THE CENTURY SCIENCE SERIES.
EDITED BY SIR HENRY E. ROSCOE, D.C.L., LL.D., F.R.S.
THE HERSCHELS
AND
_MODERN ASTRONOMY_
The Century Science Series.
EDITED BY
SIR HENRY E. ROSCOE, D.C.L., F.R.S., M.P.
=John Dalton and the Rise of Modern Chemistry.=
By Sir HENRY E. ROSCOE, F.R.S.
=Major Rennell, F.R.S., and the Rise of English Geography.=
By CLEMENTS R. MARKHAM, C.B., F.R.S., President of the Royal
Geographical Society.
=The Herschels and Modern Astronomy.=
By Miss AGNES M. CLERKE, Author of “A Popular History of
Astronomy during the 19th Century,” &c.
_In Preparation._
=Justus von Liebig: his Life and Work.=
By W. A. SHENSTONE, Science Master in Clifton College.
=Michael Faraday: his Life and Work.=
By Professor SILVANUS P. THOMPSON, F.R.S.
=Clerk Maxwell and Modern Physics.=
By R. T. GLAZEBROOK, F.R.S., Fellow of Trinity College,
Cambridge.
=Charles Lyell: his Life and Work.=
By Rev. Professor T. G. BONNEY, F.R.S.
=Humphry Davy.=
By T. E. THORPE, F.R.S., Principal Chemist of the Government
Laboratories.
=Pasteur: his Life and Work.=
By ARMAND RUFFER, Director of the British Institute of
Preventive Medicine.
=Charles Darwin and the Origin of Species.=
By EDWARD B. POULTON, M.A., F.R.S., Hope Professor of Zoology
in the University of Oxford.
=Hermann von Helmholtz.=
By A. W. RÜCKER, F.R.S., Professor of Physics in the Royal
College of Science, London.
CASSELL & COMPANY, LIMITED, _London; Paris & Melbourne_.
[Illustration: SIR WILLIAM HERSCHEL.
_Ætat. 50._
(_From Abbott’s painting in the National Portrait Gallery._)]
_THE CENTURY SCIENCE SERIES._
THE HERSCHELS
AND
_MODERN ASTRONOMY_
BY
AGNES M. CLERKE
AUTHOR OF
“A POPULAR HISTORY OF ASTRONOMY DURING THE 19TH CENTURY,”
“THE SYSTEM OF THE STARS,” ETC.
CASSELL AND COMPANY, LIMITED
_LONDON, PARIS & MELBOURNE_
1895
ALL RIGHTS RESERVED
[Illustration]
PREFACE.
The chief authority for the Life of Sir William Herschel is Mrs. John
Herschel’s “Memoir of Caroline Herschel” (London, 1876). It embodies
Caroline’s Journals and Recollections, the accuracy of which is
above suspicion. William himself, indeed, referred to her for dates
connected with his early life. The collateral sources of information
are few and meagre; they yield mere gleanings, yet gleanings worth
collecting. Professor E. S. Holden has had recourse to many of them
for his excellent little monograph entitled “Herschel, his Life and
Works” (London, 1881), which is usefully supplemented by “A Synopsis
of the Scientific Writings of Sir William Herschel,” prepared by the
same author with the aid of Professor Hastings. It made part of the
Smithsonian Report for 1880, and was printed separately at Washington
in 1881. But the wonderful series of papers it summarises have still
to be sought, one by one, by those desiring to study them effectually,
in the various volumes of the _Philosophical Transactions_ in which
they originally appeared. Their collection and republication is,
nevertheless, a recognised desideratum, and would fill a conspicuous
gap in scientific literature.
Sir John Herschel’s life has yet to be written. The published materials
for it are scanty, although they have been reinforced by the inclusion
in the late Mr. Graves’s “Life of Sir William Rowan Hamilton” (Dublin,
1882–9) of his correspondence with that remarkable man. The present
writer has, however, been favoured by the late Miss Herschel, and by
Sir William J. Herschel, with the perusal of a considerable number of
Sir John Herschel’s, as well as of Sir William’s, manuscript letters.
She also gratefully acknowledges the kind help afforded to her by Lady
Gordon and Miss Herschel in connection with the portraits reproduced
in this volume. For detailed bibliographical references, the articles
on Sir John, Sir William, and Caroline Herschel, in the “Dictionary of
National Biography,” may be consulted.
CONTENTS.
