Great Astronomers
by
R. S. Ball
Part 2 out of 5
common-sense!
There can be no doubt that a special significance attached to the new
discovery at this particular epoch in the history of science. It
must be remembered that in those days the doctrine of Copernicus,
declaring that the sun, and not the earth, was the centre of the
system, that the earth revolved on its axis once a day, and that it
described a mighty circle round the sun once a year, had only
recently been promulgated. This new view of the scheme of nature had
been encountered with the most furious opposition. It may possibly
have been that Galileo himself had not felt quite confident in the
soundness of the Copernican theory, prior to the discovery of the
satellites of Jupiter. But when a picture was there exhibited in
which a number of relatively small globes were shown to be revolving
around a single large globe in the centre, it seemed impossible not
to feel that the beautiful spectacle so displayed was an emblem of
the relations of the planets to the sun. It was thus made manifest
to Galileo that the Copernican theory of the planetary system must be
the true one. The momentous import of this opinion upon the future
welfare of the great philosopher will presently appear.
It would seem that Galileo regarded his residence at Padua as a state
of undesirable exile from his beloved Tuscany. He had always a
yearning to go back to his own country and at last the desired
opportunity presented itself. For now that Galileo's fame had become
so great, the Grand Duke of Tuscany desired to have the philosopher
resident at Florence, in the belief that he would shed lustre on the
Duke's dominions. Overtures were accordingly made to Galileo, and
the consequence was that in 1616 we find him residing at Florence,
bearing the title of Mathematician and Philosopher to the Grand Duke.
Two daughters, Polissena and Virginia, and one son, Vincenzo, had
been born to Galileo in Padua. It was the custom in those days that
as soon as the daughter of an Italian gentleman had grown up, her
future career was somewhat summarily decided. Either a husband was
to be forthwith sought out, or she was to enter the convent with the
object of taking the veil as a professed nun. It was arranged that
the two daughters of Galileo, while still scarcely more than
children, should both enter the Franciscan convent of St. Matthew, at
Arcetri. The elder daughter Polissena, took the name of Sister Maria
Celeste, while Virginia became Sister Arcangela. The latter seems to
have been always delicate and subject to prolonged melancholy, and
she is of but little account in the narrative of the life of
Galileo. But Sister Maria Celeste, though never leaving the convent,
managed to preserve a close intimacy with her beloved father. This
was maintained only partly by Galileo's visits, which were very
irregular and were, indeed, often suspended for long intervals. But
his letters to this daughter were evidently frequent and
affectionate, especially in the latter part of his life. Most
unfortunately, however, all his letters have been lost. There are
grounds for believing that they were deliberately destroyed when
Galileo was seized by the Inquisition, lest they should have been
used as evidence against him, or lest they should have compromised
the convent where they were received. But Sister Maria Celeste's
letters to her father have happily been preserved, and most touching
these letters are. We can hardly read them without thinking how the
sweet and gentle nun would have shrunk from the idea of their
publication.
Her loving little notes to her "dearest lord and father," as she used
affectionately to call Galileo, were almost invariably accompanied by
some gift, trifling it may be, but always the best the poor nun had
to bestow. The tender grace of these endearing communications was
all the more precious to him from the fact that the rest of Galileo's
relatives were of quite a worthless description. He always
acknowledged the ties of his kindred in the most generous way, but
their follies and their vices, their selfishness and their
importunities, were an incessant source of annoyance to him, almost
to the last day of his life.
On 19th December, 1625, Sister Maria Celeste writes:--
"I send two baked pears for these days of vigil. But as the greatest
treat of all, I send you a rose, which ought to please you extremely,
seeing what a rarity it is at this season; and with the rose you must
accept its thorns, which represent the bitter passion of our Lord,
whilst the green leaves represent the hope we may entertain that
through the same sacred passion we, having passed through the
darkness of the short winter of our mortal life, may attain to the
brightness and felicity of an eternal spring in heaven."
When the wife and children of Galileo's shiftless brother came to
take up their abode in the philosopher's home, Sister Maria Celeste
feels glad to think that her father has now some one who, however
imperfectly, may fulfil the duty of looking after him. A graceful
note on Christmas Eve accompanies her little gifts. She hopes that--
"In these holy days the peace of God may rest on him and all the
house. The largest collar and sleeves I mean for Albertino, the
other two for the two younger boys, the little dog for baby, and the
cakes for everybody, except the spice-cakes, which are for you.
Accept the good-will which would readily do much more."
The extraordinary forbearance with which Galileo continually placed
his time, his purse, and his influence at the service of those who
had repeatedly proved themselves utterly unworthy of his countenance,
is thus commented on by the good nun.--
"Now it seems to me, dearest lord and father, that your lordship is
walking in the right path, since you take hold of every occasion that
presents itself to shower continual benefits on those who only repay
you with ingratitude. This is an action which is all the more
virtuous and perfect as it is the more difficult."
When the plague was raging in the neighbourhood, the loving
daughter's solicitude is thus shown:--
"I send you two pots of electuary as a preventive against the
plague. The one without the label consists of dried figs, walnuts,
rue, and salt, mixed together with honey. A piece of the size of a
walnut to be taken in the morning, fasting, with a little Greek
wine."
The plague increasing still more, Sister Maria Celeste obtained with
much difficulty, a small quantity of a renowned liqueur, made by
Abbess Ursula, an exceptionally saintly nun. This she sends to her
father with the words:--
"I pray your lordship to have faith in this remedy. For if you have
so much faith in my poor miserable prayers, much more may you have in
those of such a holy person; indeed, through her merits you may feel
sure of escaping all danger from the plague."
Whether Galileo took the remedy we do not know, but at all events
he escaped the plague.
[PLATE: THE VILLA ARCETRI.
Galileo's residence, where Milton visited him.]
From Galileo's new home in Florence the telescope was again directed
to the skies, and again did astounding discoveries reward the
astronomer's labours. The great success which he had met with in
studying Jupiter naturally led Galileo to look at Saturn. Here he
saw a spectacle which was sufficiently amazing, though he failed to
interpret it accurately. It was quite manifest that Saturn did not
exhibit a simple circular disc like Jupiter, or like Mars. It seemed
to Galileo as if the planet consisted of three bodies, a large globe
in the centre, and a smaller one on each side. The enigmatical
nature of the discovery led Galileo to announce it in an enigmatical
manner. He published a string of letters which, when duly
transposed, made up a sentence which affirmed that the planet Saturn
was threefold. Of course we now know that this remarkable appearance
of the planet was due to the two projecting portions of the ring.
With the feeble power of Galileo's telescope, these seemed merely
like small globes or appendages to the large central body.
The last Of Galileo's great astronomical discoveries related to the
libration of the moon. I think that the detection of this phenomenon
shows his acuteness of observation more remarkably than does any one
of his other achievements with the telescope. It is well known that
the moon constantly keeps the same face turned towards the earth.
When, however, careful measurements have been made with regard to the
spots and marks on the lunar surface, it is found that there is a
slight periodic variation which permits us to see now a little to the
east or to the west, now a little to the north or to the south of
the average lunar disc.
But the circumstances which make the career of Galileo so especially
interesting from the biographer's point of view, are hardly so much
the triumphs that he won as the sufferings that he endured. The
sufferings and the triumphs were, however, closely connected, and it
is fitting that we should give due consideration to what was perhaps
the greatest drama in the history of science.
On the appearance of the immortal work of Copernicus, in which it was
taught that the earth rotated on its axis, and that the earth, like
the other planets, revolved round the sun, orthodoxy stood aghast.
The Holy Roman Church submitted this treatise, which bore the name
"De Revolutionibus Orbium Coelestium," to the Congregation of the
Index. After due examination it was condemned as heretical in 1615.
Galileo was suspected, on no doubt excellent grounds, of entertaining
the objectionable views of Copernicus. He was accordingly privately
summoned before Cardinal Bellarmine on 26th February 1616, and duly
admonished that he was on no account to teach or to defend the
obnoxious doctrines. Galileo was much distressed by this
intimation. He felt it a serious matter to be deprived of the
privilege of discoursing with his friends about the Copernican
system, and of instructing his disciples in the principles of the
great theory of whose truth he was perfectly convinced. It pained
him, however, still more to think, devout Catholic as he was, that
such suspicions of his fervent allegiance to his Church should ever
have existed, as were implied by the words and monitions of Cardinal
Bellarmine.
In 1616, Galileo had an interview with Pope Paul V., who received the
great astronomer very graciously, and walked up and down with him in
conversation for three-quarters of an hour. Galileo complained to
his Holiness of the attempts made by his enemies to embarrass him
with the authorities of the Church, but the Pope bade him be
comforted. His Holiness had himself no doubts of Galileo's
orthodoxy, and he assured him that the Congregation of the Index
should give Galileo no further trouble so long as Paul V. was in the
chair of St. Peter.
On the death of Paul V. in 1623, Maffeo Barberini was elected Pope,
as Urban VIII. This new Pope, while a cardinal, had been an intimate
friend of Galileo's, and had indeed written Latin verses in praise of
the great astronomer and his discoveries. It was therefore not
unnatural for Galileo to think that the time had arrived when, with
the use of due circumspection, he might continue his studies and his
writings, without fear of incurring the displeasure of the Church.
Indeed, in 1624, one of Galileo's friends writing from Rome, urges
Galileo to visit the city again, and added that--
"Under the auspices of this most excellent, learned, and benignant
Pontiff, science must flourish. Your arrival will be welcome to his
Holiness. He asked me if you were coming, and when, and in short, he
seems to love and esteem you more than ever."
The visit was duly paid, and when Galileo returned to Florence, the
Pope wrote a letter from which the following is an extract,
commanding the philosopher to the good offices of the young
Ferdinand, who had shortly before succeeded his father in the Grand
Duchy of Tuscany.
"We find in Galileo not only literary distinction, but also the love
of piety, and he is also strong in those qualities by which the
pontifical good-will is easily obtained. And now, when he has been
brought to this city to congratulate us on our elevation, we have
very lovingly embraced him; nor can we suffer him to return to the
country whither your liberality calls him, without an ample provision
of pontifical love. And that you may know how dear he is to us, we
have willed to give him this honourable testimonial of virtue and
piety. And we further signify that every benefit which you shall
confer upon him, imitating or even surpassing your father's
liberality, will conduce to our gratification."
The favourable reception which had been accorded to him by Pope Urban
VIII. seems to have led Galileo to expect that there might be some
corresponding change in the attitude of the Papal authorities on the
great question of the stability of the earth. He accordingly
proceeded with the preparation of the chief work of his life, "The
Dialogue of the two Systems." It was submitted for inspection by the
constituted authorities. The Pope himself thought that, if a few
conditions which he laid down were duly complied with, there could be
no objection to the publication of the work. In the first place, the
title of the book was to be so carefully worded as to show plainly
that the Copernican doctrine was merely to be regarded as an
hypothesis, and not as a scientific fact. Galileo was also
instructed to conclude the book with special arguments which had been
supplied by the Pope himself, and which appeared to his Holiness to
be quite conclusive against the new doctrine of Copernicus.
Formal leave for the publication of the Dialogue was then given to
Galileo by the Inquisitor General, and it was accordingly sent to the
press. It might be thought that the anxieties of the astronomer
about his book would then have terminated. As a matter of fact, they
had not yet seriously begun. Riccardi, the Master of the Sacred
Palace, having suddenly had some further misgivings, sent to Galileo
for the manuscript while the work was at the printer's, in order that
the doctrine it implied might be once again examined. Apparently,
Riccardi had come to the conclusion that he had not given the matter
sufficient attention, when the authority to go to press had been
first and, perhaps, hastily given. Considerable delay in the issue
of the book was the result of these further deliberations. At last,
however, in June, 1632, Galileo's great work, "The Dialogue of the
two Systems," was produced for the instruction of the world, though
the occasion was fraught with ruin to the immortal author.
