” O f f relaxation , his sister tells us , we talked astronomy and the bright constellations with which I had made acquaintance during the fine nights we spent o n the ” Postwagen travelling through H olland. CHAPTE R I I .

S AS T " S T HER CHEL AMA E R A RONOMER .

I N 1 66 has th his diary, under the date 7 , Herschel e : “ l th following entries February g . Wheatley . Ob “ of 2 th. f servation Venus . February 4 Eclipse O the ’ a m Moon at 7 o clock . . Kirby . These are the first o f f indications his interest in astronomy . He had rom early years inherited from his father a taste for what

- might be called star gazing, and along with this he had had from youth a bent towards mathematical a s well as philosophical research . Even in his busiest years, he e never ceased to read and study in his l isure hours .

During the first years Of his stay in England , his fore to most care was master the English language . Next he t o to hi s acquired Italian , which he believed be essential profession . From this he passed on to the study Of Latin

Gr . and eek The latter language , however , he dropped , as leading me too far from my other favourite studie s by t oo o f o f taking up much my leisure . The theory music being connected with mathematics induced me very early to read in Germany all that had been written upon the n n ot subject of harmony ; and whe , long after my arrival in ’ ’ o f England , the valuable book Dr . Smith s Harmonics came into my hands , I perceived my ignorance , and had for was recourse to other authors information , by which I ” o n one f drawn from branch o mathematics to another. ’ “ ” e os After p rusing Smith s Harmonics, he became p ’ sessed O f a copy o f the same author s System of Optics The s cs se Of tudy of opti pas d into that astronomy , which ( 1 5 ) I 6 HERSCHEL was stimulated by “ Astronomy Explained upon Sir w ’ ” Isaac Ne ton s Principles , by James Ferguson , the ’ Scottish astronomer . Herschel s early interest in the en thu si latter science seems to have been revived . So

“’ a st ic o wn I did he become that, i n his words , resolved see own e to take nothing upon trust , but to with my ey s ” o f all that other men had seen before . At the time his ’ e sister s arrival at Bath , H rschel had plunged in earnest “ ” o f she into the study astronomy. He went to sleep , “ tells us, buried under his favourite authors ; and his first thoughts on rising were how to Obtain instru ments fo r viewing these objects himself o f which he had been ”

. 1 reading In May, 77 3 , he procured some Object glasses which he fitted into pasteboard tables . Caroline

Herschel , who at that time had no interest whatever in “ us : telescopic astronomy, tells 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 o f pasteboard for ” the glasses which were to arrive from London . At length , Herschel completed this instrument, 4 feet long , he which magnified forty times . With this , he records, e e observed Jupiter and its satellit s . Afterwards he mad — 1 0 ee other two refractors 5 and 3 f t long respectively. Herschel soon discovered for himsel f the great weakness Of the refracting telescope— the long tubes which were then necessary in order to counteract the effect of chro “ matic aberration . Finding the long tubes almost i m t e possible to manage, he turned his attention to the flectin two - g telescope , and in September hired a foot conven i Gregorian reflector, which he found much more e n t o f for . He decided to acquire a mirror his own , a 6 e en u l r e tube 5 or f et long . On q y he found ther “ f s were none in the market o o large a size. A ” “ e e one p rson , his sister t lls us , offered to make at a price much above what my brother thought proper to ” was n ot s r . He give . Herschel , however , di cou aged

1 8 HE RSCHEL

and grinding glasses . Every leisure moment was eagerly snatched at for resumi n g some work which was in progress , without taking time for changing dress , and many a lace ruffle was torn or bespattered by mol ten h pitc . From now onwards , Caroline proved herself the devoted assistant and helper of her brother, keeping hi s house for him , assisting him in music and in work of “ ” - . O f she telescope making By way keeping him alive , “ w as says, I constantly obliged to feed him by putting ” s e the victuals by bits into his mouth . This wa onc

- the case when , i n order to finish a seven foot mirror, he had not taken his hands from it for sixteen hours to “ gether . I n general he was never unemployed at meals , but was always at those times contriving or making draw ings 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 "uixote , Arabian ’ ’ of N ights Entertainments , the novels Sterne , Fielding, etc . serving tea and Supper without interrupting the work with which he was engaged . and sometimes lending a hand . My brother Alex . was absent from Bath fo r e some months every summer, but wh n at hom e he took much pleasure to execute some turning o r clock ’ ” maker s work for his brother . Herschel was not content with the construction o f one wo on re or t telescopes . The work went during the r f H ow mai n de o his stay in Bath . he contrived to continue the construction o f telescopes while making — long - continued surveys of the heavens all in the spare time which he was able to snatch from his busy career as — a professional musician must always remain more o r less Of a mystery. His earliest Observations were on the Moon and 1 6 o f O f planets . In 77 he made a number examinations wa the lunar surface , and three years later s engaged in r measuring the heights of the lunar mountains . F om 1 e 774 onwards, he carefully Obs rved Saturn , and in HERSC HEL AS A MATEUR ASTRONOME R 1 9

A 1 he pril , 7 77 , commenced to make sketches in pen and ink of the markings on the surface Of Mars , and in the following year o f those on Jupiter. H is attention was n ot confined to the members of the Solar System , and in 1 7 77 be com menced a series o f Observations on the — — or . a variable star , Omicron Mira Ceti As e rly as 1 778 he had conceived the idea o f attempting to deter mine by measures of close doubles the annual parallax o r apparent displacement of a star in the sky due t o the ’ earth s change o f position as it moves in its orbit . From

of . B e this parallax, the distance a star is determined ’ e at fore Hersch l s ti me, astronomers had made many e n t mpts to measure stellar parallax , but owi g to the great distance O f even the nearest stars and the co nse e o f becau se ' o f qu nt smallness the displacement, and also ve e o f the comparati i mp rfection astronomical instruments , f all these ef orts had failed . Herschel was particularly the e interested in problem , and made several att mpts to was n ot 1 8 8 solve it , but was unsuccessful . It until 3 that the first determinations o f stellar parallax were ’ e made . Herschel s attempts w re not altogether in vain , e for how ver , while tackling the problem , he was led to o f the study double stars , which resulted , after many e o ne . the y ars , in of his greatest discoveries At same time he executed his first review o f the heavens with his

- w e e 7 foot N e tonian refl ctor. The review only extend d to the first four magnitudes it was in itself a mere be

n was n - ginni g , but it the starti g point Of his work o n stellar distribution . Herschel soon became known to the cultu red public o f Bath, not only as a prominent musician , but also as o f an amateur astronomer considerable eminence . His introducti o n to literary and scientific circles in the town

o n e. hi s was a somewhat unconventional I n diary, 1 under the date December, 779 , there occurs the follow “ : o f ing entry About the latter end this month , I happened to be engaged o n a series of Observations on 20 HERSCHEL

o f the lunar mountains, and the Moon being in front my

- house late in the evening , I brought my 7 foot reflector to ob into the street , and directed it the object of my servati on s . While I was looking into the telescope , a gentleman coming by the place where I was stationed stopped to look at the instrument. When I took my O ff o eye the telescope, he very p litely asked i f he might be permitted to look in , and expressed great sat isfaction at the view . Next morning, the gentleman , who proved n e to be Dr. Watso , jun . (now Sir William), call d at my house to thank me for my civility in showing him the d Moon, and tol me that there was a Literary Society then forming at Bath and invited me to become a mem ” ber , to which I readily consented . 1 8 0 — the About the middle of January, 7 , this society e — e e Philosophical Soci ty of Bath b gan its m etings . e Herschel not only attended th se, but contributed a — — considerable number of papers thirty- one in all in the e o r o f e course of the next two y ars . One two thes e e o f d alt with astronomical subjects, such as the h ight e the lunar mountains , and the variable star Mira C ti ; but most Of them were on metaphysical and physical ” o f subjects , such as The Utility Speculative Enquiries , “ ” “ n O n the Existence Of S pace , and Experime ts in Light These were nearly all published in 1 9 1 2 in “ the Collected Scientific Papers o f Sir William Her ’ schel Through Dr. Watson s influence , Herschel was to introduced scientific circles in London , and he for warded four communications to the Royal Society before o n he was elected a Fellow. These were, a paper ” “ 1 1 th 1 8 0 o n Mira Ceti , read May, 7 the Mountains ” o n of the Moon , read the same day ; the Rotation Of the planets on their Axes , with a view to determine ’ ” whether the Earth s diurnal motion is perfectly equable , — a remarkable and ingenious pape r bea ring the stamp — o f his own peculiar methods of investigation read 1 1 th ” 1 8 1 “ 2 6th January, 7 ; and Account of a Comet , read 1 8 1 April , 7 . HERSCHEL AS A MATEUR ASTRO N OMER 2 1

The last- named paper gave an account o f the discovery ’ - which marked the turning point in Herschel s career . 1 1 n On 7th August, 779 , he commenced his seco d review of - the heavens . This review was made with his 7 foot o f 6 2 telescope inches aperture , and included stars down to the eighth magnitude ; its main purpose was t o 1 1 8 1 register double stars . On Tuesday , 3 th March , 7 , o f his in the course this review , he jotted down in journal o n : the f llowi g note, in somewhat doubtful English In " he the quartile near eta Tauri , t lowest Of two is a curious either nebulous star or perhaps a comet. A ’ small star follows the comet at two - thirds o f the field s ” distance . I n the paper afterwards communicated to the Royal Society, he explained that he perceived a star “ which appeared visibly larger than the rest : bein g struck with its uncommon magnitude, I compared it to H Geminorum and the small star in the quartile b e so tween Auriga and Gemini , and finding it much larger ” o f than either them , suspected it to be a comet . On 1 “ Saturday, 7th March , he wrote , I looked for the o r e fo r comet n bulous star, and found that it is a comet, ” has 1 he i t changed its place . By Monday, the 9 th , found that the supposed comet moves according to the o f order the signs, and its orbit declines but little from the ecliptic ” The discovery was soon communicated to the Observa o f tories Greenwich and Oxford . Maskelyne , the As trono mer- th Royal , wrote to Dr . Watson on the 4 April “ e that he had Observed the strang object, very different ” o f o r saw from any comet I ever read any description . “ On 2 3 rd April he wrote to H e rschel : I t is as likely to be a regular planet moving i n an orbit nearly circular round the Sun as a comet moving in a very eccentric ellipsis and he immediately notified the French o f astronomers the discovery. Messier, the most famous on 1 6 Observer Of comets , com menced Observations th A hi s a wa b pril , and ex mple s followed y Lalande, 2 2 H ERSCHEL

Lem onnier, and other astronomers in France and by f i Bode i n Germany. E forts were made to calculate ts on orbit, the assu mption that it actually was a cometary e body. Orbits were calculated by M chain , De Saron , and e Laplace, others . Th se efforts were fruitless . On 8 th May De Saron announced that the “ comet was much more distant from the Sun than had been supposed . Laplace independently reached a similar conclusion . Meanwhile, Lexell , the St . Petersburg n the mathematician , who happened to be in Engla d when discovery was made, informed the St. Petersburg Acad emy that the Object discovered by the Bath musician was probably not a comet at all , but an exterior planet , revolving at twice the distance Of Saturn , thus confirming ’ e Maskelyne s sagacious surmise . Later it transpir d that the planet had been observed n o fewer than sevente en times between 1 69 0 and 1 78 1 by able observers such as o Flamsteed , Bradley, Lemonnier, and Meyer, all of wh m ff failed to di erentiate it from an ordinary star, either i n

e or its . r gard to its appearance motion Lemonnier , indeed , had the discovery almost within his grasp, for b o n i h he o served the planet four consecutive days . 1 6 e O f J anuary, 7 9 , but his carelessn ss robbed him the distinction o f detecting a new celestial body . ’ N 0 little excitement was aroused by Herschel s achieve ment . It was the first planetary discovery within the o f — memory man Mercury, Venus , Mars, J upiter, and