PAGE
CHAPTER
I.--EARLY LIFE OF WILLIAM HERSCHEL 9
II.--THE KING’S ASTRONOMER 32
III.--THE EXPLORER OF THE HEAVENS 53
IV.--HERSCHEL’S SPECIAL INVESTIGATIONS 75
V.--THE INFLUENCE OF HERSCHEL’S CAREER ON MODERN ASTRONOMY 98
VI.--CAROLINE HERSCHEL 115
VII.--SIR JOHN HERSCHEL AT CAMBRIDGE AND SLOUGH 142
VIII.--EXPEDITION TO THE CAPE 162
IX.--LIFE AT COLLINGWOOD 183
X.--WRITINGS AND EXPERIMENTAL INVESTIGATIONS 203
ILLUSTRATIONS.
PAGE
PORTRAIT OF SIR WILLIAM HERSCHEL _Frontispiece_
PORTRAIT OF CAROLINE HERSCHEL 115
PORTRAIT OF SIR JOHN HERSCHEL 142
THE HERSCHELS
AND
MODERN ASTRONOMY.
CHAPTER I.
EARLY LIFE OF WILLIAM HERSCHEL.
William Herschel was descended from one of three brothers, whose
Lutheran opinions made it expedient for them to quit Moravia early
in the seventeenth century. Hans Herschel thereupon settled as a
brewer at Pirna, in Saxony; his son Abraham rose to some repute as
a landscape-gardener in the royal service at Dresden; and Abraham’s
youngest son, Isaac, brought into the world with him, in 1707, an
irresistible instinct and aptitude for music. Having studied at Berlin,
he made his way in 1731 to Hanover, where he was immediately appointed
oboist in the band of the Hanoverian Guard. A year later he married
Anna Ilse Moritzen, by whom he had ten children. The fourth of these,
Frederick William, known to fame as _William_ Herschel, was born
November 15th, 1738.
His brilliant faculties quickly displayed themselves. At the
garrison-school he easily distanced his brother Jacob, his senior
by four years, and learned besides, privately, whatever French and
mathematics the master could teach him. He showed also a pronounced
talent for music, and was already, at fourteen, a proficient on the
hautboy and violin. In this direction lay his manifest destiny. His
father was now bandmaster of the Guard; he was poor, and had no other
provision to give his sons than to train them in his own art; and
thus William, driven by necessity to become self-supporting while
still a boy, entered the band as oboist in 1753. They were a family
of musicians. Of the six who reached maturity, only Mrs. Griesbach,
the elder daughter, gave no sign of personally owning a share in the
common gift, which descended, nevertheless, to her five sons, all noted
performers on sundry instruments.
William Herschel accompanied his regiment to England in 1755, with his
father and elder brother. He returned a year later, bringing with him
a copy of Locke “On the Human Understanding,” upon which he had spent
the whole of his small savings. Two of the three volumes thus acquired
were recovered by his sister after seventy years, and transmitted to
his son. The breaking-out of the Seven Years’ War proved decisive as to
his future life. Campaigning hardships visibly told upon his health;
his parents resolved, at all hazards, to rescue him from them; and
accordingly, after the disaster at Hastenbeck, July 26th, 1757, they
surreptitiously shipped him off to England. By this adventure, since he
was in the military service of the Elector of Hanover, George III. of
England, he incurred the penalties of desertion; but they were never
exacted, and were remitted by the King himself in 1782.
William Herschel was in his nineteenth year when he landed at Dover
with a French crown-piece in his pocket. Necessity or prudence kept
him for some time obscure; and we next hear of him as having played a
solo on the violin at one of Barbandt’s concerts in London, February
15th, 1760. In the same year he was engaged by the Earl of Darlington
to train the band of the Durham Militia, when his shining qualities
brought him to the front. The officers of the regiment looked with
astonishment on the phenomenal young German who had dropped among them
from some cloudy region; who spoke English perfectly, played like a
virtuoso, and possessed a curious stock of varied knowledge. Their
account of him at a mess-dinner excited the curiosity of Dr. Miller,
organist and historian of Doncaster, who, having heard him perform a
violin solo by Giardini, fell into a rapture, and invited him on the
spot to live with him.
He left nothing undone for the advancement of his _protégé_; procured
for him tuitions and leading concert engagements; and encouraged him,
in 1765, to compete for the post of organist at Halifax. Herschel’s
special qualifications were small; his chief rival, Dr. Wainwright, was
a skilled player, and at the trial performance evoked much applause
by his brilliant execution. Only the builder of the organ, an odd
old German named Schnetzler, showed dissatisfaction, exclaiming:
“He run about the keys like one cat; he gif my pipes no time for to
shpeak.” Then Herschel mounted the loft, and the church was filled
with a majestic volume of sound, under cover of which a stately melody
made itself heard. The “Old Hundredth” followed, with equal effect.