[PLATE: FACSIMILE SKETCH OF LUNAR SURFACE BY GALILEO.]
The book, on its publication, was received and read with the greatest
avidity. But presently the Master of The Sacred Palace found reason
to regret that he had given his consent to its appearance. He
accordingly issued a peremptory order to sequestrate every copy in
Italy. This sudden change in the Papal attitude towards Galileo
formed the subject of a strong remonstrance addressed to the Roman
authorities by the Grand Duke of Tuscany. The Pope himself seemed to
have become impressed all at once with the belief that the work
contained matter of an heretical description. The general
interpretation put upon the book seems to have shown the authorities
that they had mistaken its true tendency, notwithstanding the fact
that it had been examined again and again by theologians deputed for
the duty. To the communication from the Grand Duke the Pope returned
answer, that he had decided to submit the book to a congregation of
"learned, grave, and saintly men," who would weigh every word in it.
The views of his Holiness personally on the subject were expressed in
his belief that the Dialogue contained the most perverse matter that
could come into a reader's hands.
The Master of the Sacred Palace was greatly blamed by the authorities
for having given his sanction to its issue. He pleaded that the book
had not been printed in the precise terms of the original manuscript
which had been submitted to him. It was also alleged that Galileo
had not adhered to his promise of inserting properly the arguments
which the Pope himself had given in support of the old and orthodox
view. One of these had, no doubt, been introduced, but, so far from
mending Galileo's case, it had made matters really look worse for the
poor philosopher. The Pope's argument had been put into the mouth of
one of the characters in the Dialogue named "Simplicio." Galileo's
enemies maintained that by adopting such a method for the expression
of his Holiness's opinion, Galileo had intended to hold the Pope
himself up to ridicule. Galileo's friends maintained that nothing
could have been farther from his intention. It seems, however,
highly probable that the suspicions thus aroused had something to say
to the sudden change of front on the part of the Papal authorities.
On 1st October, 1632, Galileo received an order to appear before the
Inquisition at Rome on the grave charge of heresy. Galileo, of
course, expressed his submission, but pleaded for a respite from
compliance with the summons, on the ground of his advanced age and
his failing health. The Pope was, however, inexorable; he said that
he had warned Galileo of his danger while he was still his friend.
The command could not be disobeyed. Galileo might perform the
journey as slowly as he pleased, but it was imperatively necessary
for him to set forth and at once.
On 20th January, 1633, Galileo started on his weary journey to Rome,
in compliance with this peremptory summons. On 13th February he was
received as the guest of Niccolini, the Tuscan ambassador, who had
acted as his wise and ever-kind friend throughout the whole affair.
It seemed plain that the Holy Office were inclined to treat Galileo
with as much clemency and consideration as was consistent with the
determination that the case against him should be proceeded with to
the end. The Pope intimated that in consequence of his respect for
the Grand Duke of Tuscany he should permit Galileo to enjoy the
privilege, quite unprecedented for a prisoner charged with heresy, of
remaining as an inmate in the ambassador's house. He ought,
strictly, to have been placed in the dungeons of the Inquisition.
When the examination of the accused had actually commenced, Galileo
was confined, not, indeed, in the dungeons, but in comfortable rooms
at the Holy Office.
By the judicious and conciliatory language of submission which
Niccolini had urged Galileo to use before the Inquisitors, they were
so far satisfied that they interceded with the Pope for his release.
During the remainder of the trial Galileo was accordingly permitted
to go back to the ambassador's, where he was most heartily welcomed.
Sister Maria Celeste, evidently thinking this meant that the whole
case was at an end, thus expresses herself:--
"The joy that your last dear letter brought me, and the having to
read it over and over to the nuns, who made quite a jubilee on
hearing its contents, put me into such an excited state that at last
I got a severe attack of headache."
In his defence Galileo urged that he had already been acquitted in
1616 by Cardinal Bellarmine, when a charge of heresy was brought
against him, and he contended that anything he might now have done,
was no more than he had done on the preceding occasion, when the
orthodoxy of his doctrines received solemn confirmation. The
Inquisition seemed certainly inclined to clemency, but the Pope was
not satisfied. Galileo was accordingly summoned again on the 21st
June. He was to be threatened with torture if he did not forthwith
give satisfactory explanations as to the reasons which led him to
write the Dialogue. In this proceeding the Pope assured the Tuscan
ambassador that he was treating Galileo with the utmost consideration
possible in consequence of his esteem and regard for the Grand Duke,
whose servant Galileo was. It was, however, necessary that some
exemplary punishment be meted out to the astronomer, inasmuch as by
the publication of the Dialogue he had distinctly disobeyed the
injunction of silence laid upon him by the decree of 1616. Nor was
it admissible for Galileo to plead that his book had been sanctioned
by the Master of the Sacred College, to whose inspection it had been
again and again submitted. It was held, that if the Master of the
Sacred College had been unaware of the solemn warning the philosopher
had already received sixteen years previously, it was the duty of
Galileo to have drawn his attention to that fact.
On the 22nd June, 1633, Galileo was led to the great hall of the
Inquisition, and compelled to kneel before the cardinals there
assembled and hear his sentence. In a long document, most
elaborately drawn up, it is definitely charged against Galileo that,
in publishing the Dialogue, he committed the essentially grave error
of treating the doctrine of the earth's motion as open to
discussion. Galileo knew, so the document affirmed, that the Church
had emphatically pronounced this notion to be contrary to Holy Writ,
and that for him to consider a doctrine so stigmatized as having any
shadow of probability in its favour was an act of disrespect to the
authority of the Church which could not be overlooked. It was also
charged against Galileo that in his Dialogue he has put the strongest
arguments into the mouth, not of those who supported the orthodox
doctrine, but of those who held the theory as to the earth's motion
which the Church had so deliberately condemned.
After due consideration of the defence made by the prisoner, it was
thereupon decreed that he had rendered himself vehemently suspected
of heresy by the Holy Office, and in consequence had incurred all the
censures and penalties of the sacred canons, and other decrees
promulgated against such persons. The graver portion of these
punishments would be remitted, if Galileo would solemnly repudiate
the heresies referred to by an abjuration to be pronounced by him in
the terms laid down.
At the same time it was necessary to mark, in some emphatic manner,
the serious offence which had been committed, so that it might serve
both as a punishment to Galileo and as a warning to others. It was
accordingly decreed that he should be condemned to imprisonment in
the Holy Office during the pleasure of the Papal authorities, and
that he should recite once a week for three years the seven
Penitential Psalms.
Then followed that ever-memorable scene in the great hall of the
Inquisition, in which the aged and infirm Galileo, the inventor of
the telescope and the famous astronomer, knelt down to abjure before
the most eminent and reverend Lords Cardinal, Inquisitors General
throughout the Christian Republic against heretical depravity. With
his hands on the Gospels, Galileo was made to curse and detest the
false opinion that the sun was the centre of the universe and
immovable, and that the earth was not the centre of the same, and
that it moved. He swore that for the future he will never say nor
write such things as may bring him under suspicion, and that if he
does so he submits to all the pains and penalties of the sacred
canons. This abjuration was subsequently read in Florence before
Galileo's disciples, who had been specially summoned to attend.
It has been noted that neither on the first occasion, in 1616, nor on
the second in 1633, did the reigning Pope sign the decrees concerning
Galileo. The contention has accordingly been made that Paul V. and
Urban VIII. are both alike vindicated from any technical
responsibility for the attitude of the Romish Church towards the
Copernican doctrines. The significance of this circumstance has been
commented on in connection with the doctrine of the infallibility of
the Pope.
We can judge of the anxiety felt by Sister Maria Celeste about her
beloved father during these terrible trials. The wife of the
ambassador Niccolini, Galileo's steadfast friend, most kindly wrote
to give the nun whatever quieting assurances the case would permit.
There is a renewed flow of these touching epistles from the daughter
to her father. Thus she sends word--
"The news of your fresh trouble has pierced my soul with grief all
the more that it came quite unexpectedly."
And again, on hearing that he had been permitted to leave Rome,
she writes--
"I wish I could describe the rejoicing of all the mothers and sisters
on hearing of your happy arrival at Siena. It was indeed most
extraordinary. On hearing the news the Mother Abbess and many of the
nuns ran to me, embracing me and weeping for joy and tenderness."
The sentence of imprisonment was at first interpreted leniently by
the Pope. Galileo was allowed to reside in qualified durance in the
archbishop's house at Siena. Evidently the greatest pain that he
endured arose from the forced separation from that daughter, whom he
had at last learned to love with an affection almost comparable with
that she bore to him. She had often told him that she never had any
pleasure equal to that with which she rendered any service to her
father. To her joy, she discovers that she can relieve him from the
task of reciting the seven Penitential Psalms which had been imposed
as a Penance:--
"I began to do this a while ago," she writes, "and it gives me much
pleasure. First, because I am persuaded that prayer in obedience to
Holy Church must be efficacious; secondly, in order to save you the
trouble of remembering it. If I had been able to do more, most
willingly would I have entered a straiter prison than the one I live
in now, if by so doing I could have set you at liberty."
[PLATE: CREST OF GALILEO'S FAMILY.]
Sister Maria Celeste was gradually failing in health, but the great
privilege was accorded to her of being able once again to embrace her
beloved lord and master. Galileo had, in fact, been permitted to
return to his old home; but on the very day when he heard of his
daughter's death came the final decree directing him to remain in his
own house in perpetual solitude.
Amid the advancing infirmities of age, the isolation from friends,
and the loss of his daughter, Galileo once again sought consolation
in hard work. He commenced his famous dialogue on Motion. Gradually,
however, his sight began to fail, and blindness was at last added to
his other troubles. On January 2nd, 1638, he writes to Diodati:--
"Alas, your dear friend and servant, Galileo, has been for the last
month perfectly blind, so that this heaven, this earth, this universe
which I by my marvellous discoveries and clear demonstrations have
enlarged a hundred thousand times beyond the belief of the wise men
of bygone ages, henceforward is for me shrunk into such a small space
as is filled by my own bodily sensations."
But the end was approaching--the great philosopher, was attacked by
low fever, from which he died on the 8th January, 1643.
KEPLER.
While the illustrious astronomer, Tycho Brahe, lay on his death-bed,
he had an interview which must ever rank as one of the important
incidents in the history of science. The life of Tycho had been
passed, as we have seen, in the accumulation of vast stores of
careful observations of the positions of the heavenly bodies. It was
not given to him to deduce from his splendid work the results to
which they were destined to lead. It was reserved for another
astronomer to distil, so to speak, from the volumes in which Tycho's
figures were recorded, the great truths of the universe which those
figures contained. Tycho felt that his work required an interpreter,
and he recognised in the genius of a young man with whom he was
acquainted the agent by whom the world was to be taught some of the
great truths of nature. To the bedside of the great Danish
astronomer the youthful philosopher was summoned, and with his last
breath Tycho besought of him to spare no labour in the performance of
those calculations, by which alone the secrets of the movements of
the heavens could be revealed. The solemn trust thus imposed was
duly accepted, and the man who accepted it bore the immortal name of
Kepler.