Saturn having been k nown from prehistoric tim e s . the n ot More wonderful still , discovery had been made, u n by the leading astronomers of the day, but by an At o n e e kn o wn amateur. bound Herschel l aped from o f o n Obscurity to fame . The Royal Society L ndo 1 8 1 awarded hi m the Copley Medal in November, 7 , and b e elected hi m a Fellow in Decem er, ex mpting him from

f as . payment o subscriptions, a mark of esteem The s o n discovery had caused a stir in still higher circle , and th Ma 1 8 2 was f t 1 0 y, 7 , Herschel in ormed tha the King H ERSCHEL A s AMATEUR ASTRONOMER 2 3

— t o George I II expected make his acquaintance. On h to 8t . May he left Bath join his friend , D r Watson, at ’ Lincoln s Inn Fields, taking with him his instruments , - to star catalogues , maps , tables, etc . In a letter his 2 th sister, dated 5 May, he stated that he had had an c to audien e Of the King, whom he presented a drawing o f nd the Solar System . On 2 July Herschel noted i n his diary : I had the honour Of showi n g the Ki n g and "ueen and the Royal Family the planets Jupiter and

Saturn , and other Objects Herschel was now seriously considering the possibility O f abandoning the profe ssion o f music and devoting to himself astronomy . There can be little doubt that after George I I I expressed interest in the discovery, Herschel indicated that he was anxious to be made “ independent O f music The result Of his interview ’ with the King was his appointment as King s Astronomer . The appointment is referred to by Herschel himself in “ his journal in the following terms : It was settled by H is Majesty that I should give up my musical profession and , settling somewhere in the neighbourhood of Windsor, ” t o devote my time to astronomy . The salary attached ' — the new ofll ce was fixed at £ 200 certainly n o t a large ’ sum . . Indeed , when Herschel s intimate friend , Dr as to Watson , was informed the exact amount, he e e s o xclaim d , Never bought monarch honour cheap n to 1 8 2 Writi g her nephew , Sir John Herschel , in April , 7 , Caroline attributed the close bargains ” made between “ George I I I and her brother to the shabby, mean ” f spirited advisers o the King . Undoubtedly H erschel f made a pecuniary sacrifice in accepting the Of er, but of o n o f the prospect entering again the toils teaching , ” “ hi s u s etc, sister tells , which awaited my brother at ” o f home, appeared to him an intolerable waste time . Doubtless Herschel believed it t o be the best policy t o ’ close with the King s Offe r and thus be free to devote himself to the study whi ch had become the master 2 4 HERSCHEL

f l passion Of hi s life. The meagreness o the a lowance re has been Often commented upon , but it must be e the memb red , in justice to George I I I , that , firstly, purchasing power of money was considerably greater then than now, and, secondly, the regular duties attached to ffi n o the O ce were at that time very few . There is o f doubt that George I I I , by his creation this new post, ’ made possible Herschel s long career o f investigation : for and discovery no man , not even Herschel, could possibly have stood the strain o f a life o f professional on e activity .and scientific investigation combined . As O f “ O f his biographers has well said, The astronomer ” Slough was the gift to science o f the poor mad ki ng .

2 6 HERSCHEL prompted H erschel in his choice of a name for the new planet which he had discovered . A s 1 8 2 — a early as May, 7 before the King had p ’ — pointed him as King s Astronomer Herschel was ap parently o f opinion that the ne w planet should be named

. l oth after George I II In a letter to Herschel , dated 1 8 2 C May, 7 , Colonel Walsh, evidently one in lose touch : w ha d with the court , wrote In a conversation hich I the o n h e honour to hold with His Majesty 3 ot ult. conc rn o f n ew ing you and your memorable discovery a planet, I took occasion to mention that yo u had a two - fold clai m as a native O f Hanover and a resident o f Great the was be Britain , where discovery made, to permitted ” to name the planet from His Majesty . In a letter to his friend Watson i n July, H erschel suggested the name, ” e r i m G o nu . Sidus g It was not until the following year, after he was settled at Datchet , that Herschel addressed n to Sir Joseph Banks , Preside t of the Royal Society, “ o f a letter concerning the name the new planet . In ” the o f e fabulous ages ancient times , he said in the cours o f e the n o f e this lett r, appellatio s M rcu ry, Venus, Mars , e as Jupit r , and Saturn were given to the planets being f the names O their principal heroes and divinities . I n hardl be the present more philosophical era , it would y allowable t o have recourse to the same method and to o n o r M e fo r call Juno, Pallas, Apollo in rva a name to o r u new heavenly body. The first consideration in any particular event o r remarkable incident seems t o be its : e be chronology i f, in any futur age, it should asked when - e w a s e e this last found plan t discov r d , it would ‘ to s a e o f be a very satisfactory answer y, I n the r ign ’ e King George the Third . As a philosopher, th n , the name of Geo rgium Sidus presen ts itself to me as an appellation which will conveniently convey the inform a tion o f the time and c ountry where and when it was e e to e brought to vi w . Hersch l then proceeds ulogise “ the King as the li beral protector of every art and AS P ROFESSIONAL ASTRONOMER 2 7

own science , and as his benefactor , and closes with “ : ou as these words By addressing this letter to y , Sir , of f President the Royal Society, I take the most ef ectual method o f communicating that name to the Literati o f e e Europe, which I hope they will rec iv with pleasure ’ e Herschel s sugg stion, however , did not meet with the of e A s approval the sci ntific world . the late Sir Robert

Ball happily expressed it, the continental astronomers thought that the King Of England would “ seem Oddly associated with Jupiter and Saturn ; perhaps also they on considered that the British dominions , which the Sun e e nev r sets, were already quite large nough without ” further extension to the celestial regions . Lalande O f fo r proposed the name H erschel , and a considerable time the planet was thus known in France. Indeed the name was also adopted in many circles in Great Britain . “ o f o f Bode Berlin , the editor the Astronomisches Jahrbuch o f the day and o ne Of the leading German “ ” astronomers , suggested Uranus, in keeping with the o ld custom o f affixing mythological names to the celestial

Fo r e . bodies . years all thr e names were in use In the ” ” a “ Nautic l Almanac the name, the Georgian , evi ” dentl y preferred to Georgium S idus, was used ‘ Ofli ci all 1 8 the o f y until 47 . By middle the century, how “ l ever , the name Uranus had been general y adopted , and there can be no doubt that the decision was sound .

Bode was right and Herschel wrong. We can hardly suppress a feeling o f regret that

Herschel , with his great mind and soul , could have made a suggestion which savoured o f sycophancy : but we NO must bear in mind the circumstances . planetary discoveries had been made since prehistoric times, and there was something to be said for making a new depar ’ e ture. That Herschel s suggestion was not mad solely o u t o f gratitude is Obvious from the fact that he had practically decided o n the name before he was appointed he n f o w . s t t e O fice As a m atter of fact, Herschel seem 2 8 HERSCHEL to have undoubtedly had for the King a high personal regard . They were both Hanoverians, and thus there was a sentimental tie between them : and George I I I . , whatever condemnation we may pass on him as a mo n arch , seems undoubtedly to have taken an intelligent e interest in astronomy. In his early days he had mad observations at the private observatory at Kew. That he did take an intelligent interest is Obvious from a lette r 2 0th 1 8 f which H erschel wrote on May, 7 7 , to an O ficial at Windsor Castle, i n which he requested him to inform O f the King the luminosity of a lunar crater , adding that he would himsel f be at Windsor in the evening to s ee the ’ I - s t fo r e King s o foot telescope e up obs rvation . Despite Herschel ’ s own friendship for the King and his own Of silence as to the smallness his salary, there can be no doubt that he was at first sorely handicapped by n straitened circumsta ces . He had made a great financial ’ sacrifice in accepting the post of King s Astronomer.

Had he been able to avoid incurring expenses , he could have managed to live on 200 a year but it was impera the tive for him to construct larger instru ments , and i nstruments which he had were in constan t need o f repair has and readj ustment. His salary, as been well said by “ of the late Miss Clerke , gave him the means living, but ” not of observing as he proposed to Observe . Accord i ngly he plunged with enthusiasm into the work O f “ making telescopes for sale . The goodness of my ” telescopes , he wrote in his journal , being already fo r known, I was desired by the King to get some made those who wished to have them . This business in n o t e e the end only proved v ry lucrative, but also enabl d me to mak e e xtensive experiments for polishing mirrors ” by machinery . - H e r Despite the strenuous work of telescope making, o f schel , while at Datchet, continued his nightly surveys f sk . H is o the y third review the heavens , which had

w s i n . anu ar e m d B t , a , b en com ence at a h completed J. y AS PRO FESSIONAL ASTRO N O MER 29

' 1 l amsteed s 784 . This review included all the stars Of F catalogue and the small stars near them . The work was ob carried through with amazing rapidity. He would for o r as serve ten twelve hours at a stretch , and many as 400 stars were Observed and measured in the course of e n a night . Lat r in the same year, his atte tion was drawn to star-clusters and nebulae by the appearance o f ’ 2 8 th Messier s famous catalogue, and accordingly on “ 1 8 e e for October, 7 3 , he b gan to sweep the heav ns the se Objects with his new 20 - foot re flector o f 1 8 7 inche s to O f aperture, and at the same time gauge the depth e O bser the sid real system . A number Of experimental vat ion s o n 1 8th were made, and December he com “ menced w his systematic s eeps, which were continued

t Hl I 80 2 .

In this work he found his Sister an invaluable helper . “ 1 8 2 she e I n 7 tells us , her thoughts w re anything but cheerful I found I was to be trained as an assistant astronomer, and by way Of encouragement , a telescope ‘ ’ fo r o f two adapted sweeping, consisting a tube with ’ as glasses, such are commonly used in a finder was ‘ ’ w s t o for . given me . I a sweep comets But it was not until the last t wo 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 n n without a huma bei g near enough to be within call . All these troubles were re moved when I kn ew my brother to be at no great distance making observations with his

on . various instruments, double stars , p lanets, etc , and I could have his assistance immediately when I found a or o f o f nebula , cluster stars , which I intended to give a catalogue but at the end o f 1 78 3 I had only marked was fourteen, when my sweeping interrupted by being employed to write down my brother ’ s Observations with ” ’ the large 2 0- foot Caroline s observations are preserved o f o b in three volumes of quarto and four folio . These servati ons not were at first unattended by danger . They 3 0 HE RSC H EL were commenced wh en the mountings o f the telescopes el e were in a very unfinished state, and Herschel was vated fi fteen feet o r more o n a temporary cross - beam ” e me instead Of a safe gallery . Caroline H rschel herself t the 1 8 with a somewhat severe accident on last day of 7 3 , and she left it o n record that the Italian astronomer Pi az zi fl discoverer O f the first asteroid did not go home without getting broken shins by falling over the rack - bar o f 1 8 ol d By the summer 7 5 , Herschel decided that the house at Datchet was impossible as a permanent resi a be dence . An attack O f gue was found to due to its i n damp situation . Accordingly, early June, the Her schel s e e r moved to a house at Clay Hall , n ar Old Windsor, e e e e wher Observations w r at once commenc d . But — “ trouble arose with the landlady a litigious woman — who refused to be bound to reasonabl e terms and in the following spring H e rschel fixed upon a ne w hom e at n a Slough, near Windsor . Thither his instrume ts and p n o n rd 1 8 6 the paratus were tra sported 3 April , 7 , without ’ “ o o f l ss a single hour s Observation . The last night at ” “ e Clay H all , says Carolin , was spent in sweeping till daylight and by the next evening the telescope stood ready ”

l . for observation at Slough . This was the ast removal ’ The remainder of Herschel s life was spent at Slough “ the the spot Of all the world , said Arago , where ” greatest number O f discoveries have bee n mad e Here for many years , Herschel and his devoted sister worked fo r e from twilight to dawn , sweeping clusters and nebula , e e counting the stars in limit d regions Of the h avens , he n occasionally scrutinising the Moon and t pla ets . If ” “ no t e for n o f it had been , writ s Caroline , the interve tion o r a cloudy or moonlit night , I know not when he I ” e an e t oo either would hav got y sleep . In the daytim , , t o t o his activity was ceaseless . H e had attend his tele scopes and to direct the army O f workmen who were o e r a i n d c nstantly mployed making ep irs ad ition , he was AS PRO FESSIO NAL ASTRONOMER 3 1 actively employed systematising hi s Observations and co ordinating his results , which appeared in the long series “ o f papers contributed to the Philosophical T ran sac ” — tions o f the Royal Society collected and published in 2 two volumes i n 1 9 1 . I t soon became apparent that the work O f making fo r telescopes other observers, though lucrative, was in co n many respects a waste of time. H erschel had long tem l ated e p the construction of a v ry large telescope, but this was impossible so long as his spare time was given O f to the manufacture smaller instruments , the great majority Of which passed into t he possession o f royal or aristocratic dabblers in astronomy and were practically mere ornaments. A few, however, were supplied to - S chrOter continental astronomers . With a 7 foot , , the