Schnetzler was beside himself with delight. “I vil luf dis man,” he
cried, “because he git my pipes time for to shpeak.” Herschel had
virtually provided himself with four hands. A pair of leaden weights
brought in his pocket served to keep down two keys an octave apart,
while he improvised a slow air to suit the continuous bass thus
mechanically supplied. The artifice secured him the victory.
This anecdote is certainly authentic. It is related by Dr. Miller from
personal knowledge. Nor is it inconsistent with a story told by Joah
Bates, of King’s College, Cambridge, a passionate lover of music.
Repairing to Halifax, his native place, to conduct the “Messiah” at
the opening of a new organ, he was accosted in the church by a young
man, who asked for an opportunity of practising on it. Although as yet,
he said, unacquainted with the instrument, he aspired to the place of
organist; and the absolute certitude of his manner so impressed Bates
that he not only granted his request, but became his warm patron.
The young man’s name was William Herschel. We hear, further, on Dr.
Burney’s authority, that he played first violin in Bates’s orchestra.
But the tide of his fortunes was flowing, and he knew how to “take it
at the flood.” Early in 1766 he removed to Bath as oboist in Linley’s
celebrated orchestra, which played daily in the Pump Room to enliven
the parade of blushing damsels and ruffling gallants pictured to our
fancy in Miss Austen’s novels. Bath was then what Beau Nash had made
it--the very focus of polite society. Turbans nodded over cards; gigs
threaded their way along Union Passage; Cheap Street was blocked with
vehicles; the Lower Rooms witnessed the nightly evolutions of the
country-dance; the Grove, as Doran reminds us, was brilliant with
beauty, coquelicot ribbons, smart pelisses, laced coats, and ninepins.
The feat of “tipping all nine for a guinea” was frequently performed;
and further excitement might be had by merely plucking some lampoons
from the trees, which seemed to bear them as their natural fruit.
Music, too, was in high vogue. The theatres were thronged; and Miss
Linley’s exquisite voice was still heard in the concert-halls.
On the 4th of October, 1767, the new Octagon Chapel was opened for
service, with Herschel as organist. How it was that he obtained this
“agreeable and lucrative situation” we are ignorant; but he had that
singular capacity for distinction which explains everything. The
Octagon Chapel became a centre of fashionable attraction, and he soon
found himself lifted on the wave of public favour. Pupils of high
rank thronged to him, and his lessons often mounted to thirty-five a
week. He composed anthems, psalm-tunes, even full services for his
assiduously-trained choir. His family were made sharers in his success.
He secured a post in Linley’s orchestra for his younger brother
Alexander, in 1771; and he himself fetched his sister Caroline to Bath
in 1772. Both were of very considerable help to him in his musical and
other enterprises, the latter of which gradually gained ground over the
former.
Music was never everything to William Herschel. He cultivated it with
ardour; composed with facility in the prevalent graceful Italian style;
possessed a keen appreciation and perfect taste. But a musical career,
however brilliant, did not satisfy him. The inner promptings of genius
told him to look beyond. The first thirty-five years of his life
were thus spent in diligently preparing to respond to an undeclared
vocation. Nothing diverted him from his purpose of self-improvement.
At first, he aimed chiefly at mastering the knowledge connected
with his profession. With a view to the theory of music, “I applied
myself early,” he said, in a slight autobiographical sketch sent to
Lichtenberg at Göttingen, “to all the branches of the mathematics,
algebra, conic sections, fluxions, etc. Contracting thereby an
insatiable desire for knowledge in general, I extended my application
to languages--French, Italian, Latin, English--and determined to devote
myself entirely to the pursuit of knowledge, in which I resolved to
place all my future enjoyment and felicity. This resolution I have
never had occasion to change.” At Bath, in the midst of engrossing
musical occupations, his zeal for study grew only the more intense.
After fourteen or sixteen hours of teaching, he would “unbend his mind”
by plunging into Maclaurin’s “Fluxions,” or retire to rest with a basin
of milk, Smith’s “Opticks,” and Ferguson’s “Astronomy.” He had no
sooner fallen under the spell of this last science than he “resolved to
take nothing upon trust, but to see with my own eyes all that other men
had seen before.”
He hired, to begin with, a small reflector; but what it showed him
merely whetted his curiosity. And the price of a considerably larger
instrument proved to be more than he could afford to pay. Whereupon
he took the momentous resolution of being, for the future, his own
optician. This was in 1772. He at first tried fitting lenses into
pasteboard tubes, with the poor results that can be imagined. Then he
bought from a Quaker, who had dabbled in that line, the discarded
rubbish of his tools, patterns, polishers, and abortive mirrors; and in
June, 1773, when fine folk had mostly deserted Bath for summer resorts,
work was begun in earnest. The house was turned topsy-turvy; the two
brothers attacked the novel enterprise with boyish glee. Alexander,
a born mechanician, set up a huge lathe in one of the bedrooms; a
cabinet-maker was installed in the drawing-room; Caroline, in spite of
secret dismay at such unruly proceedings, lent a hand, and kept meals
going; William directed, inspired, toiled, with the ardour of a man
who had staked his life on the issue. Meanwhile, music could not be
neglected. Practising and choir-training went on; novelties for the
ensuing season were prepared; compositions written, and parts copied.