Kepler was born on the 27th December, 1571, at Weil, in the Duchy of
Wurtemberg. It would seem that the circumstances of his childhood
must have been singularly unhappy. His father, sprung from a
well-connected family, was but a shiftless and idle adventurer; nor
was the great astronomer much more fortunate in his other parent. His
mother was an ignorant and ill-tempered woman; indeed, the
ill-assorted union came to an abrupt end through the desertion of the
wife by her husband when their eldest son John, the hero of our
present sketch, was eighteen years old. The childhood of this lad,
destined for such fame, was still further embittered by the
circumstance that when he was four years old he had a severe attack
of small-pox. Not only was his eyesight permanently injured, but
even his constitution appears to have been much weakened by this
terrible malady.
It seems, however, that the bodily infirmities of young John Kepler
were the immediate cause of his attention being directed to the
pursuit of knowledge. Had the boy been fitted like other boys for
ordinary manual work, there can be hardly any doubt that to manual
work his life must have been devoted. But, though his body was
feeble, he soon gave indications of the possession of considerable
mental power. It was accordingly thought that a suitable sphere for
his talents might be found in the Church which, in those days, was
almost the only profession that afforded an opening for an
intellectual career. We thus find that by the time John Kepler was
seventeen years old he had attained a sufficient standard of
knowledge to entitle him to admission on the foundation of the
University at Tubingen.
In the course of his studies at this institution he seems to have
divided his attention equally between astronomy and divinity. It not
unfrequently happens that when a man has attained considerable
proficiency in two branches of knowledge he is not able to see very
clearly in which of the two pursuits his true vocation lies. His
friends and onlookers are often able to judge more wisely than he
himself can do as to which Of the two lines it would be better for
him to pursue. This incapacity for perceiving the path in which
greatness awaited him, existed in the case of Kepler. Personally, he
inclined to enter the ministry, in which a promising career seemed
open to him. He yielded, however, to friends, who evidently knew him
better than he knew himself, and accepted in 1594, the important
Professorship of astronomy which had been offered to him in the
University of Gratz.
It is difficult for us in these modern days to realise the somewhat
extraordinary duties which were expected from an astronomical
professor in the sixteenth century. He was, of course, required to
employ his knowledge of the heavens in the prediction of eclipses,
and of the movements of the heavenly bodies generally. This seems
reasonable enough; but what we are not prepared to accept is the
obligation which lay on the astronomers to predict the fates of
nations and the destinies of individuals.
It must be remembered that it was the almost universal belief in
those days, that all the celestial spheres revolved in some
mysterious fashion around the earth, which appeared by far the most
important body in the universe. It was imagined that the sun, the
moon, and the stars indicated, in the vicissitudes of their
movements, the careers of nations and of individuals. Such being the
generally accepted notion, it seemed to follow that a professor who
was charged with the duty of expounding the movements of the heavenly
bodies must necessarily be looked to for the purpose of deciphering
the celestial decrees regarding the fate of man which the heavenly
luminaries were designed to announce.
Kepler threw himself with characteristic ardour into even this
fantastic phase of the labours of the astronomical professor; he
diligently studied the rules of astrology, which the fancies of
antiquity had compiled. Believing sincerely as he did in the
connection between the aspect of the stars and the state of human
affairs, he even thought that he perceived, in the events of his own
life, a corroboration of the doctrine which affirmed the influence of
the planets upon the fate of individuals.
[PLATE: KEPLER'S SYSTEM OF REGULAR SOLIDS.]
But quite independently of astrology there seem to have been many
other delusions current among the philosophers of Kepler's time. It
is now almost incomprehensible how the ablest men of a few centuries
ago should have entertained such preposterous notions, as they did,
with respect to the system of the universe. As an instance of what
is here referred to, we may cite the extraordinary notion which,
under the designation of a discovery, first brought Kepler into
fame. Geometers had long known that there were five, but no more
than five, regular solid figures. There is, for instance, the cube
with six sides, which is, of course, the most familiar of these
solids. Besides the cube there are other figures of four, eight,
twelve, and twenty sides respectively. It also happened that there
were five planets, but no more than five, known to the ancients,
namely, Mercury, Venus, Mars, Jupiter, and Saturn. To Kepler's
lively imaginations this coincidence suggested the idea that the five
regular solids corresponded to the five planets, and a number of
fancied numerical relations were adduced on the subject. The
absurdity of this doctrine is obvious enough, especially when we
observe that, as is now well known, there are two large planets, and
a host of small planets, over and above the magical number of the
regular solids. In Kepler's time, however, this doctrine was so far
from being regarded as absurd, that its announcement was hailed as a
great intellectual triumph. Kepler was at once regarded with
favour. It seems, indeed, to have been the circumstance which
brought him into correspondence with Tycho Brahe. By its means also
he became known to Galileo.
The career of a scientific professor in those early days appears
generally to have been marked by rather more striking vicissitudes
than usually befall a professor in a modern university. Kepler was a
Protestant, and as such he had been appointed to his professorship at
Gratz. A change, however, having taken place in the religious belief
entertained by the ruling powers of the University, the Protestant
professors were expelled. It seems that special influence having
been exerted in Kepler's case on account of his exceptional eminence,
he was recalled to Gratz and reinstated in the tenure of his chair.
But his pupils had vanished, so that the great astronomer was glad to
accept a post offered him by Tycho Brahe in the observatory which the
latter had recently established near Prague.
On Tycho's death, which occurred soon after, an opening presented
itself which gave Kepler the opportunity his genius demanded. He was
appointed to succeed Tycho in the position of imperial mathematician.
But a far more important point, both for Kepler and for science,
was that to him was confided the use of Tycho's observations. It was,
indeed, by the discussion of Tycho's results that Kepler was enabled
to make the discoveries which form such an important part of
astronomical history.
Kepler must also be remembered as one of the first great astronomers
who ever had the privilege of viewing celestial bodies through a
telescope. It was in 1610 that he first held in his hands one of
those little instruments which had been so recently applied to the
heavens by Galileo. It should, however, be borne in mind that the
epoch-making achievements of Kepler did not arise from any telescopic
observations that he made, or, indeed, that any one else made. They
were all elaborately deduced from Tycho's measurements of the
positions of the planets, obtained with his great instruments, which
were unprovided with telescopic assistance.
To realise the tremendous advance which science received from
Kepler's great work, it is to be understood that all the astronomers
who laboured before him at the difficult subject of the celestial
motions, took it for granted that the planets must revolve in
circles. If it did not appear that a planet moved in a fixed circle,
then the ready answer was provided by Ptolemy's theory that the
circle in which the planet did move was itself in motion, so that its
centre described another circle.
When Kepler had before him that wonderful series of observations of
the planet, Mars, which had been accumulated by the extraordinary
skill of Tycho, he proved, after much labour, that the movements of
the planet refused to be represented in a circular form. Nor would
it do to suppose that Mars revolved in one circle, the centre of
which revolved in another circle. On no such supposition could the
movements of the planets be made to tally with those which Tycho had
actually observed. This led to the astonishing discovery of the true
form of a planet's orbit. For the first time in the history of
astronomy the principle was laid down that the movement of a planet
could not be represented by a circle, nor even by combinations of
circles, but that it could be represented by an elliptic path. In
this path the sun is situated at one of those two points in the
ellipse which are known as its foci.
[PLATE: KEPLER.]
Very simple apparatus is needed for the drawing of one of those
ellipses which Kepler has shown to possess such astonishing
astronomical significance. Two pins are stuck through a sheet of
paper on a board, the point of a pencil is inserted in a loop of
string which passes over the pins, and as the pencil is moved round
in such a way as to keep the string stretched, that beautiful curve
known as the ellipse is delineated, while the positions of the pins
indicate the two foci of the curve. If the length of the loop of
string is unchanged then the nearer the pins are together, the
greater will be the resemblance between the ellipse and the circle,
whereas the more the pins are separated the more elongated does the
ellipse become. The orbit of a great planet is, in general, one of
those ellipses which approaches a nearly circular form. It
fortunately happens, however, that the orbit of Mars makes a wider
departure from the circular form than any of the other important
planets. It is, doubtless, to this circumstance that we must
attribute the astonishing success of Kepler in detecting the true
shape of a planetary orbit. Tycho's observations would not have been
sufficiently accurate to have exhibited the elliptic nature of a
planetary orbit which, like that of Venus, differed very little from
a circle.
The more we ponder on this memorable achievement the more striking
will it appear. It must be remembered that in these days we know of
the physical necessity which requires that a planet shall revolve in
an ellipse and not in any other curve. But Kepler had no such
knowledge. Even to the last hour of his life he remained in
ignorance of the existence of any natural cause which ordained that
planets should follow those particular curves which geometers know so
well. Kepler's assignment of the ellipse as the true form of the
planetary orbit is to be regarded as a brilliant guess, the truth of
which Tycho's observations enabled him to verify. Kepler also
succeeded in pointing out the law according to which the velocity of
a planet at different points of its path could be accurately
specified. Here, again, we have to admire the sagacity with which
this marvellously acute astronomer guessed the deep truth of nature.
In this case also he was quite unprovided with any reason for
expecting from physical principles that such a law as he discovered
must be obeyed. It is quite true that Kepler had some slight
knowledge of the existence of what we now know as gravitation. He
had even enunciated the remarkable doctrine that the ebb and flow of
the tide must be attributed to the attraction of the moon on the
waters of the earth. He does not, however, appear to have had any
anticipation of those wonderful discoveries which Newton was destined
to make a little later, in which he demonstrated that the laws
detected by Kepler's marvellous acumen were necessary consequences of
the principle of universal gravitation.
[PLATE: SYMBOLICAL REPRESENTATION OF THE PLANETARY SYSTEM.]
To appreciate the relations of Kepler and Tycho it is necessary to
note the very different way in which these illustrious astronomers
viewed the system of the heavens. It should be observed that
Copernicus had already expounded the true system, which located the
sun at the centre of the planetary system. But in the days of Tycho
Brahe this doctrine had not as yet commanded universal assent. In
fact, the great observer himself did not accept the new views of
Copernicus. It appeared to Tycho that the earth not only appeared to
be the centre of things celestial, but that it actually was the
centre. It is, indeed, not a little remarkable that a student of the
heavens so accurate as Tycho should have deliberately rejected the
Copernican doctrine in favour of the system which now seems so
preposterous. Throughout his great career, Tycho steadily observed
the places of the sun, the moon, and the planets, and as steadily
maintained that all those bodies revolved around the earth fixed in
the centre. Kepler, however, had the advantage of belonging to the
new school. He utilised the observations of Tycho in developing the
great Copernican theory whose teaching Tycho stoutly resisted.
Perhaps a chapter in modern science may illustrate the intellectual
relation of these great men. The revolution produced by Copernicus
in the doctrine of the heavens has often been likened to the
revolution which the Darwinian theory produced in the views held by
biologists as to life on this earth. The Darwinian theory did not at
first command universal assent even among those naturalists whose
lives had been devoted with the greatest success to the study of
organisms. Take, for instance, that great naturalist, Professor
Owen, by whose labours vast extension has been given to our knowledge
of the fossil animals which dwelt on the earth in past ages. Now,
though Owens researches were intimately connected with the great
labours of Darwin, and afforded the latter material for his
epoch-making generalization, yet Owen deliberately refused to accept
the new doctrines. Like Tycho, he kept on rigidly accumulating his
facts under the influence of a set of ideas as to the origin of
living forms which are now universally admitted to be erroneous. If,
therefore, we liken Darwin to Copernicus, and Owen to Tycho, we may
liken the biologists of the present day to Kepler, who interpreted
the results of accurate observation upon sound theoretical
principles.