German astronomer, practically inaugurated the system ’ atic stu dy o f the Moon s surface. Caroline Herschel notes that it was her brother’ s chief object at this time to construct a 3 0 o r 40 - foot i n st ru “ w - fi ve ment , for he was then on the rong side Of forty and felt how great an injustice he would be doing to himself and to the cause of astronomy by giving " p hi s time t o making telescopes for othe r Observe rs But nothing could be done without a grant from the King ; Herschel could n ot bear the expense of constructing a fo r great telescope himsel f. After some preliminary spade - work had been done in the proper quarters by his

- life long friend, Sir William Watson , Herschel requested O f e Sir Joseph Banks, President the Royal Society, to mak application for a grant from the King. In September, 1 8 o f 2 000 7 5 , a grant £ was made, and preparations for the making Of the instrument were at once begun . Two su m o f 2 000 years later a second £ was granted , and in his addition H erschel received, over and above salary , £2 00 per annum for the up keep Of the telescope ; while a salary Of £5 0 a year was bestowed o n Caroline Herschel ’ n as her brother s assista t. By this time her name was 3 2 HERSCHEL

e I st b coming famous in the world of science. O n August, ’ 1 86 s he 7 , during Herschel s absence in Germany, dis v a co ered comet, the first Of eight similar Objects to her credit . The small annuity conferred upon her was a — — recognition painfully inadequate Of her own work in astronomical science . The construction Of the great telescope l occupied i nst ru nearly four years . The erection O f this immense f ’ ment took up a great deal O Herschel s attention . His “ sister asserted that the re is n o t on e screwbol t about the whole apparatus but what was fixed under the i m O f mediate eye my brother. I have seen him lie stretched u n many an hour in a burning s , across the top beam while the iron - work for the various motions was being

- fixed . At one time , no fewer than twenty four men (twelve and twelve relieving each other) kept polishing day and night ; my brother, O f course, never leaving them all the while, taking his food without allowing ” s it himself time to down to table . e This ceas less industry bore fruit when in August , ’ 1 8 u se 7 9 , the great telescope was ready for . Herschel s t former telescopes had been New onians , with small 8 secondary mirrors . I n January , 1 7 7 , however , he

- made a novel experiment with his 2 0 foot telescope . e n In order to sav the light lost by the second reflectio , Herschel removed the small mirror and slightly tilted the tube. The result more than j ustified ex pectations , and the experiment resulted in the discovery of two e to satellites Of Uranus . Accordingly, he d cided make ” - - the 40 foot telescope on this front view principle . This particular form of the reflector i s known as t he

Herschel ian . Herschel was very proud Of his large telescope and

in 1 79 5 sent a description Of it to the Royal Society.

on . Yet, the whole, its performances were disappointing I mmediately it was erected Herschel succeeded in co n

3 4 H ERSCHE L be n o doubt either that the marriage was a very happy one a , and th t the relations between his wife and his sister were all that could be desired . From this time o onwards , however, Caroline Herschel resided in l dgings o f in the village Slough .

In the earlier part of his career, Herschel rarely went rd 1 86 from home except on business . On 3 July, 7 , hi s e accompanied by brother Alexand r, he started for o O f G ttingen , in order to convey to the University one his 1 0 - foot reflectors as a gift from George I I I . This

to . In 1 2 was his last visit his native country 79 , he n made an extensive tour in E gland and Scotland , in the o f K omarzewski company a Polish friend , General . Visits were paid to the principal factories in the middle O f and north England , and Herschel Seems to have taken a 7 - foot telescope with him in order to treat his hosts to

. C views of the heavens The tour embraced oventry, — — Birmingham where he dined with James Watt Bangor, o Carnarvon , and Manchester, then via Liverpool , Prest n ee and Carlisle to Glasgow. Here he received the fr dom o f Of the city and the degree LL . D . from the University . to From Glasgow the friends proceeded Edinburgh , from whose University Herschel had received the same degree si x years earlier . In Edinburgh he met numerous liter o ary and scientific men, including Principal Roberts n O h and Dr . H utton , and , in addition , inspected the s erv ato r was y . The return journey made by Sunderland ,

Durham and Richmond in Yorkshire .

At the close of the eighteenth century, Herschel was at the zenith of his powers and at the height Of his on prosperity. Honorary degrees were c ferred upon him and learned societies enrolled his name among their members . He accepted these recognitions of his genius , who but put little stress upon them . Miss Burney, along with her father visited him on numerous occasions, H “ described erschel as perfectly unassuming, yet Openly A S PRO FESS ION AL ASTRO N O ME R 3 5

happy, and happy in the success Of those studies which would render a mind less excellently formed presu mptu not o u s and arrogant. The King has a happier subject than this man . He seems a man without a wish ” i ts the err strial that has Object in .t e globe. C HAPTER IV.

S L AND PL T S T" D S O AR ANE ARY IE .

’ O NE result O f Herschel s fame as the founder Of stellar astronomy has been that his greatness as an Obse rver and student O f the Sun and planets has been large ly v overlooked . Ne ertheless his work in solar and planet ary astronomy alone would have gained for him the highest position among the astronomical Obs ervers O f the " “ ” . 1 day Among the celestial bodies , he wrote in 79 9 , the Sun is certainly the first which should attract our ” notice. From an early date he was attracted by solar phenomena , and in the course of his career contributed e o n s veral papers the Sun to the Royal Society. I n the “ o f first these , On the N ature and Construction Of the 1 8 th 1 Sun and Fixed Stars , read December, 79 4 , he pro ’ O f n pounded his hypothesis the Su s constitution, to which he adhe red throughout his lifetime. ’ Before Herschel s time, the Sun had been Observed by e e Galil o , Schein r, Fabricius, Hevelius , Cassini and others . Sun - spots had been Observed for over a century and a half and many i mportant details had been detected, but concerning their nature controversy had raged and u n

e . 1 c rtainty prevailed In 7 74, just at the beginning Of ’ e - e H rschel s career as an Observer, the well known th ory su n - o n Of sp ts was propounded by Alexander Wilso , O f Professor Astronomy in the University of Glasgow . A serie s o f Observations convinced him that the spots were depressions beneath the general surface o f the Sun ; n not mountains , as ma y Observers had supposed , but cavities in the glowing surface through which the darker (3 6) SOLAR AN D PLAN ETARY STUD IES 3 7

e interior was visible . Is it not reasonable , he ask d , “ to think that the great and stupendous body o f the Sun O f ff is made up Of two kinds matter, very di erent in their qualities : that by far the greater part is solid and dark and that this immense and dark globe i s e n compassed with a thin cove ring of that resplendent substance fro m which the Sun would seem to derive the whole o f his ” ’ revivi fying heat and energy ? Herschel s earli est O b ’ serva t i o ns were confirmatory o f Wilson s conclusions . 1 8 I n 7 3 he closely followed a large spot, noticing that it was plainly depre ssed below the surface o f the Sun ” and that it had very broad shelvi n g sides He was ’ o o f s on led to adopt Wilson s view the solar constitution , which he developed i n his first paper o n the Sun in I 79 4 H is Observations of the great spot o f 1 774 led him t o conclude that he viewed “ the real solid body Of the Sun see i ts n at itself, Of which we rarely more than shini g ” mo sphe re This interpretation o f su n - spot Obse rvations

- e H e was the foundation stone of his theoretical edific . e o f concluded , in agreement with , but independ ntly , su r Wilson , that the solar globe was dark and solid , rounded by a glowing atmosphere com posed o f various ” elastic fluids that are more or less lucid and transparent . S chrOter This lucid fluid , named by the photosphere, Herschel believed to be generated in the Sun’ s atmos h re e . he p An analogy, said, might be drawn from the o f e generation clouds in the terrestrial atmospher . I n o f 1 80 1 e are his paper , Herschel concluded that ther two ff o f di erent regions solar clouds, like those upon our In re globe. that case their light is only the uni form ” flection - Of the surrounding superior self luminous region . “ The solid body Of the Sun beneath these clouds, “ Herschel said, appears to be nothing else than a very o r eminent , large and lucid planet, evidently the first , in one o f our strictness Of speaking, the only primary t o systems ; all others being truly secondary it . This 3 8 HERSCHEL

solid body, he believed to be protected from the great heat of the elastic fluid o f its o wn atmosphere by dense planetary clouds ; it was diversified by mountains and valleys, and was in every way analagous to the Earth and ”

. he the other planets We need not hesitate to admit, “ 1 i s i nhabi said in 7 94 , that the Sun richly stored with ”

. 1 80 1 he tants In , after further close study, claimed e that all his former arguments had be n confirmed . ’ Herschel s theory met with general acceptance fo r a many years . It h r monised with the trend Of later — eighteenth century thought , which possibly as a result Of the reaction from narrow theologica l views Of the Earth’ s supreme place in nature— shrank from the idea of empty worlds . It was not until the invention Of the spectroscope that the theory was universally abandoned . w as Untenable though it was, it the first serious attempt to co - ordinate the isolated facts ascertained concerning phenomena Of the solar disc . The fallacious nature of his theory should not blind us ’ to Herschel s great work as an Observer of solar phe n m n o f o e a. In his paper Of I 79 4 he noted the existence “ ” elevated bright places which , after H evelius, he named “ faculae . I see these faculae extended over about e - o f o n sixth part the Sun . Towards the north and south I see no faculae ; there is all over the Sun a great e O f unevenness in the surface, which has the appearanc a mixture O f small points O f an unequal light ; but they are evidently an unevenness or roughness of high and ” fe w f low parts . Very details O the solar surface escaped o f 1 8 0 1 his persistent scrutiny. H is paper described the process o f spot- formation with a wonderful accuracy of e— detail . Curiously enough , Hersch l although h—e devoted attention to the prevalence or absence of spots failed to

su n- notice the spot period . Probably he would have done

t o . so, had his attention the Sun been more exclusive ’ Herschel s solar work was not purely telescopic . H is investigations on light and heat occupied a great deal Of S OLAR AND PLANETA R" STUD IE S 39 his time at the beginning O f the century ; and he con tributed to the Royal Society on these s ubjects four was papers in rapid succession . He led to the inquiry by his Search for the most suitable dark glasses for solar o f s observation , in the course which he found that ome materials were opaque to light and others to heat. H is papers have been called the first exposition worth ” mentioning of the principles Of radiant heat . I n this exposition he showed that radiant heat obeyed the laws

Ofreflection , refraction and dispersion . H is investigation of the infra - red heat rays led to one of his greatest di s — coveri es that O f the invisible portions of the solar spec trum .