Then the winter brought the usual round of tuitions and performances,
while all the time mirrors were being ground and polished, tried and
rejected, without intermission. At last, after _two hundred_ failures,
a tolerable reflecting telescope was produced, about five inches in
aperture, and of five and a half feet focal length. The outcome may
seem small for so great an expenditure of pains; but those two hundred
failures made the Octagon Chapel organist an expert, unapproached
and unapproachable, in the construction of specula. With his new
instrument, on March 4th, 1774, he observed the Nebula in Orion; and a
record of this beginning of his astronomical work is still preserved by
the Royal Society.
William Herschel was now, as to age, _in mezzo cammin_. He had numbered
just so many years as had Dante when he began the “Divina Commedia.”
But he had not, like Dante, been thrown off the rails of life. The
rush of a successful professional career was irresistibly carrying him
along. Almost any other man would have had all his faculties absorbed
in it. Herschel’s were only stimulated by the occupations which it
brought. Yet they were of a peculiarly absorbing nature. Music is
the most exclusive of arts. In turning aside, after half a lifetime
spent in its cultivation, to seek his ideal elsewhere, Herschel took
an unparalleled course. And his choice was final. Music was long his
pursuit, astronomy his pastime; a fortunate event enabled him to make
astronomy his pursuit, while keeping music for a pastime.
Yet each demands a totally different kind of training, not only of
the intellect, but of the senses. From his earliest childhood William
Herschel’s nerves and brain had been specially educated to discriminate
impressions of sound, and his muscles to the peculiar agility needed
for their regulated and delicate production; while, up to the age of
thirty-five, he had used his eyes no more purposefully than other
people. The eye, nevertheless, requires cultivation as much as the ear.
“You must not expect to _see at sight_,” he told Alexander Aubert, of
Loam Pit Hill, in 1782. And he wrote to Sir William Watson: “Seeing is
in some respects an art which must be learnt. Many a night have I been
practising to see, and it would be strange if one did not acquire a
certain dexterity by such constant practice.” A critical observation,
he added, could no more be expected from a novice at the telescope than
a performance of one of Handel’s organ-fugues from a beginner in music.
In this difficult art of vision he rapidly became an adept. Taking into
account the full extent of his powers, the opinion has been expressed,
and can scarcely be contradicted, that he never had an equal.
At midsummer, 1774, Herschel removed from No. 7, New King Street, to a
house situated near Walcot Turnpike, Bath. A grass-plot was attached
to the new residence, and it afforded convenient space for workshops.
For already he designed to “carry improvements in telescopes to their
utmost extent,” and “to leave no spot of the heavens unvisited.” An
unprecedented ambition! No son of Adam had ever before entertained
the like. To search into the recesses of space, to sound its depths,
to dredge up from them their shining contents, to classify these, to
investigate their nature, and trace their mutual relations, was what he
proposed to do, having first provided the requisite optical means. All
this in the intervals of professional toils, with no resources except
those supplied by his genius and ardour, with no experience beyond that
painfully gained during the progress of his gigantic task.
Since the time of Huygens, no systematic attempt had been made to add
to the power of the telescope. For the study of the planetary surfaces,
upon which he and his contemporaries were mainly intent, such addition
was highly desirable. But Newton’s discovery profoundly modified the
aims of astronomers. Their essential business then became that of
perfecting the theories of the heavenly bodies. Whether or not they
moved in perfect accordance with the law of gravitation was the crucial
question of the time. Newton’s generalisation was on its trial. Now and
again it almost seemed as if about to fail. But difficulties arose only
to be overcome, and before the eighteenth century closed the superb
mechanism of the planetary system was elucidated. Working flexibly
under the control of a single dominant force, it was shown to possess a
self-righting power which secured its indefinite duration. Imperishable
as the temple of Poseidon, it might be swayed by disturbances, but
could not be overthrown.
The two fundamental conclusions--that the Newtonian law is universally
valid, and that the solar system is a stable structure--were reached
by immense and sustained labours. Their establishment was due, in the
main, to the mathematical genius of Clairaut, D’Alembert, Lagrange,
and Laplace. But refined analysis demands refined data; hence the need
for increased accuracy of observation grew continually more urgent.