In reading the works of Kepler in the light of our modern knowledge
we are often struck by the extent to which his perception of the
sublimest truths in nature was associated with the most extravagant
errors and absurdities. But, of course, it must be remembered that
he wrote in an age in which even the rudiments of science, as we now
understand it, were almost entirely unknown.
It may well be doubted whether any joy experienced by mortals is more
genuine than that which rewards the successful searcher after natural
truths. Every science-worker, be his efforts ever so humble, will be
able to sympathise with the enthusiastic delight of Kepler when at
last, after years of toil, the glorious light broke forth, and that
which he considered to be the greatest of his astonishing laws first
dawned upon him. Kepler rightly judged that the number of days which
a planet required to perform its voyage round the sun must be
connected in some manner with the distance from the planet to the
sun; that is to say, with the radius of the planet's orbit, inasmuch
as we may for our present object regard the planet's orbit as
circular.
Here, again, in his search for the unknown law, Kepler had no
accurate dynamical principles to guide his steps. Of course, we now
know not only what the connection between the planet's distance and
the planet's periodic time actually is, but we also know that it is a
necessary consequence of the law of universal gravitation. Kepler,
it is true, was not without certain surmises on the subject, but they
were of the most fanciful description. His notions of the planets,
accurate as they were in certain important respects, were mixed up
with vague ideas as to the properties of metals and the geometrical
relations of the regular solids. Above all, his reasoning was
penetrated by the supposed astrological influences of the stars and
their significant relation to human fate. Under the influence of
such a farrago of notions, Kepler resolved to make all sorts of
trials in his search for the connection between the distance of a
planet from the sun and the time in which the revolution of that
planet was accomplished.
It was quite easily demonstrated that the greater the distance of the
planet from the sun the longer was the time required for its
journey. It might have been thought that the time would be directly
proportional to the distance. It was, however, easy to show that
this supposition did not agree with the fact. Finding that this
simple relation would not do, Kepler undertook a vast series of
calculations to find out the true method of expressing the
connection. At last, after many vain attempts, he found, to his
indescribable joy, that the square of the time in which a planet
revolves around the sun was proportional to the cube of the average
distance of the planet from that body.
The extraordinary way in which Kepler's views on celestial matters
were associated with the wildest speculations, is well illustrated in
the work in which he propounded his splendid discovery just referred
to. The announcement of the law connecting the distances of the
planets from the sun with their periodic times, was then mixed up
with a preposterous conception about the properties of the different
planets. They were supposed to be associated with some profound
music of the spheres inaudible to human ears, and performed only for
the benefit of that being whose soul formed the animating spirit of
the sun.
Kepler was also the first astronomer who ever ventured to predict the
occurrence of that remarkable phenomenon, the transit of a planet in
front of the sun's disc. He published, in 1629, a notice to the
curious in things celestial, in which he announced that both of the
planets, Mercury and Venus, were to make a transit across the sun on
specified days in the winter of 1631. The transit of Mercury was
duly observed by Gassendi, and the transit of Venus also took place,
though, as we now know, the circumstances were such that it was not
possible for the phenomenon to be witnessed by any European
astronomer.
In addition to Kepler's discoveries already mentioned, with which his
name will be for ever associated, his claim on the gratitude of
astronomers chiefly depends on the publication of his famous
Rudolphine tables. In this remarkable work means are provided for
finding the places of the planets with far greater accuracy than had
previously been attainable.
Kepler, it must be always remembered, was not an astronomical
observer. It was his function to deal with the observations made by
Tycho, and, from close study and comparison of the results, to work
out the movements of the heavenly bodies. It was, in fact, Tycho who
provided as it were the raw material, while it was the genius of
Kepler which wrought that material into a beautiful and serviceable
form. For more than a century the Rudolphine tables were regarded as
a standard astronomical work. In these days we are accustomed to
find the movements of the heavenly bodies set forth with all
desirable exactitude in the NAUTICAL ALMANACK, and the similar
publication issued by foreign Governments. Let it be remembered that
it was Kepler who first imparted the proper impulse in this
direction.
[PLATE: THE COMMEMORATION OF THE RUDOLPHINE TABLES.]
When Kepler was twenty-six he married an heiress from Styria, who,
though only twenty-three years old, had already had some experience
in matrimony. Her first husband had died; and it was after her
second husband had divorced her that she received the addresses of
Kepler. It will not be surprising to hear that his domestic affairs
do not appear to have been particularly happy, and his wife died in
1611. Two years later, undeterred by the want of success in his
first venture, he sought a second partner, and he evidently
determined not to make a mistake this time. Indeed, the methodical
manner in which he made his choice of the lady to whom he should
propose has been duly set forth by him and preserved for our
edification. With some self-assurance he asserts that there were no
fewer than eleven spinsters desirous of sharing his joys and
sorrows. He has carefully estimated and recorded the merits and
demerits of each of these would-be brides. The result of his
deliberations was that he awarded himself to an orphan girl,
destitute even of a portion. Success attended his choice, and his
second marriage seems to have proved a much more suitable union than
his first. He had five children by the first wife and seven by the
second.
The years of Kepler's middle life were sorely distracted by a trouble
which, though not uncommon in those days, is one which we find it
difficult to realise at the present time. His mother, Catherine
Kepler, had attained undesirable notoriety by the suspicion that she
was guilty of witchcraft. Years were spent in legal investigations,
and it was only after unceasing exertions on the part of the
astronomer for upwards of a twelvemonth that he was finally able to
procure her acquittal and release from prison.
It is interesting for us to note that at one time there was a
proposal that Kepler should forsake his native country and adopt
England as a home. It arose in this wise. The great man was
distressed throughout the greater part of his life by pecuniary
anxieties. Finding him in a strait of this description, the English
ambassador in Venice, Sir Henry Wotton, in the year 1620, besought
Kepler to come over to England, where he assured him that he would
obtain a favourable reception, and where, he was able to add,
Kepler's great scientific work was already highly esteemed. But his
efforts were unavailing; Kepler would not leave his own country. He
was then forty-nine years of age, and doubtless a home in a foreign
land, where people spoke a strange tongue, had not sufficient
attraction for him, even when accompanied with the substantial
inducements which the ambassador was able to offer. Had Kepler
accepted this invitation, he would, in transferring his home to
England, have anticipated the similar change which took place in the
career of another great astronomer two centuries later. It will be
remembered that Herschel, in his younger days, did transfer himself
to England, and thus gave to England the imperishable fame of
association with his triumphs.
The publication of the Rudolphine tables of the celestial movements
entailed much expense. A considerable part of this was defrayed by
the Government at Venice but the balance occasioned no little trouble
and anxiety to Kepler. No doubt the authorities of those days were
even less Willing to spend money on scientific matters than are the
Governments of more recent times. For several years the imperial
Treasury was importuned to relieve him from his anxieties. The
effects of so much worry, and of the long journeys which were
involved, at last broke down Kepler's health completely. As we have
already mentioned, he had never been strong from infancy, and he
finally succumbed to a fever in November, 1630, at the age of
fifty-nine. He was interred at St. Peter's Church at Ratisbon.
Though Kepler had not those personal characteristics which have made
his great predecessor, Tycho Brahe, such a romantic figure, yet a
picturesque element in Kepler's character is not wanting. It was,
however, of an intellectual kind. His imagination, as well as his
reasoning faculties, always worked together. He was incessantly
prompted by the most extraordinary speculations. The great majority
of them were in a high degree wild and chimerical, but every now and
then one of his fancies struck right to the heart of nature, and an
immortal truth was brought to light.
I remember visiting the observatory of one of our greatest modern
astronomers, and in a large desk he showed me a multitude of
photographs which he had attempted but which had not been successful,
and then he showed me the few and rare pictures which had succeeded,
and by which important truths had been revealed. With a felicity of
expression which I have often since thought of, he alluded to the
contents of the desk as the "chips." They were useless, but they
were necessary incidents in the truly successful work. So it is in
all great and good work. Even the most skilful man of science
pursues many a wrong scent. Time after time he goes off on some
track that plays him false. The greater the man's genius and
intellectual resource, the more numerous will be the ventures which
he makes, and the great majority of those ventures are certain to be
fruitless. They are in fact, the "chips." In Kepler's case the
chips were numerous enough. They were of the most extraordinary
variety and structure. But every now and then a sublime discovery
was made of such a character as to make us regard even the most
fantastic of Kepler's chips with the greatest veneration and respect.
ISAAC NEWTON.
It was just a year after the death of Galileo, that an infant came
into the world who was christened Isaac Newton. Even the great fame
of Galileo himself must be relegated to a second place in comparison
with that of the philosopher who first expounded the true theory of
the universe.
Isaac Newton was born on the 25th of December (old style), 1642, at
Woolsthorpe, in Lincolnshire, about a half-mile from Colsterworth,
and eight miles south of Grantham. His father, Mr. Isaac Newton, had
died a few months after his marriage to Harriet Ayscough, the
daughter of Mr. James Ayscough, of Market Overton, in Rutlandshire.
The little Isaac was at first so excessively frail and weakly that
his life was despaired of. The watchful mother, however, tended her
delicate child with such success that he seems to have thriven better
than might have been expected from the circumstances of his infancy,
and he ultimately acquired a frame strong enough to outlast the
ordinary span of human life.
For three years they continued to live at Woolsthorpe, the widow's
means of livelihood being supplemented by the income from another
small estate at Sewstern, in a neighbouring part of Leicestershire.
[PLATE: WOOLSTHORPE MANOR.
Showing solar dial made by Newton when a boy.]
In 1645, Mrs. Newton took as a second husband the Rev. Barnabas
Smith, and on moving to her new home, about a mile from Woolsthorpe,
she entrusted little Isaac to her mother, Mrs. Ayscough. In due
time we find that the boy was sent to the public school at Grantham,
the name of the master being Stokes. For the purpose of being near
his work, the embryo philosopher was boarded at the house of Mr.
Clark, an apothecary at Grantham. We learn from Newton himself that
at first he had a very low place in the class lists of the school,
and was by no means one of those model school-boys who find favour in
the eyes of the school-master by attention to Latin grammar. Isaac's
first incentive to diligent study seems to have been derived from the
circumstance that he was severely kicked by one of the boys who was
above him in the class. This indignity had the effect of stimulating
young Newton's activity to such an extent that he not only attained
the desired object of passing over the head of the boy who had
maltreated him, but continued to rise until he became the head of the
school.
The play-hours of the great philosopher were devoted to pursuits very
different from those of most school-boys. His chief amusement was
found in making mechanical toys and various ingenious contrivances.
He watched day by day with great interest the workmen engaged in
constructing a windmill in the neighbourhood of the school, the
result of which was that the boy made a working model of the windmill
and of its machinery, which seems to have been much admired, as
indicating his aptitude for mechanics. We are told that Isaac also
indulged in somewhat higher flights of mechanical enterprise. He
constructed a carriage, the wheels of which were to be driven by the
hands of the occupant, while the first philosophical instrument he
made was a clock, which was actuated by water. He also devoted much
attention to the construction of paper kites, and his skill in this
respect was highly appreciated by his schoolfellows. Like a true
philosopher, even at this stage he experimented on the best methods
of attaching the string, and on the proportions which the tail ought
to have. He also made lanthorns of paper to provide himself with
light as he walked to school in the dark winter mornings.
The only love affair in Newton's life appears to have commenced while
he was still of tender years. The incidents are thus described in
Brewster's "Life of Newton," a work to which I am much indebted in
this chapter.