Early in his career, Herschel paid considerable atten H i s 1 80 w tion to the Moon . second paper i n 7 dealt ith his measures Of the height o f the lunar mountains . In I 7 8 3 a sensation was caused in scientific circles by the news that Herschel had seen lunar volcanoes i n violent eruption . In a letter to Magellan , a Portuguese amateur “ on th astronomer , he stated that 4 May, he perceived in the dark part of the Moon a lu minous spot. It had the appearance of a red star Of about the fourth magni ” 1 8 tude . I n 7 7 he communicated a paper to the Royal of Society, i n which he announced the appearance other three volcanoes , and in which he promised the Society an th 1 8 account of the eruption of 4 May, 7 3 . This account was never forthcoming . The leadi ng French astronomers were inclined to the view that the appearances were

- actually due to earth shine . It is possible that Lalande , 1 8 8 who visited Slough in 7 , may have converted Herschel was to this view . At all events , nothing further published concerning the supposed volcanoes . Herschel believed the Moon to be both habitable and e 1 inhabit d . Yet he laid it down in 79 4 that we per cei ve its no large seas in the Moon , that atmosphere (the existence O f which has even been doubted by many) is extremely rare and unfit for the purposes Of animal HE R SCHEL

life ; that its climates , its seasons, and the length of its days totally differ from ours that without dense clouds (which the Moon has not) there can b e no rain ; perhaps ” n o rivers, no lakes . H is belief in the habitability Of our “ satellite arose from the view that its inhabitants are fitted to their conditions as well as we on this globe are to ours e O f the planets , Mercu ry alon was neglected by Herschel ; he studied it only when i n transit across the “ ” o n — an solar disc . H is Observations Venus object , “ e he said , that has long ngaged my particular attention — e 1 were commenc d in April , 777 , and were continued for — sixteen years . Herschel had four Objects in view to o f measure the rotation period the planet, to ascertain e e the presence or absenc Of an atmosphere , to determin ’ “ e the e an d accurat ly planet s diamet r, to give attention to the construction o f the planet with regard to perma ” nent appearances . He satisfied himself that Venus did o n o f rotate, but the diurnal motion , he said , account o f o f the density the atmosphere this planet, has still e eluded my constant attention , as far as conc rns its ” period and direction . The spots which Herschel dis ’ o e - defi ned c vered on the planet s surface w re faint and ill . His Observations on Venus we re in direct contradiction chrOter n o t to those of S . The German astronomer had ’ o 2 7 only estimated the planet s rotati n period at 3 } hours , on but had announced the existence Of mountains Venus , whose height exceeded fi ve or Six times the perpendi cu

el i ‘ f A s o lar evat on o Chimborazo . to the mountains n ” “ e sa V nus , said Herschel, I may venture to y that no n e o r eye which is not co sid rably better than mine , e assisted by much b tter instruments , will ever get a sight ’ e on Of them . Hersch l s negative conclusions have been the whole confirmed by later astronomers . Herschel may be safely called the founder o f Martian 1 on astronomy. I n 777 he commenced Observations “ Mars, and he early satisfied himsel f that the constant

42 H ERSCHEL

Of the atmospheric condition Of Jupiter what has been ” “ as - known the trade wind theory . As the pri ncipal o n we e belts Jupiter are equatorial , and as have c rtain e constant winds upon our planet that regularly, for c rtain

‘ periods , blow the same way, it is easily supposed that they may form equatorial belts by gathering together the vapours which swim in ou r atmosphere and carrying them about in the same direction . This will by analogy ’ ” O f account for all the irregularities Jupiter s revolutions . e e 1 Herschel d vot d no other paper to Jupiter, but in 79 7 “ he communicated to the Royal Society hi s Observa e o f tions Of the Satellites Of Jupiter, with a D termination

‘ their Rotation From his determinations O f their vari the o f able brightness, he concluded that rotation periods all four satellites coincided with their periods of revol u — tion round Jupiter a conclusion confirmed by s u bse quent research. Herschel also made the first attempt a to me sure the diameters of the satellites . H is conclu — — sion also confirmed by later observers was that the third satellite is considerably larger than any Of the rest ; that the first is a little larger than the second and nearly Of the size of the fourth and that the second is a little smaller than the first or fou rth or the smallest O f them ” all . “ The planet Saturn , Herschel wrote, is perhaps on e O f the most en gaging objects that astronomy Offers ou r A S to view . such it drew my attention as early as ’ e the year 1 774. And it received more of Hersch l s e attention than any Of the other plan ts . Six of his papers n 1 8 to the Royal Society dealt with Satur , the first in 7 9 1 8 and the last in 1 8 0 5 . He concluded in 7 9 that the planet had an atmosphere o f c onsiderable density ; and from the appearance o f the belts he i nferred that it

turns upon an axis which is perpendicular to the ring, and this view was confirmed by his detection of a con iderabl e n 1 s polar flatteni g . In December, 79 3 , he stated “ that the period o f rotation is probably not o f a long S OLAR A ND PLANETARY ST"DIES 43 duration and in the following year he confirmed his 1 0 suspicion , and announced the period of rotation as o 6 h urs 1 minutes . Five satellites Of Saturn were known when Herschel o f commenced his study the planet . H is discovery of two exceedingly faint inner satellites, rendered fainter still by their proximity to the bright disc and ri ng of o f Saturn , was the result long and continued investiga “ ” tion . He had entertained strong suspicions Of the existence o f a sixth satellite fo r a considerable time ; o n 1 1 8 n 2 0 - as and 9 th August, 7 7 , usi g the foot reflector “ ” e a front vi w , he noticed an object which he marked a The down s possibly a sixth moon . possibility was on 2 8th 1 8 rendered a certainty when August , 7 9 , he

n 0 - o n tur ed the new 4 foot Saturn . Six satellites were ’ a m nifestly visible , sharing in the planet s motion . On 1 7 th September , he detected another satellite, still fainter, and closer to the ring, revolving in less than one terrestrial day. These moons were named Enceladus o e the and Mi mas . Two years later he ann unc d that — — fifth satellite Japetus performs its rotation , like the o f o u r moons Jupiter and moon , in a period coincident to with its revolution , These conclusions led him an “ m important generalisation , that a certain unifor plan is carried o n among the secondaries o f our solar system ; and we may conjecture that probably most of the moons ” Of all the planets are governed by the same law .

- 1 8 The ring system fascinated Herschel . In 7 9 he e t wo susp cted its division into , and this suspicion was “ 1 1 u n confirmed in 79 . Its division into two very ” equal parts can admit of no doubt. He appears to have “ o r n ot seen the inner dusky crape ring, but he did recognise it as a portion of the system . I n common with Laplace and contemporary astronomers, he believed to 1 8 1 the rings be solid structures . In August, 5 , e H erschel made his last obs rvations Of the planet, with

0- 2 - both the 4 foot and the 0 foot telescopes . 44 HERSCHEL

e the e As was to be xpected , plan t Uranus was an e 1 8 Object of special inter st to its discoverer. In 7 3 he communicated the results o f his preliminary study o f the H e e e new planet to the Royal Society . th n stimated that “ the real diamete r Of the planet must be between four the and five times that Of Earth I n a later paper, in 1 88 n 7 , he annou ced the diameter as miles o n a remarkably accurate measure. He c mme ced soon e e A t after the discovery to search for Uranian sat llit s. first he was c o ntinually disappointed and gave over the attempt . Resuming his Observations , however, with the

- e o n 1 1 th 1 8 front view m thod, he detected January , 7 7 , two very faint stars . After careful search of these Objects in motion he tells us that he deferred a final judgment “ as to the ir nature till l oth February. And in order to of t wo e e put my theory these sat llites to a trial , I mad a sketch o n paper to po int o u t beforehand the ir situation o with respect to the pla n et and its parallel of d eclinati n .

n - e o n n ot withstan d The lo g exp cted evening came , and ing the most unfavourable appearance Of dark weather, it e e the clear d up at last , and the heavens now display d original o f my drawing by showing i n the situation I e we Geor i a n l a net a ttended é tw o had delineated th m , g p y ” l l i tes sa te . He determined the times O f revolution Of these moons estimated their size as probably not less than that o f the satellites o f Jupiter ; and noted the great i n clination of 1 their orbits . In 79 7 Herschel announced the discovery o f four additional satellites , but this was never confirmed , and there ca n be littl e doubt that what he actually O h served we re small faint stars ; although it is just po ssible that he may have glimpsed the very faint inner pair de tected 1 8 in 47 . A suspicion that Uranus was encircled by a ring S imilar to Saturn was finally negatived by hi s 1 2 “ investigations in 79 , which he described as very de ” ci s ive against the existence Of a ring . o f Herschel never discovered a comet . This branch SOLAR A ND P LAN ETARY STUD I ES 4 5

who astronomy he left to his Sister, detected no fewer o f n than eight during the course her Observi g career . I st 1 86 The first Of these, discovered August, 7 , was the O f o subject a short com munication t the Royal Society. too to Other comets , , seem have been closely studied by 1 8 1 1 him . The great comet Of called forth a long com

un ication . m to the Royal Society In this paper , he n emphasised the transie t nature Of comets .

Herschel missed discovering the first four asteroids, which were detected by Piazzi , Olbers and Harding, when the great astronomer Of Slough was at the height Of his powers as an Observer . He closely studied them after their discovery and endeavoured to measure their discs, hi s n ot but measures were very exact . In a paper “ o n on read before the Royal Society, Observations the ” two lately discovered celestial bodies , he suggested the “ ” ne w name asteroids for the worlds . Brougham in “ ” to the Edinburgh Review took exception the name, and insinuated that Herschel had deliberately coined it for the purpose o f keeping the discoveries o f Piazzi and o n own of Olbers a lower level than his discovery Uranus, o o Herschel made n direct reply t the attack . He merely referred to the fact that he had “ incurred the illiberal ’ o f 1 80 criticism the Edinburgh Review, and in 4 , in a on e subsequent paper the asteroids , after the discov ry Of

Juno , he said that the specific difference between planets and asteroids appears now, by the addition Of a third O f to f individual the latter species, be more ully estab li shed , and that circu mstance , in my opinion , has added more to the ornament Of o u r system than the discovery ” Of another planet could have done . CHAPTER V .

T H E S T T OF THE V CON R " C ION HEA EN S .

K WL DG of A NO E E Of the construction the heavens , 1 8 1 1 Herschel wrote in , has always been the ultimate of Object my Observations . All his other investigations

- — solar, planetary and stellar were secondary to this o f great aim . Before the commencement hi s career as an astronomer, the stars attracted very little attention .