Attention was accordingly concentrated upon measuring, with the utmost
exactitude, the places at determinate epochs of the heavenly bodies.
The one thing needful was to learn the “when” and “where” of each of
them--that is, to obtain such information as the transit-instrument is
adapted to give. In this way the deviations of the moon and planets
from their calculated courses became known; and upon the basis of
these “errors” improved theories were built, then again compared with
corrected observations.
For these ends, large telescopes would have been useless. They were
not, however, those that Herschel had in view. The _nature_ of the orbs
around us, not their motions, formed the subject of his inquiries,
with which modern descriptive astronomy virtually originated. He was,
moreover, the founder of sidereal astronomy. The stars had, until
his career began, received little _primary_ attention. They were
regarded and observed simply as reference-points by which to track the
movements of planets, comets, and the moon. Indispensable for fiducial
purposes, they almost escaped consideration for themselves. They were,
indeed, thought to lie beyond the reach of effective investigation.
Only the outbursts of temporary stars, and the fluctuations of two
or three periodical ones, had roused special interest, and seemed
deserving of particular inquiry.
Of the dim objects called “nebulæ,” Halley had counted up half a
dozen in 1714; Lacaille compiled a list of forty-two at the Cape,
in 1752–55; and Messier published at Paris, in 1771, a catalogue of
forty-five, enlarged to one hundred and three in 1781. He tabulated,
only to rid himself of embarrassments from them. For he was _by trade_
a comet-hunter, and, until he hit upon this expedient, had been much
harassed in its exercise by mistakes of identity.
But Herschel did not merely “pick up;” he explored. This was what no
one before him had thought of doing. A “review of the heavens” was a
complete novelty. The magnificence of the idea, which was rooted in his
mind from the start, places him apart from, and above, all preceding
observers.
To its effective execution telescopic development was essential.
The two projects of optical improvement and of sidereal scrutiny
went together. The skies could be fathomed, if at all, only by means
of light-collecting engines of unexampled power. Rays enfeebled by
distance should be rendered effective by concentration. Stratum after
stratum of bodies--
“Clusters and beds of worlds, and bee-like swarms
Of suns and starry streams,”
previously unseen, and even unsuspected, might, by the strong focussing
of their feebly-surviving rays, be brought to human cognisance. The
contemplated “reviews” would then be complete just in proportion to the
grasp of the instrument used in making them.
The first was scarcely more than a reconnaissance. It was made in
1775, with a small reflector of the Newtonian make.[A] Its upshot was
to impress him with the utter disproportion between his daring plans
and the means as yet at his disposal. Speculum-casting accordingly
recommenced with fresh vigour. Seven- and ten-foot mirrors were
succeeded by others of twelve, and even of twenty feet focal length.
The finishing of them was very laborious. It was at that time a manual
process, during the course of which the hands could not be removed from
the metal without injury to its figure. One stretch of such work lasted
sixteen hours, Miss Herschel meantime, “by way of keeping him alive,”
putting occasional morsels of food into the diligent polisher’s mouth.
His mode of procedure was to cast and finish many mirrors of each
sort; then to select the best by trial, and repolish the remainder. In
this manner he made, before 1781, “not less than 200 seven-foot, 150
ten-foot, and about 80 twenty-foot mirrors, not to mention those of the
Gregorian form.” Repolishing operations were, moreover, accompanied
by constant improvements, so that each successive speculum tended to
surpass its predecessors.
[A] In “Newtonian” telescopes the image formed by the large
speculum is obliquely reflected from a small plane mirror
to the side of the tube, where it is viewed with an
ordinary eye-piece. With a “Gregorian,” the observer looks
straight forward, the image being thrown back by a little
_concave_ mirror through a central perforation in the
speculum where the eye-piece is fitted.
These absorbing occupations were interrupted by the unwelcome news
that Dietrich, the youngest of the Herschel family, had decamped from
Hanover “with a young idler” like himself. William instantly started
for Holland, where the fugitive was supposed to be about to take
ship for India, but missed his track; and, after having extended his
journey to Hanover to comfort his anxious mother--his father had died
in 1767--returned sadly to Bath. There, to his immense surprise, he
found the scapegrace in strict charge of his sister, “who kept him to
a diet of roasted apples and barley-water.” His ineffectual escapade
had terminated with an attack of illness at Wapping, whither Alexander
Herschel, on learning how matters stood, had posted off to take him in
charge and watch his recovery. Musical occupation was easily procured
for him at Bath, since he was an accomplished violinist--had, indeed,
started on his unprosperous career in the guise of an infant prodigy;
but he threw it up in 1779 and drifted back to Hanover, married a Miss
Reif, and settled down to live out a fairly long term of shiftless,
albeit harmless, existence.