"In the house where he lodged there were some female inmates, in
whose company he appears to have taken much pleasure. One of these,
a Miss Storey, sister to Dr. Storey, a physician at Buckminster, near
Colsterworth, was two or three years younger than Newton and to great
personal attractions she seems to have added more than the usual
allotment of female talent. The society of this young lady and her
companions was always preferred to that of his own school-fellows,
and it was one of his most agreeable occupations to construct for
them little tables and cupboards, and other utensils for holding
their dolls and their trinkets. He had lived nearly six years in the
same house with Miss Storey, and there is reason to believe that
their youthful friendship gradually rose to a higher passion; but the
smallness of her portion, and the inadequacy of his own fortune,
appear to have prevented the consummation of their happiness. Miss
Storey was afterwards twice married, and under the name of Mrs.
Vincent, Dr. Stukeley visited her at Grantham in 1727, at the age of
eighty-two, and obtained from her many particulars respecting the
early history of our author. Newton's esteem for her continued
unabated during his life. He regularly visited her when he went to
Lincolnshire, and never failed to relieve her from little pecuniary
difficulties which seem to have beset her family."
The schoolboy at Grantham was only fourteen years of age when his
mother became a widow for the second time. She then returned to the
old family home at Woolsthorpe, bringing with her the three children
of her second marriage. Her means appear to have been somewhat
scanty, and it was consequently thought necessary to recall Isaac
from the school. His recently-born industry had been such that he
had already made good progress in his studies, and his mother hoped
that he would now lay aside his books, and those silent meditations
to which, even at this early age, he had become addicted. It was
expected that, instead of such pursuits, which were deemed quite
useless, the boy would enter busily into the duties of the farm and
the details of a country life. But before long it became manifest
that the study of nature and the pursuit of knowledge had such a
fascination for the youth that he could give little attention to
aught else. It was plain that he would make but an indifferent
farmer. He greatly preferred experimenting on his water-wheels to
looking after labourers, while he found that working at mathematics
behind a hedge was much more interesting than chaffering about the
price of bullocks in the market place. Fortunately for humanity his
mother, like a wise woman, determined to let her boy's genius have
the scope which it required. He was accordingly sent back to
Grantham school, with the object of being trained in the knowledge
which would fit him for entering the University of Cambridge.
[PLATE: TRINITY COLLEGE, CAMBRIDGE.
Showing Newton's rooms; on the leads of the gateway he placed
his telescope.]
It was the 5th of June, 1660, when Isaac Newton, a youth of eighteen,
was enrolled as an undergraduate of Trinity College, Cambridge.
Little did those who sent him there dream that this boy was destined
to be the most illustrious student who ever entered the portals of
that great seat of learning. Little could the youth himself have
foreseen that the rooms near the gateway which he occupied would
acquire a celebrity from the fact that he dwelt in them, or that the
ante-chapel of his college was in good time to be adorned by that
noble statue, which is regarded as one of the chief art treasures of
Cambridge University, both on account of its intrinsic beauty and the
fact that it commemorates the fame of her most distinguished alumnus,
Isaac Newton, the immortal astronomer. Indeed, his advent at the
University seemed to have been by no means auspicious or brilliant.
His birth was, as we have seen, comparatively obscure, and though he
had already given indication of his capacity for reflecting on
philosophical matters, yet he seems to have been but ill-equipped
with the routine knowledge which youths are generally expected to
take with them to the Universities.
From the outset of his college career, Newton's attention seems to
have been mainly directed to mathematics. Here he began to give
evidence of that marvellous insight into the deep secrets of nature
which more than a century later led so dispassionate a judge as
Laplace to pronounce Newton's immortal work as pre-eminent above all
the productions of the human intellect. But though Newton was one of
the very greatest mathematicians that ever lived, he was never a
mathematician for the mere sake of mathematics. He employed his
mathematics as an instrument for discovering the laws of nature. His
industry and genius soon brought him under the notice of the
University authorities. It is stated in the University records that
he obtained a Scholarship in 1664. Two years later we find that
Newton, as well as many residents in the University, had to leave
Cambridge temporarily on account of the breaking out of the plague.
The philosopher retired for a season to his old home at Woolsthorpe,
and there he remained until he was appointed a Fellow of Trinity
College, Cambridge, in 1667. From this time onwards, Newton's
reputation as a mathematician and as a natural philosopher steadily
advanced, so that in 1669, while still but twenty-seven years of age,
he was appointed to the distinguished position of Lucasian Professor
of Mathematics at Cambridge. Here he found the opportunity to
continue and develop that marvellous career of discovery which formed
his life's work.
The earliest of Newton's great achievements in natural philosophy was
his detection of the composite character of light. That a beam of
ordinary sunlight is, in fact, a mixture of a very great number of
different-coloured lights, is a doctrine now familiar to every one
who has the slightest education in physical science. We must,
however, remember that this discovery was really a tremendous advance
in knowledge at the time when Newton announced it.
[PLATE: DIAGRAM OF A SUNBEAM.]
We here give the little diagram originally drawn by Newton, to
explain the experiment by which he first learned the composition of
light. A sunbeam is admitted into a darkened room through an
opening, H, in a shutter. This beam when not interfered with will
travel in a straight line to the screen, and there reproduce a bright
spot of the same shape as the hole in the shutter. If, however, a
prism of glass, A B C, be introduced so that the beam traverse it,
then it will be seen at once that the light is deflected from its
original track. There is, however, a further and most important
change which takes place. The spot of light is not alone removed to
another part of the screen, but it becomes spread out into a long
band beautifully coloured, and exhibiting the hues of the rainbow. At
the top are the violet rays, and then in descending order we have the
indigo, blue, green, yellow, orange, and red.
The circumstance in this phenomenon which appears to have
particularly arrested Newton's attention, was the elongation which
the luminous spot underwent in consequence of its passage through the
prism. When the prism was absent the spot was nearly circular, but
when the prism was introduced the spot was about five times as long
as it was broad. To ascertain the explanation of this was the first
problem to be solved. It seemed natural to suppose that it might be
due to the thickness of the glass in the prism which the light
traversed, or to the angle of incidence at which the light fell upon
the prism. He found, however, upon careful trial, that the phenomenon
could not be thus accounted for. It was not until after much patient
labour that the true explanation dawned upon him. He discovered that
though the beam of white light looks so pure and so simple, yet in
reality it is composed of differently coloured lights blended
together. These are, of course, indistinguishable in the compound
beam, but they are separated or disentangled, so to speak, by the
action of the prism. The rays at the blue end of the spectrum are
more powerfully deflected by the action of the glass than are the
rays at the red end. Thus, the rays variously coloured red, orange,
yellow, green, blue, indigo, violet, are each conducted to a
different part of the screen. In this way the prism has the effect
of exhibiting the constitution of the composite beam of light.
To us this now seems quite obvious, but Newton did not adopt it
hastily. With characteristic caution he verified the explanation by
many different experiments, all of which confirmed his discovery. One
of these may be mentioned. He made a hole in the screen at that part
on which the violet rays fell. Thus a violet ray was allowed to pass
through, all the rest of the light being intercepted, and on this
beam so isolated he was able to try further experiments. For
instance, when he interposed another prism in its path, he found, as
he expected, that it was again deflected, and he measured the amount
of the deflection. Again he tried the same experiment with one of
the red rays from the opposite end of the coloured band. He allowed
it to pass through the same aperture in the screen, and he tested the
amount by which the second prism was capable of producing deflection.
He thus found, as he had expected to find, that the second prism was
more efficacious in bending the violet rays than in bending the red
rays. Thus he confirmed the fact that the various hues of the
rainbow were each bent by a prism to a different extent, violet being
acted upon the most, and red the least.
[PLATE: ISAAC NEWTON.]
Not only did Newton decompose a white beam into its constituent
colours, but conversely by interposing a second prism with its angle
turned upwards, he reunited the different colours, and thus
reproduced the original beam of white light. In several other ways
also he illustrated his famous proposition, which then seemed so
startling, that white light was the result of a mixture of all hues
of the rainbow. By combining painters' colours in the right
proportion he did not indeed succeed in producing a mixture which
would ordinarily be called white, but he obtained a grey pigment.
Some of this he put on the floor of his room for comparison with a
piece of white paper. He allowed a beam of bright sunlight to fall
upon the paper and the mixed colours side by side, and a friend he
called in for his opinion pronounced that under these circumstances
the mixed colours looked the whiter of the two.
By repeated demonstrations Newton thus established his great
discovery of the composite character of light. He at once perceived
that his researches had an important bearing upon the principles
involved in the construction of a telescope. Those who employed the
telescope for looking at the stars, had been long aware of the
imperfections which prevented all the various rays from being
conducted to the same focus. But this imperfection had hitherto been
erroneously accounted for. It had been supposed that the reason why
success had not been attained in the construction of a refracting
telescope was due to the fact that the object glass, made as it then
was of a single piece, had not been properly shaped. Mathematicians
had abundantly demonstrated that a single lens, if properly figured,
must conduct all rays of light to the same focus, provided all rays
experienced equal refraction in passing through the glass. Until
Newton's discovery of the composition of white light, it had been
taken for granted that the several rays in a white beam were equally
refrangible. No doubt if this had been the case, a perfect telescope
could have been produced by properly shaping the object glass. But
when Newton had demonstrated that light was by no means so simple as
had been supposed, it became obvious that a satisfactory refracting
telescope was an impossibility when only a single object lens was
employed, however carefully that lens might have been wrought. Such
an objective might, no doubt, be made to conduct any one group of
rays of a particular shade to the same focus, but the rays of other
colours in the beam of white light must necessarily travel somewhat
astray. In this way Newton accounted for a great part of the
difficulties which had hitherto beset the attempts to construct a
perfect refracting telescope.
We now know how these difficulties can be, to a great extent,
overcome, by employing for the objective a composite lens made of two
pieces of glass possessing different qualities. To these achromatic
object glasses, as they are called, the great development of
astronomical knowledge, since Newton's time, is due. But it must be
remarked that, although the theoretical possibility of constructing
an achromatic lens was investigated by Newton, he certainly came to
the conclusion that the difficulty could not be removed by employing
a composite objective, with two different kinds of glass. In this
his marvellous sagacity in the interpretation of nature seems for
once to have deserted him. We can, however, hardly regret that
Newton failed to discover the achromatic objective, when we observe
that it was in consequence of his deeming an achromatic objective to
be impossible that he was led to the invention of the reflecting
telescope. Finding, as he believed, that the defects of the
telescope could not be remedied by any application of the principle
of refraction he was led to look in quite a different direction for
the improvement of the tool on which the advancement of astronomy
depended. The REFRACTION of light depended as he had found, upon the
colour of the light. The laws of REFLECTION were, however, quite
independent of the colour. Whether rays be red or green, blue or
yellow, they are all reflected in precisely the same manner from a
mirror. Accordingly, Newton perceived that if he could construct a
telescope the action of which depended upon reflection, instead of
upon refraction, the difficulty which had hitherto proved an
insuperable obstacle to the improvement of the instrument would be
evaded.
[PLATE: SIR ISAAC NEWTON'S LITTLE REFLECTOR.]
For this purpose Newton fashioned a concave mirror from a mixture of
copper and tin, a combination which gives a surface with almost the
lustre of silver. When the light of a star fell upon the surface, an
image of the star was produced in the focus of this mirror, and then
this image was examined by a magnifying eye-piece. Such is the
principle of the famous reflecting telescope which bears the name of
Newton. The little reflector which he constructed, represented in
the adjoining figure, is still preserved as one of the treasures of
the Royal Society. The telescope tube had the very modest dimension
of one inch in diameter. It was, however, the precursor of a whole
series of magnificent instruments, each outstripping the other in
magnitude, until at last the culminating point was attained in 1845,
by the construction of Lord Rosse's mammoth reflector of six feet in
aperture.