- n Star catalogues had been formed , but , evertheless, the stars were regarded chiefly as convenient reference- points for observations Of the Moon and planets . A few doubl e and variable stars and several star- clusters and nebulae had been discovered theories of stellar distribution had been outlined by one or two Obscure non - professional astronomers, such as Wright and Lambert . But there was little interest among astronomers in the study o f the stars for their own sakes ; and no great systematic eff ort had been made to discover the laws Of stellar di st ri bu tion and motion . of was The field sidereal astronomy, therefore, virtu o f ally untrodden when , shortly after the beginning his hi s o f telescopic work , Herschel began first review the 1 i n heavens. H is second review , commenced in 779 ,

- cluded stars down to the eighth magnitude. By products of this review were the discovery o f Uranus and the formation Of his first catalogue Of double stars . In 1 8 1 b e e Dece mber, 7 , commenced his third r view , which 1 8 he completed in January, 7 4 , and which resulted in the

- publi cati on O f a second double star catalogue . The prob (46) TH E CO NSTRUCTION O F THE H EAVEN S 47 lem which confronted Herschel was two - fold : ( I ) the

an d 2 o f . scale, ( ) the structure the stellar system I n 1 7 8 1 he had written a pape r on the parallaxes Of the n fixed stars , but his investigation only yielded a egative on o f result . Accordingly he concentrated the question the structure o f the universe and the arrangement Of its component parts . ’ In 1 7 8 3 the publication Of Messier s first catalogue ’ directed Herschel s attention to the star- clusters and A s a nebulae. soon as it came into his h nds , he says , he “ hi s 2 0 - saw applied feet reflector to the nebulae , and with the greatest pleasure that most Of the nebulae which I had an opportunity Of exami n ing in proper situations yielded to the force Of my light and power and were re ”

. n to solved into stars Accordi gly, H erschel decided “ sweep the heavens with two main Objects in view 2 to ( I ) to search systematically for new nebulae, and ( ) gauge the extent O f the sidereal system by counti n g the o f f of number stars visible in di ferent regions the heavens . 1 8 his on In 7 4 , in preliminary paper the construction Of

hi s of - the heavens , he described method star gauging, “ which , he said , consists in repeatedly tak ing the number of stars in ten fields of view o f my reflector very near n o n e each other, and by adding their sums and cutti g Off on of decimal the right, a mean Of the contents the Ob heavens , in all the parts which are thus gauged , is t ain ed

on The o O f I n his paper Constructi n the Heavens, I t 1 8 f i dated s January , 7 5 , Herschel gave the results O h s preliminary investigations and outlined hi s theory Of the “ ” “ . i s stellar system That the Milky Way, he said , a most extensive stratum of stars of various sizes admits no o f ou r i s longer the least doubt , and that Sun actually n i s one Of the heavenly bodies belo ging to it evident. I have now viewed and gauged this shining zone in almost o every direction, and find it comp sed Of stars whose o f number, by the account these gauges , constantly 48 HERSCHE L increases and decreases in proportion to its apparent ” brightness to the naked eye . I n the most crowded of a part the Gal xy, Herschel occasionally counted as 8 8 o f many as 5 stars in a field view, and in quarter of an ’ hour s time no fewer than 1 stars were thus enumerated , while other fields were almost destitute O f stars . Herschel made two important assumptions o f that the stars were, roughly speaking , the same size, and (2 ) that they were scattered throughout space with A s some approach to uniformity. a result of his star two gauges , he was enabled on these assumptions to estimate the possible extent and shape o f the sidereal system . He sketched it as a cloven disc Of irregular out e O f line , ext nding much further in the direction the

Milky Way than in that of the galactic poles , the cleft representing the famous division in the Milky Way . The Milky Way was regarded as more o r less an optical phenomenon, as a vastly extended portion Of the stellar e syst m . ’ Herschel s gauges led him to the view th at the galactic “ ” system was strictly limited in extent . It is true , he “ n ot to said, that it would be consistent confidently aflfirm that we were on an island unless we had actually e found ourselves ev rywhere bounded by the ocean , and therefore I will go no further than the gauges will author ise ; but considering the l ittle depth O f the stratum in all those places which have been actually gauged , to which must be added all the i n termediate parts that have been viewed and found to be much like the rest, there is but little room to expect a c o nnecti o n between ou r nebula ” and any of the neighbouring ones . The stellar system “ which he designated as o u r nebula was in his V iew an n island universe a very extensive branchi g, compound f ” congeries of many millions o stars . The majority Of nebul ae and clusters he believed to be independent stellar ae — fo r units . He divided these nebul , or milky ways at this time the two terms were interchangeable in hi s

5 0 HERS CHEL

as gave evidence Of age . Accordingly, he foresaw, a “ ” -u O f result of clustering power , the breaking p the a galactic system into many small independent nebul . More and more evidences of this “ clustering power ” came to his notice until in 1 8 0 2 he said Of the Galaxy “ This immense starry aggregation is by no means O f uniform . The stars which it is composed are very unequally scattered and show evident marks of cluster ” ing together into many separate allotments . H e was coming gradually to the view that the fundamental as

- — su mption underlying hi s disc theory that O f an average — equality of scattering was untenable . I n his paper of “ 1 8 1 1 he said : I must freely confess that by continu ing e o f of my sw eps the heavens, my Opinion the arrange ment of the stars and their magnitudes and Of some other particulars has undergone a gradual change ; and , o indeed , when the n velty of the subject is con sidered , we cannot be surprised that many things formerly taken on ff for granted should, examination , prove to be di erent from what they were generally but incautiously supposed

l ~ s n f . e u a catteri o to be For instance, an q g stars may be admitted in certain calculations ; but when we ex or - amine the Milky Way, the closely compressed clusters s o Of stars , of which my catalogues have recorded many instances , this supposed equality must be given up .

With the abandonment Of this general assumption, the

- disc theory became untenable. Herschel ’ s daring attempt to formulate a cosmology proved abortive. I n place Of this he was led to evolve a ’ of cosmogony . He appears to have been unaware Kant s nebular hypothesis ; indeed, he seems to have had, at his the beginning Of career, no conception of evolutionary development among the celestial bodies . The dim , misty - looking nebul a were all believed to be external e galaxies , which increased telescopic power could resolv

‘ into their component stars . He was led to question and then to reject this generalisation by his study Of a THE CONSTR"CTION O F THE HEAVENS 5 1 nebulous star of the eighth magnitude in the constellation

- Taurus , surrounded by a fai ntly lu minous atmosphere of o f considerable extent. The results his investigations and reflections were contained in his remarkabl e paper “ ” S O - I st On nebulous stars properly called, dated January ,

1 1 . to 79 In regard the nebulous star in Taurus, he said : Our judgment will be that the ne bulosity about n o t ou t the star is Of a starry nature I f, he pointed , o f the nebulosity consisted very remote stars , which “ appear nebulous on account Of great distance, then what must be the enormous Size o f the central point which outshines all the rest in so superlative a d egree as ” O f ? e to admit no comparison I f, howev r, the star i s e e Of average Siz , the small r points composing the nebu “ l osit y must be al most infinitesimal . We therefore n ot or either have a central body which is a star, have a star which is involved in a shining fluid Of a nature n o totally unk own t us . I can adopt no other sentiment than the latter . And with characteristic caution he “ added in the same paper : I f therefore this matter is

- self luminous , it seems more fit to produce a star by its condensation than to depend on the star for its exist ” ence . was 1 1 This in 79 , five years before Laplace suggested his classical hypothesis at the close Of the Systeme du ” e Monde The germ Of the nebular theory, therefor , e o f e was pr sent in the mind Hersch l at this early stage. of 1 1 e to In the paper 79 , Herschel proceed d apply his ne w view t o the various nebulous regions all ove r the too heavens . He concluded that he had been hasty in a his former surmise that all nebul were distant clusters . “ the I f shining fluid can exist without stars , we may with great facility explain that very extensive tel escopic “ nebulosity in the constellation Orion . What a field ” Of novelty is here opene d to ou r conceptions " In 1 802 Herschel dealt with the subject again in his Catalogue Of 5 00 new n e bul a But it was n ot till 5 2 H ERSCH EL

1 8 1 1 - , in another epoch making paper on the const ru ction of the heavens, that Herschel enunciated his nebular hypothesis . In this paper he gave a complete list o f a d nebul which he had discovered and studie , assorting them into as many classes as wi ll be required to produce the most gradual affinity between the individuals con ta i ned in any one class with those contained i n that which precedes and that which follows it Those co n t ai ned one in class and those in the next class in order , ff he declared, have not so much di erence between them , o wn in his suggestive remark , as there would be in an o f annual description the human figure, were it given from the birth O f a child till he comes to be a man in ” his prime . He traced the evolutionary sequence from f e l a extensive d i fus d nebulosities, through irregular nebu , ” “ e a a n bul a little brighter in the middle, nebul a ” e l ittle brighter and much bright r in the middle, a the nebul showing progress of condensation , planetary a e a a nebul and st llar nebul , to nebul nearly approach ing to the appearance o f stars He declared it highly “ probable that every succ e eding state Of the nebulous matte r is the result of the action o f gravitation upon it e o ne the whil in a foregoing , and by such steps successive conden sation o f it has been brought up to the planetary o n c ndition . From this the tra sit to the stellar form , it has been shown , requires but a very small additional ” o e o f e 1 8 1 c mpr ssion the n bulous matter. I n 4 he drew atte ntion to double nebul a joined by nebul o sity “ ” “ e e b tw en them . I t seems , he said , as if we had these double Objects in three di fferent successive con di ti o n s : first as n e bul a ; next as stars with remaini n g n e bul o sity ; and lastly as stars co mpl etely free from ’ nebulou s appearance H e rschel s nebular hypothesis has never received in text- books of astronomy the at e O f t ntion it deserves . It was the result long years Of o ne f patient study, and is Of the most per ect examples n o f o f i nductive re aso ing in the history science . TH E CON STRUCTION O F THE HEAV EN S 5 3

has Herschel , as been already remarked , had sought everthe a cosmology and he had found a cosmogony . N e l ss, he did not abandon his attempt to discover the

u . 1 8 1 1 8 1 8 str cture of the sidereal system I n 7 and , o f when nearly eighty years age, he communicated two remarkable papers to the Royal Society on the extent and condition of the Milky Way and on the relative distances Of clusters Of stars . In these papers Herschel

- explained his new method Of star gauging, which some writers have confused with his first . The two methods,

. o ne e however, were quite distinct I n the first , t lescope was used in different regi o ns of the h eavens ; whereas in u e e o n the second , vario s t l scopes were turned the same region . The new method assumed the distribution Of the stars to a pproximate to a certain properly- modified e o f r quality scattering , and also a certain equality Of eal o f 1 8 e brightness . I n the paper 1 7 he applied this n w 1 8 1 8 to principle to the Milky Way, and in the paper Of

- star clusters , assuming that the relative distances Of “ globular and other clusters can be d e termined by the e telescopic powers necessary to reveal and resolve th m , provided that the component stars are, generally speaking, 1 8 2 comparable to Sirius in size . Proctor, writing in 7 , “ contended that the principle is unso u nd and that Herschel himsel f would have abandoned it had he tested ” it earlier in his Observing career . Most writers have agreed with his estimate : yet recent work o n star 1 ’ clusters would seem to indicate that Herschel s second method was not so unsound as has been generally be li e d ve . Herschel propounded no hypothesis to take the o f - hi s place the disc theory . Indeed, later view was that the siderea l system was much more extended in the o f plane the Galaxy than he had previously believed . The utmost stretch of the space- penetrating power Of the 2 0- foot telescope could no t fathom the profundity O f ”

. 1 8 1 to the Milky Way In 7 , he gave expression the

1 B Dr. H a ow S a e at M o nt Wi son O se vator a o n a y rl h pl y, u l b r y, C lif r i , 5 4 HERSCHEL

“ su n view that not only our , but all the stars we can see with the eye a re deeply im mersed in the Milky Way O f and form a component part it Nevertheless , in the o f 1 8 1 8 ob paper , he held that some Of the nebulae, not v i o u sl y composed Of true nebulous matter, which he “ ” “ call ed ambiguous Objects are clusters of stars i n e disguis , on account of their being so deeply immersed i n space that none Of the gauging powers of o u r tele ” e to Ob scop s have hitherto been able reach them . v i ou sl e y, he still clung to the view that som of these “ ” e dim , misty Objects were island univers s . The paper o f 1 8 1 8 was the last which Hersch el wrote o n O f the the construction the heavens . He failed in o f e Object his search , but countless others hav failed a re since his day, and at the present time astronomers still groping after the solution Of the great problem . Herschel did not labour in vain : his papers o n the structure Of the universe form the foundation of all sub e sequent r search . I n the eloquent words of the late Miss Clerke : O n e cannot reflect without amazement that the special li fe - task set himself by this struggling — musician originally a p enniless deserter from the Hano — v eri an Guard was n o thing less than to search ou t the o f construction the heavens . He did not accomplish it , for that was impossible ; but he never relinquished it, founda and , in grappling with it, laid deep and sure the ” tions of sidereal science. CHAPTE R VI .

T S S ELLAR RES EARCHE .