In 1776 William Herschel succeeded Thomas Linley, Sheridan’s
father-in-law, as Director of the Public Concerts at Bath. His duties
in this capacity, while the season lasted, were most onerous. He had to
engage performers, to appease discontents, to supply casual failures,
to write glees and catches expressly adapted to the voices of his
executants, frequently to come forward himself as a soloist on the
hautboy or the harpsichord. The services of his brother Alexander, a
renowned violoncellist, and of his sister, by this time an excellent
singer, were now invaluable to him. Nor for musical purposes solely.
The vision of the skies was never lost sight of, and the struggle
to realise it in conjunction with his sympathetic helpers absorbed
every remnant of time. At meals the only topics of conversation were
mechanical devices for improving success and averting failure. William
ate with a pencil in his hand, and a project in his head. Between the
acts at the theatre, he might be seen running from the harpsichord to
his telescope. After a rehearsal or a morning performance, he would
dash off to the workshop in periwig and lace ruffles, and leave it
but too often with those delicate adjuncts to his attire torn and
pitch-bespattered. Accidents, too, menacing life and limb, were a
consequence of that “uncommon precipitancy which accompanied all his
actions;” but he escaped intact, save for the loss of a finger-nail.
His introduction to the learned world of Bath was thus described by
himself:--
“About the latter end of December, 1779, I happened to be
engaged in a series of observations on the lunar mountains;
and the moon being in front of my house, late in the evening I
brought my seven-feet reflector into the street, and directed
it to the object of my observations. Whilst 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
eye off the telescope, he very politely asked if he might be
permitted to look in, and this being immediately conceded, he
expressed great satisfaction at the view.”
The inquisitive stranger called next morning, and proved to be Dr.
(later Sir William) Watson. He formed on the spot an unalterable
friendship for the moon-struck musician, and introduced him to a
Philosophical Society which held its meetings at his father’s house.
Herschel’s earliest essays were read before it, but they remained
unpublished. His first printed composition appeared in the “Ladies’
Diary” for 1780. It was an answer to a prize question on the vibration
of strings.
The long series of his communications to the Royal Society of London
opened May 11th, 1780, with a discussion of his observations, begun in
October, 1777, of Mira, the variable star in the neck of the Whale. As
to the theory of its changes, he agreed with Keill that they could best
be explained by supposing rotation on an axis to bring a lucid side and
a side obscured by spots alternately into view. A second paper by him
on the Mountains of the Moon was read on the same day. He measured, in
all, about one hundred of these peaks and craters.
In January, 1781, there came an essay stamped with the peculiar impress
of his genius, entitled “Astronomical Observations on the Rotation of
the Planets round their Axes, made with a view to determine whether the
earth’s diurnal motion is perfectly equable.” It embodied an attempt to
apply a definite criterion to the time-keeping of our planet. But the
prospect is exceedingly remote of rating one planet-clock by the other.
Herschel’s methods of inquiry are, however, aptly illustrated in this
curiously original paper. His speculations always invited the control
of facts. If facts were not at hand, he tried somehow to collect them.
The untrammelled play of fancy was no more to his mind than it was to
Newton’s. His ardent scientific imagination was thus, by the sobriety
of his reason, effectively enlisted in the cause of progress.
Herschel began in 1780 his second review of the heavens, using a
seven-foot Newtonian, of 6¼ inches aperture, with a magnifying power
of 227. “For distinctness of vision,” he said, “this instrument is,
perhaps, equal to any that was ever made.” His praise was amply
justified. As he worked his way with it through the constellation
Gemini, on the night of March 13th, 1781, an unprecedented event
occurred. “A new planet swam into his ken.” He did not recognise it as
such. He could only be certain that it was not a fixed star. His keen
eye, armed with a perfect telescope, discerned at once that the object
had a disc; and the application of higher powers showed the disc to be
a substantial reality. The stellar “patines of bright gold” will not
stand this test. Being of purely optical production, they gain nothing
by magnification.
At that epoch new planets had not yet begun to be found by the dozen.
Five, besides the earth, had been known from the remotest antiquity.
Five, and no more, seemed to have a prescriptive right to exist. The
boundaries of the solar system were of immemorial establishment. It was
scarcely conceivable that they should need to be enlarged. The notion
did not occur to Herschel. His discovery was modestly imparted to the
Royal Society as “An Account of a Comet.” He had, indeed, noticed
that the supposed comet moved in planetary fashion from west to east,
and very near the ecliptic; and, after a few months, its true nature
was virtually proved by Lexell of St. Petersburg. On November 28th,
Herschel measured, with his freshly-invented “lamp-micrometer,” the
diameter of this “singular star;” and it was not until a year later,
November 7th, 1782, that he felt sufficiently sure of its planetary
status to exercise his right of giving it a name. Yet this, in the
long run, he failed to accomplish. The appellation “Georgium Sidus,”
bestowed in honour of his patron, George III., never crossed the
Channel, and has long since gone out of fashion amongst ourselves.