Newton's discovery of the composition of light led to an embittered
controversy, which caused no little worry to the great Philosopher.
Some of those who attacked him enjoyed considerable and, it must be
admitted, even well-merited repute in the ranks of science. They
alleged, however, that the elongation of the coloured band which
Newton had noticed was due to this, to that, or to the other--to
anything, in fact, rather than to the true cause which Newton
assigned. With characteristic patience and love of truth, Newton
steadily replied to each such attack. He showed most completely how
utterly his adversaries had misunderstood the subject, and how slight
indeed was their acquaintance with the natural phenomenon in
question. In reply to each point raised, he was ever able to cite
fresh experiments and adduce fresh illustrations, until at last his
opponents retired worsted from the combat.
It has been often a matter for surprise that Newton, throughout his
whole career, should have taken so much trouble to expose the errors
of those who attacked his views. He used even to do this when it
plainly appeared that his adversaries did not understand the subject
they were discussing. A philosopher might have said, "I know I am
right, and whether others think I am right or not may be a matter of
concern to them, but it is certainly not a matter about which I need
trouble. If after having been told the truth they elect to remain in
error, so much the worse for them; my time can be better employed
than in seeking to put such people right." This, however, was not
Newton's method. He spent much valuable time in overthrowing
objections which were often of a very futile description. Indeed, he
suffered a great deal of annoyance from the persistency, and in some
cases one might almost say from the rancour, of the attacks which
were made upon him. Unfortunately for himself, he did not possess
that capacity for sublime indifference to what men may say, which is
often the happy possession of intellects greatly inferior to his.
The subject of optics still continuing to engross Newton's attention,
he followed up his researches into the structure of the sunbeam by
many other valuable investigations in connection with light. Every
one has noticed the beautiful colours manifested in a soap-bubble.
Here was a subject which not unnaturally attracted the attention of
one who had expounded the colours of the spectrum with such success.
He perceived that similar hues were produced by other thin plates of
transparent material besides soap-bubbles, and his ingenuity was
sufficient to devise a method by which the thicknesses of the
different films could be measured. We can hardly, indeed, say that a
like success attended his interpretation of these phenomena to that
which had been so conspicuous in his explanation of the spectrum. It
implies no disparagement to the sublime genius of Newton to admit
that the doctrines he put forth as to the causes of the colours in
the soap-bubbles can be no longer accepted. We must remember that
Newton was a pioneer in accounting for the physical properties of
light. The facts that he established are indeed unquestionable, but
the explanations which he was led to offer of some of them are seen
to be untenable in the fuller light of our present knowledge.
[PLATE: SIR ISAAC NEWTON'S SUN-DIAL.]
Had Newton done nothing beyond making his wonderful discoveries in
light, his fame would have gone down to posterity as one of the
greatest of Nature's interpreters. But it was reserved for him to
accomplish other discoveries, which have pushed even his analysis of
the sunbeam into the background; it is he who has expounded the
system of the universe by the discovery of the law of universal
gravitation.
The age had indeed become ripe for the advent of the genius of
Newton. Kepler had discovered with marvellous penetration the laws
which govern the movements of the planets around the sun, and in
various directions it had been more or less vaguely felt that the
explanation of Kepler's laws, as well as of many other phenomena,
must be sought for in connection with the attractive power of
matter. But the mathematical analysis which alone could deal with
this subject was wanting; it had to be created by Newton.
At Woolsthorpe, in the year 1666, Newton's attention appears to have
been concentrated upon the subject of gravitation. Whatever may be
the extent to which we accept the more or less mythical story as to
how the fall of an apple first directed the attention of the
philosopher to the fact that gravitation must extend through space,
it seems, at all events, certain that this is an excellent
illustration of the line of reasoning which he followed. He argued
in this way. The earth attracts the apple; it would do so, no matter
how high might be the tree from which that apple fell. It would then
seem to follow that this power which resides in the earth by which it
can draw all external bodies towards it, extends far beyond the
altitude of the loftiest tree. Indeed, we seem to find no limit to
it. At the greatest elevation that has ever been attained, the
attractive power of the earth is still exerted, and though we cannot
by any actual experiment reach an altitude more than a few miles
above the earth, yet it is certain that gravitation would extend to
elevations far greater. It is plain, thought Newton, that an apple
let fall from a point a hundred miles above this earth's surface,
would be drawn down by the attraction, and would continually gather
fresh velocity until it reached the ground. From a hundred miles it
was natural to think of what would happen at a thousand miles, or at
hundreds of thousands of miles. No doubt the intensity of the
attraction becomes weaker with every increase in the altitude, but
that action would still exist to some extent, however lofty might be
the elevation which had been attained.
It then occurred to Newton, that though the moon is at a distance of
two hundred and forty thousand miles from the earth, yet the
attractive power of the earth must extend to the moon. He was
particularly led to think of the moon in this connection, not only
because the moon is so much closer to the earth than are any other
celestial bodies, but also because the moon is an appendage to the
earth, always revolving around it. The moon is certainly attracted
to the earth, and yet the moon does not fall down; how is this to be
accounted for? The explanation was to be found in the character of
the moon's present motion. If the moon were left for a moment at
rest, there can be no doubt that the attraction of the earth would
begin to draw the lunar globe in towards our globe. In the course of
a few days our satellite would come down on the earth with a most
fearful crash. This catastrophe is averted by the circumstance that
the moon has a movement of revolution around the earth. Newton was
able to calculate from the known laws of mechanics, which he had
himself been mainly instrumental in discovering, what the attractive
power of the earth must be, so that the moon shall move precisely as
we find it to move. It then appeared that the very power which makes
an apple fall at the earth's surface is the power which guides the
moon in its orbit.
[PLATE: SIR ISAAC NEWTON'S TELESCOPE.]
Once this step had been taken, the whole scheme of the universe might
almost be said to have become unrolled before the eye of the
philosopher. It was natural to suppose that just as the moon was
guided and controlled by the attraction of the earth, so the earth
itself, in the course of its great annual progress, should be guided
and controlled by the supreme attractive power of the sun. If this
were so with regard to the earth, then it would be impossible to
doubt that in the same way the movements of the planets could be
explained to be consequences of solar attraction.
It was at this point that the great laws of Kepler became especially
significant. Kepler had shown how each of the planets revolves in an
ellipse around the sun, which is situated on one of the foci. This
discovery had been arrived at from the interpretation of
observations. Kepler had himself assigned no reason why the orbit of
a planet should be an ellipse rather than any other of the infinite
number of closed curves which might be traced around the sun. Kepler
had also shown, and here again he was merely deducing the results
from observation, that when the movements of two planets were
compared together, the squares of the periodic times in which each
planet revolved were proportional to the cubes of their mean
distances from the sun. This also Kepler merely knew to be true as a
fact, he gave no demonstration of the reason why nature should have
adopted this particular relation between the distance and the
periodic time rather than any other. Then, too, there was the law by
which Kepler with unparalleled ingenuity, explained the way in which
the velocity of a planet varies at the different points of its track,
when he showed how the line drawn from the sun to the planet
described equal areas around the sun in equal times. These were the
materials with which Newton set to work. He proposed to infer from
these the actual laws regulating the force by which the sun guides
the planets. Here it was that his sublime mathematical genius came
into play. Step by step Newton advanced until he had completely
accounted for all the phenomena.
In the first place, he showed that as the planet describes equal
areas in equal times about the sun, the attractive force which the
sun exerts upon it must necessarily be directed in a straight line
towards the sun itself. He also demonstrated the converse truth,
that whatever be the nature of the force which emanated from a sun,
yet so long as that force was directed through the sun's centre, any
body which revolved around it must describe equal areas in equal
times, and this it must do, whatever be the actual character of the
law according to which the intensity of the force varies at different
parts of the planet's journey. Thus the first advance was taken in
the exposition of the scheme of the universe.
The next step was to determine the law according to which the force
thus proved to reside in the sun varied with the distance of the
planet. Newton presently showed by a most superb effort of
mathematical reasoning, that if the orbit of a planet were an ellipse
and if the sun were at one of the foci of that ellipse, the intensity
of the attractive force must vary inversely as the square of the
planet's distance. If the law had any other expression than the
inverse square of the distance, then the orbit which the planet must
follow would not be an ellipse; or if an ellipse, it would, at all
events, not have the sun in the focus. Hence he was able to show
from Kepler's laws alone that the force which guided the planets was
an attractive power emanating from the sun, and that the intensity of
this attractive power varied with the inverse square of the distance
between the two bodies.
These circumstances being known, it was then easy to show that the
last of Kepler's three laws must necessarily follow. If a number of
planets were revolving around the sun, then supposing the materials
of all these bodies were equally affected by gravitation, it can be
demonstrated that the square of the periodic time in which each
planet completes its orbit is proportional to the cube of the
greatest diameter in that orbit.
[PLATE: SIR ISAAC NEWTON'S ASTROLABE.]
These superb discoveries were, however, but the starting point from
which Newton entered on a series of researches, which disclosed many
of the profoundest secrets in the scheme of celestial mechanics. His
natural insight showed that not only large masses like the sun and
the earth, and the moon, attract each other, but that every particle
in the universe must attract every other particle with a force which
varies inversely as the square of the distance between them. If, for
example, the two particles were placed twice as far apart, then the
intensity of the force which sought to bring them together would be
reduced to one-fourth. If two particles, originally ten miles
asunder, attracted each other with a certain force, then, when the
distance was reduced to one mile, the intensity of the attraction
between the two particles would be increased one-hundred-fold. This
fertile principle extends throughout the whole of nature. In some
cases, however, the calculation of its effect upon the actual
problems of nature would be hardly possible, were it not for another
discovery which Newton's genius enabled him to accomplish. In the
case of two globes like the earth and the moon, we must remember that
we are dealing not with particles, but with two mighty masses of
matter, each composed of innumerable myriads of particles. Every
particle in the earth does attract every particle in the moon with a
force which varies inversely as the square of their distance. The
calculation of such attractions is rendered feasible by the following
principle. Assuming that the earth consists of materials
symmetrically arranged in shells of varying densities, we may then,
in calculating its attraction, regard the whole mass of the globe as
concentrated at its centre. Similarly we may regard the moon as
concentrated at the centre of its mass. In this way the earth and
the moon can both be regarded as particles in point of size, each
particle having, however, the entire mass of the corresponding
globe. The attraction of one particle for another is a much more
simple matter to investigate than the attraction of the myriad
different points of the earth upon the myriad different points of the
moon.
Many great discoveries now crowded in upon Newton. He first of all
gave the explanation of the tides that ebb and flow around our
shores. Even in the earliest times the tides had been shown to be
related to the moon. It was noticed that the tides were specially
high during full moon or during new moon, and this circumstance
obviously pointed to the existence of some connection between the
moon and these movements of the water, though as to what that
connection was no one had any accurate conception until Newton
announced the law of gravitation. Newton then made it plain that the
rise and fall of the water was simply a consequence of the attractive
power which the moon exerted upon the oceans lying upon our globe. He
showed also that to a certain extent the sun produces tides, and he
was able to explain how it was that when the sun and the moon both
conspire, the joint result was to produce especially high tides,
which we call "spring tides"; whereas if the solar tide was low,
while the lunar tide was high, then we had the phenomenon of "neap"
tides.