HERSCHEL did not attain to the knowledge Of the ultimate structure Of the Universe to which he aspired but in the course Of his long career as an observer and thinker he was led to several discoveries o f the great

est . Of a was o f i mportance The discovery nebul , one of - of course, the Objects Of his long continued series “ ” his r sweeps o f the heavens . He com municated fi st catalogue Of 1 00 0 new nebul a and clusters o f stars to the Royal Society in 1 7 8 8 ; this was followed three 1 000 years later by a second catalogue Of similar objects, “ while in 1 802 he drew up a catalogue of 5 00 new a a C nebul , nebulous stars, planetary nebul and lusters ” of of stars . He was equally devoted to the study 1 double stars . These Objects , as already mentioned , first attracted his attention because o f their suitability for O f aral l a eS determination relative stellar p x . But Her schel soon realised that the measurement Of the annual parallax o f stars was beyond the power o f hi s i n st ru for the ments . H is quest parallaxes from study Of double stars led him to another discovery altogether . l oth 1 8 2 m On January, 7 , he com unicated to the o f 2 6 o f Royal Society a catalogue 9 double stars , which 2 2 7 had been discovered by himself ; this w as succeeded

of 1 8 . by a second list 4 3 4 in December , 7 4 From the to beginning of his study Of these stellar pairs , he seems as have had a suspicion to their nature . In the post “ : m n n script to his first catalogue he said In y opi io , it

a te IL 1 . Ch p r , p. 9 (5 5) 56 HERSCHEL is much too soon to form any theories O f small stars re ” o f volving round large ones It was , course, Obvious — that double stars might be optical only caused by two f n stars happening to lie in the same line o visio . Never thel ess o n , despite his caution , he kept a careful watch the relative positions o f the components Of double star systems for twenty years . In the paper accompanying o f 00 a I st 1 8 0 2 his catalogue 5 new nebul , read July, , “ Herschel expre ssed the view that casual situations will not account for the multiplied phenomena O f double ” e stars , and announced that he was about to communicat O f a series Observations , from which it would be evident that many Of them have actually changed their situation with regard to each other, in a progressive course, de noting a periodical revolution round each other ; and o f o f that the motion some them is direct , while that Of ” others i s retrograde . These Observations were tabu lated in two papers o n the Changes that have happened e e of e 1 8 0 in the r lativ situation double stars, r ad in 3

1 80 . and 4 respectively I n the first paper , Herschel brought forward evidence in regard to the orbital mo o o ti ns Of Alpha Gemin rum (Castor), Gamma Leonis , B ooti s " Epsilon , eta Herculis , Delta Serpentis , and e Gamma Virginis. The second paper gave d tails con o o n cerning ther fifty stars. Herschel als assig ed periods e i n to several Of the more prominent binaries . Thes vesti ati ons g , Herschel claimed , went to prove that many “ o e double stars are not merely d ubl in appearance , but must be allowed to be real binary combinations of two stars intimately held together by the bo nd Of mutual attraction The im portance o f the discove ry Of binary stars may be realised when we recollect that previously there was no scientific proof o f the prevalence O f the law of gravita

O f . tion outside the Solar System There were, Of course, strong reasons for believing the law to be universal and M man e John ichell , a Of r markable sagacity, had argued

5 8 HERSCHEL

o f far into a single real motion the Solar System , as as that will answer the known facts, and only to attribute to the proper motion o f each particular star the devia tions from the general law the stars seem to follow in ” those movements .

Herschel treated the problem in the simplest manner. Dealing with the proper motions Of seven bright stars

Sirius, Castor, Procyon , Pollux, Regulus , Arcturus, and — Altai r he separated their real from their apparent motions by simple geometrical methods, and reached the conclusion that the Solar System was moving towards a ” l o f point in the conste lation Hercules, the apex the solar motion being marked by the star Lambda Herculis . “ ” “ We may, he said , in a general way estimate that the solar motion can certainly not be less than that which 1 8 0 the Earth has in her annual orbit . I n 5 , Herschel ’ again attacked the problem , making use Of Maskelyne s he - ix table Of t proper motions Of thirty s stars . H is

’ result was in the main confirmatory Of hi s earlier con ” e “ lusions , the apex being again located in the con stellation Hercules. Herschel ’ s brilliant discovery was regarded with considerable incredulity by several o f his contem poraries e o n and successors . They s emed to feel that the data which he worked were too slender for a t rustworthy result n to be deduced. Bessel , the greatest practical astro omer o f n o the next generation, maintained that there was evidence in favour o f a motion towards a point in Hercules ; and even Sir John Herschel rejected his ’ 1 8 the father s conclusions . In 3 7 , Argelander attacked o f 0 question from a study Of the motion 3 9 stars. The result o f his investigation was to confirm abundantly ’ ’ Herschel s conclusions. Since Argelander s time, de termination after determination has been made, by of many illustrious mathematicians each generation . “ ” Every refinement has been exhausted , only, in the “ s of o the t triking words Ball , t confirm trut h of tha STELLAR R ESEARCHES 5 9 splendid t heory which seems to have been on e Of the ’ ” flashes Of Herschel s genius . o f The light the stars, no less than their motions, was a favourite su bject Of study with Herschel . H is first communication to the Royal Society dealt with the famous variable star Mira Ceti and several other papers o f O f dealt with the brilliancy the stars . The problem “ or stellar variation fascinated him . Dark spots, large portions Of the surface less luminous than the rest , turned o r alternately i n certain directions , either towards from ” “ 1 6 for us, he wrote in 79 , will account all the phe n o me na of periodical changes in the lustre of the stars so satisfactorily that we certainly need not look for any ” was other cause. But he aware of other variations the gradual increase or decrease o f the light o f certain e f o r s stars in th course o years centuries . He regarded a a pro blem Ofgreat practical interest the stability o r other wise O f the brilliance Of the Sun . His interest in the que stion Of stellar brightness and variation led to hi s determination Of the relative brightness Of the stars . Four catalogues o f comparative brightness o f stars were — communicated to the Royal Society the first on 2 5 th

u 1 6 o n 2 1 5 t 1 . Febr ary, 79 , the fourth February, 79 9 The observations on which these catalogues were based were 1 - made in the years 79 5 9 7, and Herschel seems to have attached S O much importance to the work that for three “ ” his years he discontinued sweeping Of the heavens . Two other catalogues were left unpublished at the his time Of death , and were first issued in the collected o f edition his works . The Observations he hi mself de “ f ” scribed as di ficult and laborious . He mentioned in the paper accompanyi ng his first catalogue the various o f causes error which had to be guarded against , such as ff moonlight , the di erent altitudes at which a star might be viewed , the uncertainty Of flying cloud , the scintil lation Of the stars , the zodiacal light , the aurora borealis, and dew or damp upon the glasses or specula when a 60 H ERSC H EL

telescope is used Nevertheless , H erschel completed his catalogues , and left behind him a work Of imperishable

Fo r - value. a hundred years the work was under estimated e by astronom rs , until , at the close Of the nineteenth century , the catalogues were reduced and discussed by the e . . a late Prof ssor E C Pickering, Of Harvard, who g ve ’ the following estimate o f the value of H erschel s work o f e 000 Herschel furnished Observations n arly 3 stars , from which their magnitudes a hundred years ago can now b e determined with an accuracy approaching that O f f e the best modern catalogues . The average dif erenc from the pho tometric catalogues is only i which includes the actual variations of the stars during a century, as well e o f as the errors o f both catalogu s . The error a Single comparison but little exceeds a tenth of a magnitude . ’ Herschel s Observations of starlight were not only 1 8 visual and telescopic . I n 79 he passed the light of a fe w stars Of the first magnitude through a prism appli ed

- to the eye glasses O f his reflectors . He found that the e light Of Sirius consisted of red , orange , yellow , gre n , : blue, purple , and violet that Betelgeux contained the same colours, but that the red was more intense than in

Sirius ; that Procyon contained more blue and purple , and Arcturus more red and orange than Sirius ; that Aldeba ran contained much orange and Vega much yellow , green , blue and purple. O f course, Herschel was unable to discern the dark lines in these spectra , but his observation deserves to be remembered as the

first application O f the prism to starlight . It is difli cul t to know whether to admire most the Observational skill o r the intellectual grasp displayed in we these subsidiary researches and cannot but feel , with a “ Ar go, a deep reverence for that powerful genius that has scarcely ever erred C HA PTER I V I I .

L S G S C O IN YEAR .

’ " O f B the beginning the nineteenth century, Herschel s t extraordinary activity began somewhat to abate. No his that his mind had become less acute , or interest in as t ronomy less marked . But it was physically i mpossi ble for any man to m aintain the standard of activity which H no e had been his for thirty years . e had w complet d his comprehensive surveys Of the heavens, and accord l d i ng y hi s studies became more and more specialise .

- The Sun and Saturn , the newly discovered asteroids , and n ot e several comets , and last but least , his exp ri ments o n o f light, occupied more and more his time . But he n ow allowed himself intervals o f rest between his investi ati o ns one O f g ; he found more time for music , always his chief delights , and in addition he gave himself 1 80 1 accom more opportunities for holidays . In July, , anied his son p by his wife and mJohn, then a lad Of nine , he visited Paris. Here he ade the acquaintance Of

Laplace, with whom he had many important conversa to tions , and was introduced Napoleon , then First Consul . ’ At 7 O clock on 8 th August the Minis ter Of the Interior conducted Herschel , along with Laplace and Count ’ to Rumford , N apoleon s palace at Malmaison . Herschel records in his journal that the First Consul , who met the on party i n the garden , politely put some questions ‘ t astronomical subjects . It was repor ed at the time that N apoleon ’ s astronomical k nowledge had astonished

. w s a e Herschel Such a app rently not the case. Twelv (6 1 ) 6 2 HERSCHEL

years later, i n conversation with the poet Campbell ,

Herschel contradicted this report. N he said, the First Consul did surprise me by his quickness and ver s a tili t on e y all subjects , but in science he se med to know

- e e o f little more than any well ducated g ntleman , and

e ou r o wn n . astronomy much l ss, for instance , than Ki g His general air was something like affecting to know i I more than he did know . I remarked his hypocr sy n concluding the conversation on astronomy by Observing how all these glorious views gave proofs Of an Almighty wisdom . With his keen , quick intuition , Herschel perceived the incongruity O f the man o f overweeni ng pride and vainglory taking t he Divine name u pon his o f lips and simulating a mock piety. The chief result ’ Herschel s visit to Paris was his el ection in 1 8 0 2 as o ne

Of the eight foreign associate s of the Fre nch Institute . e Summer holidays wer usually spent at Dawlish , with e his lifelong friend , Sir William Watson , and at Tunbridg e Wells, Brighton , and Ramsgate. Neverthel ss , his health began to fail by gradual stages . H is duties as ’ n so King s Astronomer, ominal far as scientific work was e concern d, were somewhat exacting , and as he grew Older he was less able to spend several hours in an even ing explaining the heavenly bodies to groups o f royal 1 806 and aristocratic visitors . In October, , the appear ance of a bright c o met attracted a large number of th e visitors to Slough . On the evening of the 4 , Carolin

Herschel narrates, two parties from the Castle came to see the e the comet , and during whole month my broth r had not an evening to himself. As he was then in the

f 0 - f e e a b midst o polishing the 4 oot mirror , r st b came so l utely necessary after a day spent in that most laborious work and it has ever been my Opinion that on the 1 4th Of October his nerves received a shock from which he never got the better afterwards ; for o n that day (in particular)he had hardly dismissed his troop of men , when visitors assembled , and from the ti me it was dark till CLO S I N G "EARS 63

o n - past midnight, he was the grass plot surrounded by between fifty and sixty persons without having time for putting on proper clothing o r for the least nourishment hi s passing lips . Among the company, I remember , were

‘ o f Gal it zi n the Duke Sussex , Prince , Lord Darnley, a ”

o f f . number O ficers, Admiral Boston , and some ladies

This tremendous strain told on Herschel , and the result was that in the spring he became dangerously ill. Caro u s on 2 6 th 1 80 S O line tells that February, 7 , he was ill she was see 8 th that even not allowed to him , and u ntil

March his recovery was despaired Of. However , he wa s rallied and recovered , but his health permanently n e e e impaired . But his mi d was as cl ar as ev r , and som of his most remarkable papers were written after his ill — O f 1 8 1 1 h e ness that , in which developed the nebular o f 1 8 1 1 8 1 1 8 1 8 o n the hypothesis, and those 4 , 7 , and , o f construction the heavens . Physically, however, he was unequal t o the task Of attending to his great tele oth 1 8 1 scopes . On 3 September , 5 , his sister recorded “ i for o r that his strength s now, and has the last two to three years , not been equal the labour required for