Lalande tried to get the new planet called “Herschel;” but the title
“Uranus,” proposed by Bode, of Berlin, was the “fittest,” and survived.
This discovery made the turning-point of Herschel’s career. It
transformed him from a music-master into an astronomer. Without it
his vast abilities would probably have been in great measure wasted.
No man could long have borne the strain of so arduous a double life
as he was then leading. Relief from it came just in time. It is true
that fame, being often more of a hindrance than a help, brought
embarrassments in its train. In November, 1781, Herschel was compelled
to break the complex web of his engagements at Bath by a journey to
London for the purpose of receiving in person the Copley Medal awarded
to him by the Royal Society, of which body he was, some days later,
elected a Fellow. At home, he was persecuted by admirers; and they
were invariably received with an easy suavity of manner that gave no
hint of preoccupation. Everyone of scientific pretension who visited
Bath sought an interview with the extraordinary man who, by way of
interlude to pressing duties, had built telescopes of unheard-of
power, and performed the startling feat of adding a primary member
to the solar system. Among the few of these callers whose names have
been preserved were Sir Harry Englefield, Sir Charles Blagden, and Dr.
Maskelyne, then, and for thirty years afterwards, Astronomer-Royal.
“With the latter,” Miss Herschel relates, “he (William) was engaged
in a long conversation which to me sounded like quarrelling, and the
first words my brother said after he was gone were, ‘That is a devil
of a fellow!’” The phrase was doubtless meant as a sign of regard, for
the acquaintance thus begun ripened into cordial intimacy. And William
Herschel never lost or forgot a friend.
As regards music alone, the winter of 1781–82 was an exceptionally busy
one. He had arranged to conduct, jointly with Rauzzini, a Roman singer
and composer, a series of oratorios; undertaking, besides, pecuniary
responsibilities which turned out little to his advantage. The labour,
vexation, and disappointment involved in carrying out this unlucky plan
can readily be imagined. But neither the pressure of business, nor
the distractions of celebrity, checked the ardour of his scientific
advance. The review which afforded him the discovery of Uranus, and the
materials for his first catalogue of 269 double stars, was completed
in 1781; and a third, made with the same beautiful instrument, bearing
the high magnifying power of 460, was promptly begun. This had for one
of its special objects the ascertainment of possible changes in the
heavens since Flamsteed’s time; and in the course of it many thousands
of stars came under scrutiny, directed to ascertain their magnitude and
colour, singleness or duplicity, hazy or defined aspect.
The first of Herschel’s _effective_ twenty-foot telescopes was erected
at 19, New King Street, in the summer of 1781. Enclosing a mirror
twelve inches in diameter, it far surpassed any seeing-machine that had
ever existed in the world. Yet its maker regarded it as only marking
a step in his upward progress. A speculum of thirty-feet focus was
the next object of his ambition. For its achievement no amount of
exertion was counted too great. Its composition was regulated by fresh
experiments on various alloys of copper and tin. Its weight and shape
were again and again calculated, and the methods appropriate to its
production earnestly discussed. “I saw nothing else,” Caroline Herschel
tells us, “and heard nothing else talked of but these things when my
brothers were together.”[B]
[B] In borrowing Miss Herschel’s lively narratives and
comments, some obvious slips in grammar and construction
have been corrected. Quotations, too, from the writings
of Sir William and Sir John Herschel are often slightly
abridged.
“The mirror,” she continues, “was to be cast in a mould of loam
prepared from horse-dung, of which an immense quantity was to be
pounded in a mortar and sifted through a fine sieve. It was an endless
piece of work, and served me for many an hour’s exercise; and Alex
frequently took his turn at it, for we were all eager to do something
towards the great undertaking. Even Sir William Watson would sometimes
take the pestle from me when he found me in the work-room.”
The matter was never out of the master’s thoughts. “If a minute could
but be spared in going from one scholar to another, or giving one the
slip, he called at home to see how the men went on with the furnace,
which was built in a room below, even with the garden.”
At last, the concert season being over, and everything in readiness
for the operation of casting, “the metal,” we hear from the same
deeply-interested eyewitness, “was in the furnace; but, unfortunately,
it began to leak at the moment when ready for pouring, and both my
brothers, and the caster with his men, were obliged to run out at
opposite doors, for the stone flooring, which ought to have been taken
up, flew about in all directions, as high as the ceiling. My poor
brother William fell, exhausted with heat and exertion, on a heap of
brickbats. Before the second casting was attempted, everything which
could ensure success had been attended to, and a very perfect metal was
found in the mould, which had cracked in the cooling.”