But perhaps the most signal of Newton's applications of the law of
gravitation was connected with certain irregularities in the
movements of the moon. In its orbit round the earth our satellite
is, of course, mainly guided by the great attraction of our globe. If
there were no other body in the universe, then the centre of the moon
must necessarily perform an ellipse, and the centre of the earth
would lie in the focus of that ellipse. Nature, however, does not
allow the movements to possess the simplicity which this arrangement
would imply, for the sun is present as a source of disturbance. The
sun attracts the moon, and the sun attracts the earth, but in
different degrees, and the consequence is that the moon's movement
with regard to the earth is seriously affected by the influence of
the sun. It is not allowed to move exactly in an ellipse, nor is the
earth exactly in the focus. How great was Newton's achievement in
the solution of this problem will be appreciated if we realise that
he not only had to determine from the law of gravitation the nature
of the disturbance of the moon, but he had actually to construct the
mathematical tools by which alone such calculations could be
effected.
The resources of Newton's genius seemed, however, to prove equal to
almost any demand that could be made upon it. He saw that each
planet must disturb the other, and in that way he was able to render
a satisfactory account of certain phenomena which had perplexed all
preceding investigators. That mysterious movement by which the pole
of the earth sways about among the stars had been long an unsolved
enigma, but Newton showed that the moon grasped with its attraction
the protuberant mass at the equatorial regions of the earth, and thus
tilted the earth's axis in a way that accounted for the phenomenon
which had been known but had never been explained for two thousand
years. All these discoveries were brought together in that immortal
work, Newton's "Principia."
Down to the year 1687, when the "Principia" was published, Newton had
lived the life of a recluse at Cambridge, being entirely occupied
with those transcendent researches to which we have referred. But in
that year he issued from his seclusion under circumstances of
considerable historical interest. King James the Second attempted an
invasion of the rights and privileges of the University of Cambridge
by issuing a command that Father Francis, a Benedictine monk, should
be received as a Master of Arts in the University, without having taken
the oaths of allegiance and supremacy. With this arbitrary command
the University sternly refused to comply. The Vice-Chancellor was
accordingly summoned to answer for an act of contempt to the authority
of the Crown. Newton was one of nine delegates who were chosen to
defend the independence of the University before the High Court.
They were able to show that Charles the Second, who had issued a
MANDAMUS under somewhat similar circumstances, had been induced after
due consideration to withdraw it. This argument appeared satisfactory,
and the University gained their case. Newton's next step in public
life was his election, by a narrow majority, as member for the
University, and during the years 1688 and 1689, he seems to have
attended to his parliamentary duties with considerable regularity.
An incident which happened in 1692 was apparently the cause of
considerable disturbance in Newton's equanimity, if not in his
health. He had gone to early morning chapel, leaving a lighted
candle among his papers on his desk. Tradition asserts that his
little dog "Diamond" upset the candle; at all events, when Newton
came back he found that many valuable papers had perished in a
conflagration. The loss of these manuscripts seems to have had a
serious effect. Indeed, it has been asserted that the distress
reduced Newton to a state of mental aberration for a considerable
time. This has, apparently, not been confirmed, but there is no
doubt that he experienced considerable disquiet, for in writing on
September 13th, 1693, to Mr. Pepys, he says:
"I am extremely troubled at the embroilment I am in, and have
neither ate nor slept well this twelvemonth, nor have my former
consistency of mind."
Notwithstanding the fame which Newton had achieved, by the
publication of his, "Principia," and by all his researches, the State
had not as yet taken any notice whatever of the most illustrious man
of science that this or any other country has ever produced. Many of
his friends had exerted themselves to procure him some permanent
appointment, but without success. It happened, however, that Mr.
Montagu, who had sat with Newton in Parliament, was appointed
Chancellor of the Exchequer in 1694. Ambitious of distinction in his
new office, Mr. Montagu addressed himself to the improvement of the
current coin, which was then in a very debased condition. It
fortunately happened that an opportunity occurred of appointing a new
official in the Mint; and Mr. Montagu on the 19th of March, 1695,
wrote to offer Mr. Newton the position of warden. The salary was to
be five or six hundred a year, and the business would not require
more attendance than Newton could spare. The Lucasian professor
accepted this post, and forthwith entered upon his new duties.
The knowledge of physics which Newton had acquired by his experiments
was of much use in connection with his duties at the Mint. He
carried out the re-coinage with great skill in the course of two
years, and as a reward for his exertions, he was appointed, in 1697,
to the Mastership of the Mint, with a salary between 1,200 Pounds and
1,500 Pounds per annum. In 1701, his duties at the Mint being so
engrossing, he resigned his Lucasian professorship at Cambridge, and
at the same time he had to surrender his fellowship at Trinity
College. This closed his connection with the University of
Cambridge. It should, however, be remarked that at a somewhat
earlier stage in his career he was very nearly being appointed to an
office which might have enabled the University to retain the great
philosopher within its precincts. Some of his friends had almost
succeeded in securing his nomination to the Provostship of King's
College, Cambridge; the appointment, however, fell through, inasmuch
as the statute could not be evaded, which required that the Provost
of King's College should be in holy orders.
In those days it was often the custom for illustrious mathematicians,
when they had discovered a solution for some new and striking
problem, to publish that problem as a challenge to the world, while
withholding their own solution. A famous instance of this is found
in what is known as the Brachistochrone problem, which was solved by
John Bernouilli. The nature of this problem may be mentioned. It
was to find the shape of the curve along which a body would slide
down from one point (A) to another point (B) in the shortest time. It
might at first be thought that the straight line from A to B, as it
is undoubtedly the shortest distance between the points, would also
be the path of quickest descent; but this is not so. There is a
curved line, down which a bead, let us say, would run on a smooth
wire from A to B in a shorter time than the same bead would require
to run down the straight wire. Bernouilli's problem was to find out
what that curve must be. Newton solved it correctly; he showed that
the curve was a part of what is termed a cycloid--that is to say, a
curve like that which is described by a point on the rim of a
carriage-wheel as the wheel runs along the ground. Such was Newton's
geometrical insight that he was able to transmit a solution of the
problem on the day after he had received it, to the President of the
Royal Society.
In 1703 Newton, whose world wide fame was now established, was
elected President of the Royal Society. Year after year he was
re-elected to this distinguished position, and his tenure, which
lasted twenty-five years, only terminated with his life. It was in
discharge of his duties as President of the Royal Society that Newton
was brought into contact with Prince George of Denmark. In April,
1705, the Queen paid a visit to Cambridge as the guest of Dr.
Bentley, the then Master of Trinity, and in a court held at Trinity
Lodge on April 15th, 1705, the honour of knighthood was conferred
upon the discoverer of gravitation.
Urged by illustrious friends, who sought the promotion of knowledge,
Newton gave his attention to the publication of a new edition of the
"Principia." His duties at the Mint, however, added to the supreme
duty of carrying on his original investigations, left him but little
time for the more ordinary task of the revision. He was accordingly
induced to associate with himself for this purpose a distinguished
young mathematician, Roger Coates, a Fellow of Trinity College,
Cambridge, who had recently been appointed Plumian Professor of
Astronomy. On July 27th, 1713, Newton, by this time a favourite at
Court, waited on the Queen, and presented her with a copy of the new
edition of the "Principia."
Throughout his life Newton appears to have been greatly interested in
theological studies, and he specially devoted his attention to the
subject of prophecy. He left behind him a manuscript on the
prophecies of Daniel and the Apocalypse of St. John, and he also
wrote various theological papers. Many other subjects had from time
to time engaged his attention. He studied the laws of heat; he
experimented in pursuit of the dreams of the Alchymist; while the
philosopher who had revealed the mechanism of the heavens found
occasional relaxation in trying to interpret hieroglyphics. In the
last few years of his life he bore with fortitude a painful ailment,
and on Monday, March 20th, 1727, he died in the eighty-fifth year of
his age. On Tuesday, March 28th, he was buried in Westminster Abbey.
Though Newton lived long enough to receive the honour that his
astonishing discoveries so justly merited, and though for many years
of his life his renown was much greater than that of any of his
contemporaries, yet it is not too much to say that, in the years
which have since elapsed, Newton's fame has been ever steadily
advancing, so that it never stood higher than it does at this moment.
We hardly know whether to admire more the sublime discoveries at
which he arrived, or the extraordinary character of the intellectual
processes by which those discoveries were reached. Viewed from
either standpoint, Newton's "Principia" is incomparably the greatest
work on science that has ever yet been produced.
[PLATE: SIR ISAAC NEWTON'S SUN-DIAL IN THE ROYAL SOCIETY.]
FLAMSTEED.
Among the manuscripts preserved at Greenwich Observatory are certain
documents in which Flamsteed gives an account of his own life. We
may commence our sketch by quoting the following passage from this
autobiography:--"To keep myself from idleness, and to recreate
myself, I have intended here to give some account of my life, in my
youth, before the actions thereof, and the providences of God
therein, be too far passed out of my memory; and to observe the
accidents of all my years, and inclinations of my mind, that
whosoever may light upon these papers may see I was not so wholly
taken up, either with my father's business or my mathematics, but
that I both admitted and found time for other as weighty
considerations."
The chief interest which attaches to the name of Flamsteed arises
from the fact that he was the first of the illustrious series of
Astronomers Royal who have presided over Greenwich Observatory. In
that capacity Flamsteed was able to render material assistance to
Newton by providing him with the observations which his lunar theory
required.
John Flamsteed was born at Denby, in Derbyshire, on the 19th of
August, 1646. His mother died when he was three years old, and the
second wife, whom his father took three years later, only lived until
Flamsteed was eight, there being also two younger sisters. In his
boyhood the future astronomer tells us that he was very fond of those
romances which affect boy's imagination, but as he writes, "At twelve
years of age I left all the wild ones and betook myself to read the
better sort of them, which, though they were not probable, yet
carried no seeming impossibility in the picturing." By the time
Flamsteed was fifteen years old he had embarked in still more serious
work, for he had read Plutarch's "Lives," Tacitus' "Roman History,"
and many other books of a similar description. In 1661 he became ill
with some serious rheumatic affection, which obliged him to be
withdrawn from school. It was then for the first time that he
received the rudiments of a scientific education. He had, however,
attained his sixteenth year before he made any progress in
arithmetic. He tells us how his father taught him "the doctrine of
fractions," and "the golden rule of three"--lessons which he seemed
to have learned easily and quickly. One of the books which he read
at this time directed his attention to astronomical instruments, and
he was thus led to construct for himself a quadrant, by which he
could take some simple astronomical observations. He further
calculated a table to give the sun's altitudes at different hours,
and thus displayed those tastes for practical astronomy which he
lived to develop so greatly. It appears that these scientific
studies were discountenanced by his father, who designed that his son
should follow a business career. Flamsteed's natural inclination,
however, forced him to prosecute astronomical work, notwithstanding
the impediments that lay in his path. Unfortunately, his
constitutional delicacy seems to have increased, and he had just
completed his eighteenth year, "when," to use his own words, "the
winter came on and thrust me again into the chimney, whence the heat
and the dryness of the preceding summer had happily once before
withdrawn me. But, it not being a fit season for physic, it was
thought fit to let me alone this winter, and try the skill of another
physician on me in the spring."