- polishing 40 foot mirrors . And it was only by little ex cu rsio ns and absences from hi s workro o ms t he for some time recovered from the eff ects Of over - exertion Dur ’ sad ing these last years, Caroline s diaries make reading, for they record little more than the gradual decay o f ” health and vigour in the best and dearest of brothers . His inability to repolish his great m irror was a bitter disappointment to him , and he became depressed and sorrowful . She afterwards recorded that when all hopes for the return O f vigour and strength n ecessary fo r re a e s ming the unfinished task was gone, all ch erfulness and spirits had also forsaken him . Every nerve Of ” the c - so lear man had been unstrung by over exertion, “ that a further attempt at leaving the work complete ” 1 8 1 his . fo became impossible In 9 , before departure r “ a holiday at Bath, the last moments before he stepped 64 HER SCH E L into the carriage were spent in walking through his to library and workrooms, pointing with anxious looks every shelf and drawer, desiring me to examine all and of to make memorandums them as well as I could . H e to was hardly able support himself, and his spirits were so l o w that I found difficulty in commanding my voice so far as to give him the assurance he should find on his no t return that my time had been misspent . O ld But H erschel was not always , even in extreme age, depressed and gloomy . A German visitor to Slough , in “ 1 8 1 : 9 , thus described the great astronomer While we e were standing by the gr at telescope, which we more e admired than compr hended , its master appeared , a cheer

O ld - H ow ful man aged eighty one . unassumingly did he make his communications I H ow lightly did he ascend the steps to the gallery " With what cal m pleasure did he seem to enjoy the success o f his efforts e e in life . All accounts from his native country s em d to me please him , although the German language had beco e o m somewhat less familiar to his ear. Aft r a short c o u r e e versation , we took leave, charged with friendly gr t i n gs to all beyond the sea who might still remembe r him . 1 8 1 6 he re On 5 th April , , received the first mark of cognition from the British Government— the third class

Of the Hanoverian Guelphic Order. In the following e month he was created a Knight of the same Ord r . In 1 8 20 o f — n ow , when the Astronomical Society London — e the Royal Astronomical Society was fou nded , Hersch l e was elected as the first Pr sident . H is health did not he n e permit him to attend the meetings, but commu icat d — — “ ” his last paper ou double stars to its Memoirs in

1 8 2 1 . ’ Caro line Herschel s Memoirs record the agony o f soul through which she passe d as her brother became weaker 1 8 1 l od and weaker . In 9 he sent a note across to her g O f ings , notifying her Of the appearance a great comet

66 HERSCH EL

she i 1 8 2 2 had arr ved in Hanover, in October , , than she realised her great mistake . She found herself among

‘ uncongenial company . I n the last hope Of finding in Dieterich a brother to whom I might communicate all ” O f she my thoughts past , present and future , wrote 1 8 2 s aw to her nephew in 7 , I myself disappointed the very first day o f ou r travelling o n land . For let me o n e r touch what topic I would , he maintain d the cont ary , which I soon sa w w as done merely because he would ” n allow no o e else to know anything but himself. The Old lady could find no congeniality in the company o f old a soured, fractious man , and among people who could n o e t enter in the slightest into her scientific inter sts . “ ” s et she From the moment I foot on German ground , “ ”

w as e . e said , I found I alon She d scribed herself as leading a “ solitary and useless ” life— “ not finding Hanover or anyone in it like what I left when the best me him Of brothers took with to England in August,

S O Solitary her life was, far as congeniality went, but e n by no means useless . Soon after her settl me t in ’ she o f e Hanover , formed a catalogue all her broth r s a I n 1 8 2 nebul and clusters , arranged in zones . April , 5 , S he n e e forwarded this to her ephew , John H rschel , th n e e o f e e ngaged in his r view th se Obj cts . This catalogue “ was described by Sir David Brewster , as an extra ordinary monument Of the un extinguished ardour o f ” - a lady of seventy five in the cause of abstract science . It was rewarded by the presentation to her of the Gold o f o 1 8 2 8— a n Medal the Royal Astronomical S ciety, in o e S he honour by which , with characteristic m d sty, said ” “ 1 8 she was more shocked than gratified . In 3 5 she was elected an honorary member of the Royal A stron o o f e e mical Society, membership which was not th n op n to women ; a n d in 1 8 3 8 the Royal Irish Acad emy e n e rolled her name among its members . Th se honours sat very lightly on her. Saying too much of what I CLOS IN G YEARS 67

“ 1 8 26 too have done , she said in , is saying l ittle Of

fo r . hi m , he did all I was a mere tool which he had the trouble of sharpe ning and adapting for the purpo se he ”

o f . wanted it , for lack a better

As the years passed , and her vitality ebbed , all her affection became concentrated in the one bein g whom She felt und erstood her and with whom she had co m — he munity Of interests her nephew John . S followed t o O f his his career with pride, as a worthy sequel that father ; his visits to H anover were t o her oases in the desert of her e xperience he and his wife were her prin e e her cipal correspond nts . She wrot last letter to her e e rd 1 8 6 : she - si x n ph w , December 3 , 4 was then ninety ,

e fo r - an d had surviv d her brother twenty four years .

1 8 . During 47 , tenderly nursed by her niece, Mrs Knip ’ n pi g, the only one O f Dieterich s family who really fo r she on th sought to care her , slowly sank , and 9 1 8 8 S he e — January, 4 , pass d away within two months Of

- completing her ninety eighth ye ar . She was buried besid e her parents i n the churchyard of the Ga rten ge de o mei n . at Hanover Her epitaph , c mposed by hersel f, “ records that the eyes o f her who is glorified were here own below turned to the starry heavens . Her discoveries O f comets and her participati o n in the immortal labours of e her brother, William Herschel , bear witn ss of this ” e to futur ages . e e t o o n Future ag s are not lik ly f rget Caroli e Herschel .

Her own original work was , it is true, comparatively - sacrifi ci n o small ; but her self g dev tion to her brother , her performance Of the countless small petty drudgeries o f e her e for his scientific lif , t nder care his welfare and o comf rt, give her an honourable place among women Of n lasti g fam e . As long as William Herschel i s re e e memb red , his sist r Caroline will not be forgotten . A s “ e e has be n truly said , she shin s and will continue to ” the e she shine by reflect d light that loved . of was n The career the younger Herschel , in ma y 68 HERSCHEL

O f respects , the sequel to , and completion , that Of his father . John Frederick William Herschel , born within of e o n th 1 2 the shadow the great t lescope, 7 March , 79 , e was educated at H itcham , Eton and Cambridg . At the University he was a distinguished student . particularly in mathematics , and graduated as Senior Wrangler in 1 8 1 hi s - 3 . He was in no hurry to choose life work , nor ’ d e the was there any nee . Since his father s marriag , e family had b en in easy, i f not affluent circumstances . re His father had destined him for the Church , but he p e the ferred the study of law . He nev r practised at Bar, e e howev r, and at last decided for a sci ntific career . In “ 1 8 1 6 he j n formed a correspondent that he was going ’ - under his father s directions to take up star gazing ”.

H e had at first no definite inclination in that direction , ’ but he decided to complete his father s work . During ’ re- his father s lifeti me, he examined many binary stars , e in conjunction with Sir James South, and for th se Observations he receiv ed the Lalande Prize O f the French Academy and the Gold Medal o f the Astronomical

Society. In 1 8 2 8 he succeeded in rediscovering the genuine o f satellites Uranus , and in the same year commenced ’ - e hi s review o f his father s nebul a and star clust rs . The n oo completion Of this work was sig alised by knighth d . ’ 1 8 he deci ded Then , in 3 3 , after his mother s death , to ’ extend his father s surveys to the southern hemisphere . e o n H e transport d his great telescope to Cape C lo y . and e e o 1 8 to 1 8 8 at Feldhausen , n ar Cap Town , fr m 3 4 3 , he s o e o e wept the s uthern ski s , catal guing doubl stars , cluste rs and nebul a ; and after nin e years o f ardu o us “ the n n o e O f labour, mo umental volume k wn as R sults ” Astronomical Observations at the Cape o f Good H o pe ow e e was published . Meanwhile, honours were sh r d thick and fast upon the astronomer ; he was create d e his n n a baronet aft r retur from South Africa , ma y " degrees were conferred pon him , and learned societies CLO S IN G YEARS 69 vied with each other in enrolling his name among their not re- members . On his return to England , he did erect his telescopes and his career as an Observer was Closed . During the latter part o f his life he was regarded as the Of greatest English astronomer his day, and on his death o n 1 8 1 5 th May, 7 , at his home at Collingwood in Kent, he was interred in Westminister Abbey, close to the of grave Newton . o f Sir John Herschel was survived by three sons , e 1 8 2 whom only the eld st, Sir William James Herschel ( 3

did not inherit the family taste for astronomy . e son 1 8 6 The s cond , Alexander Stewart Herschel ( 3 e Professor at Durham Colleg , devoted consider a able attention to meteoric stronomy, while the younger son e , Colonel John Hersch l , in his earlier days undertook s ect rO S CO ic O f a a p p examination Southern nebul . The names Of a grand- daughter and of a great grandson o f — Sir William Herschel Miss Francesca Herschel and Rev . — . . on o f J C W . Herschel appear the roll of Fellows the to Royal Astronomical Society, testify that the family i s o f of the still distinguished by love the Oldest sciences . I I I C HAPTER V .

P S T D F ER ONALI Y A N IN L" ENCE .

SCIEN TI FIC biographies are sometimes painful reading painful because in them we are occasionally brought e face to face with the flaws in gr at characters, the petti T e nesses Of great minds . h biography Of Herschel does Th e not belong to that class . e charact r which shines ’ e through his writings , through his sist r s memoirs , and through the correspondence and comments Of contem orari es of e p is that a genial , kindly, arnest m an . In private life he was a good husband and father , a loving son brother and a devoted . H is less fortunate relatives found in hi m a ready and willing helper : he maintained his brother Alexander aft er his retirement until his death 1 8 2 1 e the in . Even to Dieterich , the shiftless memb r of be family, he was unfailingly kind and sympathetic, i n O f 2000 e q u eath g to him a sum £ . From earli st years “ ” he was to Caroline the best and dearest Of brothers , and that his care for her did not close with his death is to o f evident from his bequest her an annuity. Alike in a times of dversity and prosperity , he was ever helpful and lri ri ci . He had none of that aloofness which has Often char acterised men O f science. He was at all times ready to reply to correspondents and to answe r inquiries . H e was always accessible and never pedantic . The poet Campbell has given us a charming word - picture Of the 1 astronomer in private life. Writing to a friend on 5 th “ 1 8 1 : September, 3 , Campbell said I wish you had been e with me the day b fore yesterday, when you would have (70) PERSO N ALITY A ND I NFLUENCE 7 1

joined me , I am sure , deeply in admiring a great, simple , — o O ld . g od man Dr Herschel . His simplicity, his — ki ndness , his anecdotes, his readiness to explain and — make perfectly conspicuous too his own sublime con ce ti on s o f p the Universe , are indescribably charming . - sat H e is seventy six , but fresh and stout , and there he ’ nearest the door at his friend s house , alternately smiling o r o r at a joke, contentedly sitting without share notice n O f in the conversation . Any trai conversation he follows implicitly ; anything you ask he labours with a sort of o f boyish earnestness to explain . Speaking himself he said , with a modesty of manner which quite overcame O f me, when taken together with the greatness 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 ’ o f years to reach this earth ’ Herschel s close friendships were few but enduring.