This second failure terminated the enterprise. Not that it was
abandoned as hopeless, but because of a total change in the current of
affairs. Herschel’s fame had stirred the royal curiosity, and rumours
had now and again reached Bath that he was to be sent for to court. In
the spring of 1782 the actual mandate arrived; and on May 8th, leaving
his pupils and his projects to shift for themselves, he set out for
London. He carried with him his favourite seven-foot reflector, and all
the apparatus necessary for viewing double stars and other objects of
interest. On May 25th he wrote to his sister:--
“I have had an audience of His Majesty this morning, and met with a
very gracious reception. I presented him with the drawing of the solar
system, and had the honour of explaining it to him and the Queen. My
telescope is in three weeks’ time to go to Richmond, and meanwhile
to be put up at Greenwich.... Tell Alexander that everything looks
very like as if I were to stay here. The King enquired after him, and
after my great speculum. He also gave me leave to come and hear the
Griesbachs (Herschel’s nephews) play at the private concert which he
has every evening.... All my papers are printing, and are allowed to
be very valuable. You see, Lina, I tell you all these things. You
know vanity is not my foible, therefore I need not fear your censure.
Farewell.”
His next letter is dated June 3rd, 1782. “I pass my time,” he informed
“Lina,” “between Greenwich and London agreeably enough, but am rather
at a loss for work that I like. Company is not always pleasing, and I
would much rather be polishing a speculum. Last Friday I was at the
King’s concert to hear George play. The King spoke to me as soon as he
saw me, and kept me in conversation for half an hour. He asked George
to play a solo-concerto on purpose that I might hear him.... I am
introduced to the best company. To-morrow I dine at Lord Palmerston’s,
next day with Sir Joseph Banks, etc. Among opticians and astronomers
nothing now is talked of but _what they call_ my great discoveries.
Alas! this shows how far they are behind, when such trifles as I have
seen and done are called _great_. Let me but get at it again! I will
make such telescopes and see such things--that is, I will endeavour to
do so.”
A comparison of his telescope with those at the Royal Observatory
showed its striking superiority, although among them was one of Short’s
famous Gregorians, of 9½ inches aperture. It had thus a reflecting
surface above twice that of Herschel’s seven-foot, the competition
with which was nevertheless so disastrous to its reputation that Dr.
Maskelyne fell quite out of conceit with it, and doubted whether it
_deserved_ the new stand constructed for it on the model of Herschel’s.
In the midst of these scientific particulars, we hear incidentally that
influenza was then so rife in London that “hardly one single person”
escaped an attack.
On July 2nd he made his first appearance as showman of the heavens to
royalty. The scene of the display was Buckingham House (now Buckingham
Palace). “It was a very fine evening,” he wrote to his sister. “My
instrument gave general satisfaction. The King has very good eyes, and
enjoys observations with telescopes exceedingly.”
Next night, the King and Queen being absent at Kew, the Princesses
desired an exhibition. But, since they objected to damp grass, the
telescope, Herschel says, “was moved into the Queen’s apartments, and
we waited some time in hopes of seeing Jupiter or Saturn. Meanwhile
I showed the Princesses and several other ladies the speculum, the
micrometers, the movements of the telescope, and other things that
seemed to excite their curiosity. When the evening appeared to be
totally unpromising, I proposed an artificial Saturn as an object,
since we could not have the real one. I had beforehand prepared this
little piece, as I guessed by the appearance of the weather in the
afternoon we should have no stars to look at. This being accepted with
great pleasure, I had the lamps lighted up, which illuminated the
picture of a Saturn (cut out in pasteboard) at the bottom of the garden
wall. The effect was fine, and so natural that the best astronomer
might have been deceived. Their royal highnesses seemed to be much
pleased with the artifice.” From a somewhat prolonged conversation,
he judged them to be “extremely well instructed,” and “most amiable
characters.”
Shortly afterwards Herschel received the appointment of royal
astronomer, with the modest salary of £200 a year. “Never,” exclaimed
Sir William Watson on being made acquainted with its amount, “bought
monarch honour so cheap!” The provision was assuredly not munificent;
yet it sufficed to rescue a great man from submergence under the hard
necessities of existence. The offer was critically timed. It was made
precisely when teaching and concert-giving had come to appear an
“intolerable waste of time” to one fired with a visionary passion.
“Stout Cortes” staring at the Pacific, Ulysses starting from Ithaca to
“sail beyond the sunset,” were not more eager for experience of the
Unknown.