It appears that at this time a quack named Valentine Greatrackes, was
reputed to have effected most astonishing cures in Ireland merely by
the stroke of his hands, without the application of any medicine
whatever. Flamsteed's father, despairing of any remedy for his son
from the legitimate branch of the profession, despatched him to
Ireland on August 26th, 1665, he being then, as recorded with
astronomical accuracy, "nineteen years, six days, and eleven hours
old." The young astronomer, accompanied by a friend, arrived on a
Tuesday at Liverpool but the wind not being favourable, they remained
there till the following Friday, when a shift of the wind to the east
took place. They embarked accordingly on a vessel called the SUPPLY
at noon, and on Saturday night came in sight of Dublin. Ere they
could land, however, they were nearly being wrecked on Lambay
Island. This peril safely passed, there was a long delay for
quarantine before they were at last allowed on shore. On Thursday,
September 6th, they set out from Dublin, where they had been
sojourning at the "Ship" Hotel, in Dame Street, towards Assaune,
where Greatrackes received his patients.
[PLATE: FLAMSTEED'S HOUSE.]
Flamsteed gives an interesting account of his travels in Ireland.
They dined at Naas on the first day, and on September 8th they
reached Carlow, a town which is described as one of the fairest they
saw on their journey. By Sunday morning, September 10th, having lost
their way several times, they reached Castleton, called commonly Four
Mile Waters. Flamsteed inquired of the host in the inn where they
might find a church, but was told that the minister lived twelve
miles away, and that they had no sermon except when he came to
receive his tithes once a year, and a woman added that "they had
plenty enough of everything necessary except the word of God." The
travellers accordingly went on to Cappoquin, which lies up the river
Blackwater, on the road to Lismore, eight miles from Youghal. Thence
they immediately started on foot to Assaune. About a mile from
Cappoquin, and entering into the house of Mr. Greatrackes, they saw
him touch several patients, "whereof some were nearly cured, others
were on the mending hand, and some on whom his strokes had no
effect." Flamsteed was touched by the famous quack on the afternoon
of September 11th, but we are hardly surprised to hear his remark
that "he found not his disease to stir." Next morning the astronomer
came again to see Mr. Greatrackes, who had "a kind of majestical yet
affable presence, and a composed carriage." Even after the third
touching had been submitted to, no benefit seems to have been
derived. We must, however record, to the credit of Mr. Greatrackes,
that he refused to accept any payment from Flamsteed, because he was
a stranger.
Finding it useless to protract his stay any longer, Flamsteed and his
friend set out on their return to Dublin. In the course of his
journey he seems to have been much impressed with Clonmel, which he
describes as an "exceedingly pleasantly seated town." But in those
days a journey to Ireland was so serious an enterprise that when
Flamsteed did arrive safely back at Derby after an absence of a
month, he adds, "For God's providence in this journey, His name be
praised, Amen."
As to the expected benefits to his health from the expedition we may
quote his own words: "In the winter following I was indifferent
hearty, and my disease was not so violent as it used to be at that
time formerly. But whether through God's mercy I received this
through Mr. Greatrackes' touch, or my journey and vomiting at sea, I
am uncertain; but, by some circumstances, I guess that I received a
benefit from both."
It is evident that by this time Flamsteed's interest in all
astronomical matters had greatly increased. He studied the
construction of sun-dials, he formed a catalogue of seventy of the
fixed stars, with their places on the heavens, and he computed the
circumstances of the solar eclipse which was to happen on June 22nd,
1666. It is interesting to note that even in those days the
doctrines of the astrologers still found a considerable degree of
credence, and Flamsteed spent a good deal of his time in astrological
studies and computations. He investigated the methods of casting a
nativity, but a suspicion, or, indeed, rather more than a suspicion,
seems to have crossed his mind as to the value of these astrological
predictions, for he says in fine, "I found astrology to give
generally strong conjectural hints, not perfect declarations."
All this time, however, the future Astronomer Royal was steadily
advancing in astronomical inquiries of a recondite nature. He had
investigated the obliquity of the ecliptic with extreme care, so far
as the circumstances of astronomical observation would at that time
permit. He had also sought to discover the sun's distance from the
earth in so far as it could be obtained by determining when the moon
was exactly half illuminated, and he had measured, with much
accuracy, the length of the tropical year. It will thus be seen
that, even at the age of twenty, Flamsteed had made marked progress,
considering how much his time had been interfered with by ill-health.
Other branches of astronomy began also to claim his attention. We
learn that in 1669 and 1670 he compared the planets Jupiter and Mars
with certain fixed stars near which they passed. His instrumental
means, though very imperfect, were still sufficient to enable him to
measure the intervals on the celestial sphere between the planets and
the stars. As the places of the stars were known, Flamsteed was thus
able to obtain the places of the planets. This is substantially the
way in which astronomers of the present day still proceed when they
desire to determine the places of the planets, inasmuch as, directly
or indirectly those places are always obtained relatively to the
fixed stars. By his observations at this early period, Flamsteed
was, it is true, not able to obtain any great degree of accuracy; he
succeeded, however, in proving that the tables by which the places of
the planets were ordinarily given were not to be relied upon.
[PLATE: FLAMSTEED.]
Flamsteed's labours in astronomy and in the allied branches of
science were now becoming generally known, and he gradually came to
correspond with many distinguished men of learning. One of the first
occasions which brought the talents of the young astronomer into fame
was the publication of some calculations concerning certain
astronomical phenomena which were to happen in the year 1670. In the
monthly revolution of the moon its disc passes over those stars which
lie along its track. The disappearance of a star by the
interposition of the moon is called an "occultation." Owing to the
fact that our satellite is comparatively near us, the position which
the moon appears to occupy on the heavens varies from different parts
of the earth, it consequently happens that a star which would be
occulted to an observer in one locality, would often not be occulted
to an observer who was situated elsewhere. Even when an occultation
is visible from both places, the times at which the star disappears
from view will, generally speaking, be different. Much calculation
is therefore necessary to decide the circumstances under which the
occultations of stars may be visible from any particular station.
Having a taste for such computations, Flamsteed calculated the
occultations which were to happen in the year 1670, it being the case
that several remarkable stars would be passed over by the moon during
this year. Of course at the present time, we find such information
duly set forth in the NAUTICAL ALMANAC, but a couple of centuries ago
there was no such source of astronomical knowledge as is now to be
found in that invaluable publication, which astronomers and
navigators know so well. Flamsteed accordingly sent the results of
his work to the President of the Royal Society. The paper which
contained them was received very favourably, and at once brought
Flamsteed into notice among the most eminent members of that
illustrious body, one of whom, Mr. Collins, became through life his
faithful friend and constant correspondent. Flamsteed's father was
naturally gratified with the remarkable notice which his son was
receiving from the great and learned; accordingly he desired him to
go to London, that he might make the personal acquaintance of those
scientific friends whom he had only known by correspondence
previously. Flamsteed was indeed glad to avail himself of this
opportunity. Thus he became acquainted with Dr. Barrow, and
especially with Newton, who was then Lucasian Professor of
Mathematics at Cambridge. It seems to have been in consequence of
this visit to London that Flamsteed entered himself as a member of
Jesus College, Cambridge. We have but little information as to his
University career, but at all events he took his degree of M.A. on
June 5th, 1674.
Up to this time it would seem that Flamsteed had been engaged, to a
certain extent, in the business carried on by his father. It is true
that he does not give any explicit details, yet there are frequent
references to journeys which he had to take on business matters. But
the time now approached when Flamsteed was to start on an independent
career, and it appears that he took his degree in Cambridge with the
object of entering into holy orders, so that he might settle in a
small living near Derby, which was in the gift of a friend of his
father, and would be at the disposal of the young astronomer. This
scheme was, however, not carried out, but Flamsteed does not tell us
why it failed, his only remark being, that "the good providence of
God that had designed me for another station ordered it otherwise."
Sir Jonas Moore, one of the influential friends whom Flamsteed's
talents had attracted, seems to have procured for him the position of
king's astronomer, with a salary of 100 pounds per annum. A larger
salary appears to have been designed at first for this office, which
was now being newly created, but as Flamsteed was resolved on taking
holy orders, a lesser salary was in his case deemed sufficient. The
building of the observatory, in which the first Astronomer Royal was
to be installed, seems to have been brought about, or, at all events,
its progress was accelerated, in a somewhat curious manner.
A Frenchman, named Le Sieur de S. Pierre, came over to London to
promulgate a scheme for discovering longitudes, then a question of
much importance. He brought with him introductions to distinguished
people, and his mission attracted a great deal of attention. The
proposals which he made came under Flamsteed's notice, who pointed
out that the Frenchman's projects were quite inapplicable in the
present state of astronomical science, inasmuch as the places of the
stars were not known with the degree of accuracy which would be
necessary if such methods were to be rendered available. Flamsteed
then goes on to say:--"I heard no more of the Frenchman after this;
but was told that my letters had been shown King Charles. He was
startled at the assertion of the fixed stars' places being false in
the catalogue, and said, with some vehemence, he must have them anew
observed, examined, and corrected, for the use of his seamen."
The first question to be settled was the site for the new
observatory. Hyde Park and Chelsea College were both mentioned as
suitable localities, but, at Sir Christopher Wren's suggestion,
Greenwich Hill was finally resolved upon. The king made a grant of
five hundred pounds of money. He gave bricks from Tilbury Fort,
while materials, in the shape of wood, iron, and lead, were available
from a gatehouse demolished in the Tower. The king also promised
whatever further material aid might be shown to be necessary. The
first stone of the Royal Observatory was laid on August 10th, 1675,
and within a few years a building was erected in which the art of
modern practical astronomy was to be created. Flamsteed strove with
extraordinary diligence, and in spite of many difficulties, to obtain
a due provision of astronomical instruments, and to arrange for the
carrying on of his observations. Notwithstanding the king's
promises, the astronomer was, however, but scantily provided with
means, and he had no assistants to help him in his work. It follows
that all the observations, as well as the reductions, and, indeed,
all the incidental work of the observatory, had to be carried on by
himself alone. Flamsteed, as we have seen, had, however, many
staunch friends. Sir Jonas Moore in particular at all times rendered
him most valuable assistance, and encouraged him by the warm sympathy
and keen interest which he showed in astronomy. The work of the
first Astronomer Royal was frequently interrupted by recurrent
attacks of the complaints to which we have already referred. He says
himself that "his distempers stick so close that that he cannot
remove them," and he lost much time by prostration from headaches, as
well as from more serious affections.
The year 1678 found him in the full tide of work in his observatory.
He was specially engaged on the problem of the earth's motion, which
he sought to derive from observations of the sun and of Venus. But
this, as well as many other astronomical researches which he
undertook, were only subsidiary to that which he made the main task
of his life, namely, the formation of a catalogue of fixed stars. At
the time when Flamsteed commenced his career, the only available
catalogue of fixed stars was that of Tycho Brahe. This work had been
published at the commencement of the seventeenth century, and it
contained about a thousand stars. The positions assigned to these
stars, though obtained with wonderful skill, considering the many
difficulties under which Tycho laboured, were quite inaccurate when
judged by our modern standards. Tycho's instruments were necessarily
most rudely divided, and he had, of course, no telescopes to aid him.
Consequently it was merely by a process of sighting that he could
obtain the places of the stars. It must further be remembered that
Tycho had no clocks, and no micrometers. He had, indeed, but little
correct knowledge of the motions of the heavenly bodies to guide
him. To determine the longitudes of a few principal stars he
conceived the ingenious idea of measuring by day the position of
Venus with respect to the sun, an observation which the exceptional
brightness of this planet rendered possible without telescopic aid,
and then by night he observed the position of Venus with regard to
the stars.
It has been well remarked by Mr. Baily, in his introduction to the
"British Catalogue of Stars," that "Flamsteed's observations, by a
fortunate combination of circumstances, commenced a new and a
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