Sir William Watson , Sir Joseph Banks , Dr. Maskelyne, f and Mr. Aubert, were intimate riends and correspondents ’

O f . e astro no many y ars standing. Among continental S chrOter mers , Lalande, Bode, and , were the most frequent correspondents . With men of science his relations were as harmonious as with humble amateurs NO or anxious inquirers . acrimonious controversies O f disturbed the even tenor his scientific career. The e o f 1 nearest approach to h at was in his paper 79 3 , when ’ he made his spirited refutation of S chrOte r s alleged di s covery of high mountains in Venus and on that occasion his words were probably written more in the spirit of S chrOter banter than controversy. At least, seems to so con have regarded them , for the two astronomers d ti nu e to be friendly correspondents .

- H is mind was many sided , and to the end his interests

v aried. for were His love music never left him , nor did that early interest in metaphysical and logical reasoning which prompted the seventeen - year- Old musician to spend all 7 2 HERSC HE L

’ “ his earnings on a copy of Locke s Essay on the Human ” Understanding . His early contri butions to the Bath Literary Society included a number O f philosophical “ ne o f hese e f s cu papers . O ,t d alt with the utility o pe lative inquiries In this there occurs the following e O f passag , which gives us some idea the catholicity of his mind and also an insight into the secret of hi s success “ as a man of science : It was said that speculation and metaphysics were of little use to mankind . This I deny. The perfection O f o u r nature is evidently to be looked O f n for in the superior powers reason and speculatio . What would all experiments avail if we should stop there and not argue upon them so as to draw general con cl u si on s ? And how can we argue and draw conclusions if the superi o r intellectual powers are not improve d by frequ e nt exercise in speculative researches ? Half a dozen experiments made with judgment by a person who reasons well are wo rth a thousand random Observa O f e tions of insignificant matters fact . But s tting aside O f the very Obvious consequences improved faculties , the subjects o f mere speculative knowledge are o f the highest concern to those who love wisdom . By metaphysics we the are enabled to prove the existence Of a First Cause, o f I nfinite Author all dependent beings . By mathematics we come to have a just id e a of the superlative perfectio n

we . Of H is works . By logic can prove them to others By ethics we are made sensible Of our duty towards the ” f o r - Author O our existence and to u fellow creatures . This full - orbed conception of the world seems to have saved Herschel from falli ng under the influence of the o f spirit O f scepticism then prevalent among men science . — — I n his mind keen and logical as it was there seems to have been no conflict between the scientific and re l i o s i u . g instincts I n a letter to a correspondent, dated I st 1 January, 794 , he said, quite simply and without “ aff ectation : It i s certainly a very laudable thing to re eive a of c instruction from the gre t Workmaster Nature,

74 H ERSCH EL

e telescop , Herschel was enabled to take the whole field ’ O f o o o b en Observati nal astron my f r is province . He or mously extend ed knowledge o f the Sun ; and his solar e e theory , untenable though it prov d , was the first att mpt to system atise and co- ordinate the k nown facts c o ncerning the Sun . His work on the various worlds o f the Solar System marked the foundation Of modern planetary o o n 1 top graphy . H is paper Mars in 784 constituted n O f The Martian astronomy a disti ct branch the science . scientific study of the Saturnian system may be said to have begun with hi m ; he was the author of the first s erious attempt to e xplain the atmospheric phenomena o n e o e e — Jupit r. He not only disc v r d Uranus and thus — prepared the way for the discovery o f N eptu ne but he persistently scrutinised its disc until he ascertained its e e Siz and mass . H is discov ries of satellites did not o the e re exhaust his w rk on s condary systems . His markable intuition that the rotation periods o f satellites are equal to their times of revolution was one O f the f flashes o his genius . e e In st llar astronomy he discover d binary stars, and — thus prov e d what others had suspected that the l a w o f co n gravitation was of universal application . With summate skill and audacity he attacked the highly ff i o o di cult and elusive pr blem of the solar m tion, and e a nd successfully measuring its rat direction, he demon o f st ra ted further the ess ential kinship Sun and stars . H is eff orts to know the construction o f the heavens he the were unsuccessful , but laid foundation of a new — branch o f astronomy that dealing with the di st ribu tion and motions o f the stars ; and in addition dis covered suns and worlds in process of formation . Her schel was the first student o f nature to point to evolution in progress and to Classi fy natural objects i n evolutionary

array .

Above all , Herschel enormously widened the mental O f horizon man . H is researches extended the universe P ERSONALITY A ND I N FLUENC E 7 5

“ — i n o both in space and time very truth , he br ke through the barriers o f the Skies H e revealed to the wondering gaze of his contemporaries star upon star, O f system upon system , cluster upon cluster. Speaking “ these revelations Horace Walpole said : I f there are twenty millions Of worlds , why not as many and as ? ’ many and as many more Oh , one s imagination cracks H i s researches revealed the Earth in its true — light o ne revolving globule chained to a tiny star ;

- a dust grain in the infinite. Every branch o f Observational astronomy bears to ’ O f this day the i mpress H erschel s powerful personality.

Since his death , the science has greatly advanced ; o its h rizons have widened , and innumerable new facts d have been brought to light . Yet, even to ay, we can not but agree with the verdict Of a prominent American 1 astronomer that Herschel was so far in advance of his age that we are just now beginning to appreciate his ” sa o f genius , and we may safely y that in the annals a o f e stronomical science the name William Hersch l , n pioneer Of moder astronomy , will shine with increasing

o n . To lustre as the years roll him , indeed, we may f o f o apply , with peculiar fitness , the beauti ul words L ng fellow

W e e a sta en e O n r r qu ch d high , For a es wo i ts t g uld ligh , S t t a e n ow nw a s o the sk ill r v lli g d rd fr m y, n r t Shi e on ou mor al s ight .

S O wh en a great man di es ; For years beyond our k en The light he l eaves b ehi nd him lies " on the at s o f men p p h .

1 P o T . S ee r f. . J . J .

D " APPEN I .

F D T S IN S L’ S L F I . CHIE A E HER CHE I E .

n 1 th m 1 8 B o n e No e . r at Ha ov r, s ve b r, 73

Se ed i n E n an 1 . ttl gl d, 75 7 A o n d o n O a on Cha e i n B a 1 66 pp i te rga ist Of ct g p l th, 7 . F o ed astron omi cal observati on 1 th 1 Fe ar 66 . irst rec rd , 9 bru y, 7

B an on e e 1 . eg to c struct t lescop s, 7 73 F e d d tel eSCO ic e v t on I st I irst r cor e p Obs r a i , March, 774.

s o e Of " n I th 1 8 1 . Di c v ry ra us, 3 March , 7 E e t ed Fe w O f the R o So e m e 1 8 1 l c llo yal ci ty, Dece b r, 7 . ’ m 1 8 2 A n ted K n As on e . ppoi as i g s tr o r, 7 f f m 1 s o o P o e ot on O S o S e 8 . Di c very r p r M i lar yst , 7 3

F s a e on Con str t on e en 1 8 . ir t p p r the uc i of the H av s, 7 4

- s eo of the " n e s n d d 1 8 . Di c th ry iv r e propou e , 7 5

a e 8th 1 8 8 . M rriag , May, 7

n est at n n o t 1 1 . I v ig io Of ebul us s ars, 79

e Of e n s r 1 8 0 2 . Discov ry r volvi g double ta s, Abandon men t o f disc-theory and en unciation o f nebular o 1 8 1 1 hyp thesis, .

La e s ed 1 8 2 1 . st pap r publi h ,

d S o 2 th A s 1 8 2 2 . Die at l ugh, s ugu t

B B G P II . I LIO RA HY.

The following works may be reco mmended for those who ’ desire a closer acquai ntance with H erschel s life and work

r r s o n r a n (i) S ta nda d sou ce f i f o m ti o .

The Co e ed S en fi Pa e s Of S m e ll ct ci ti c p r ir ~ Willia Hersch l

a n d t on . L . E . e wi th B i o raphic l i tro uc i by Dr J . Dre r — g y i n two volumes (publi shed by the R oyal Soci ety

a nd the R oyal Astronomical Society). (77) O ne e s he M rs. li H r c l, by J oh n H ersehe

11 P o u l a r i o r a /z es ( ) p B g p i .

The e s e an d ode n A t on om b A nes . H r ch ls M r s r y, y g M Cl erk e (Cassell

m e he and H is o b a mes S me T . T . Willia H rsc l W rk, y J i (

Clark).

S am e e H i s L fe an d or s b E . S . ir Willi H rsch l : i W k , y n H olde . B o a h e of s n s ed S en t fi M en b Fran ois i gr p i s Di ti gui h ci i c , y e

Arago .

' ’ l fi stor it a l Works dea l i n wi t/z H erselzel s l a t e i n M oder n (iii) , g p A str on om y .

sto o f P s A on om R o er Gr n t B a dw n . Hi ry hy ical str y, by b t a ( l i ) s o A t on om d n the N n e een Cent Hi t ry of s r y uri g i t th ury, by

n M e e . 81 . . Ag es . Cl rk (A C Black)

A sto Of As on om b A t B e o n . Hi ry tr y, y r hur rry (J h Murray) ’ A Cen r P o ess i n A t no m e to e son tu y s r gr s ro y, by H c r Macph r

(Blackwood).

n m e en . A o Of A t o o . . B an Hist ry s r y, by W W ry t (M thu )

AB ERDEEN : TH E " NIVER S IT" PRES S P I O N EE R S O F P R O G R ES S

M EN O F SC I EN C E

W ith P ort rai t . H MA M A B . s e. F. R . S . Edited by S . C AP N, . ,

r l th 28 . net . P ape , l s . ; C o ,

H ER S C H EL .

EC O R AC P H E R S O N By H T M ,

J R I T " OS EP H P ES LE .

D EA K H . P COC . By .

R J O S E PH D ALTON H O OK E .

F . O . OW ER S C . D F . R . S . By B , . ,

GALI LE O .

W . W . B R"AN Ro a O se a t o G e enw . By T , y l b rv ry , r ich

R D " M I C HAEL FA A A .

A R W H E R D S c J O . By . . C T , .

A ALFR ED R " S S ELL WALL C E .

he S t o of a e a t D s o e e LANC ELO T HOGB EN T ry gr i c v r r . By T . , B c B . A . , . S . O thers i n re a ra ti on ( p p . )

I N A V O" AG E S PAC E .

“ A o rs e of S i x Le t e s a a te t o a J en e A t o C u c ur d p d uv il udi ry , H H T " R N E R D S c F R S S a vi l i a n P o e s so by . . , . . , . . r f r f Ast on o i n t he " n e s t O f Ox o W t o e 13 0 O r my iv r i y f rd . i h v r st at on s ot oa s Gs n e t Illu r i . Cl h b rd , . .

E ON D R S O F WIR S T TH W E ELE S ELE GR APH" .

Ex a n e i n s e t e s fo r t he n on - t e n a ea e r pl i d impl rm ch ic l r d . By

A LE M G M . A B s e n e s t J F I N . . " P o e s sor Of . . , , iv r i y r f E e t a E n n ee n I n t he " n e s t of Lon on e t c W t l c ric l gi ri g iv r i y d , . i h

n e s D a a s . ot oa s um ro u i gr m Cl h b rd .

O A N D W T WE G ET FR OM C AL HA IT .

A a n e Of A e S n EL EL L R o e e . RA P H A D O A m c ppli d ci c By M , s ome t ime P rofe s so r O f Ch e mi st ry i n Fi n s bury Te ch n ic a l

o e e . st a t e . ot "S . 6d n et C ll g Illu r d Cl h , . .

‘

. P . 8 . K O DO c . . , L N N

THI S B O OK I S D" E ON TH E LA S T DA TE S TAM P ED B EL OW

A N I NI TI A L FI N E OF 25 CEN TS

W I LL B E A S S ES S ED FO R FA I L " R E TO R ET" R N

TH IS B O O K O N T H E D A TE D " E. T H E P EN A L T" W I L L I N C R EA S E TO 5 0 C EN TS O N T H E FO " R TH D A " A N D TO O N TH E S EV EN TH D A "

O V ER D " E.