Charter; among the original members being Boyle, Hooke, Christopher
Wren, and other less famous names. Boyle was a great experimenter, a
worthy follower of Dr. Gilbert. Hooke began as his assistant, but being
of a most extraordinary ingenuity he rapidly rose so as to exceed his
master in importance. Fate has been a little unkind to Hooke in placing
him so near to Newton; had he lived in an ordinary age he would
undoubtedly have shone as a star of the first magnitude. With great
ingenuity, remarkable scientific insight, and consummate experimental
skill, he stands in many respects almost on a level with Galileo. But it
is difficult to see stars even of the first magnitude when the sun is
up, and thus it happens that the name and fame of this brilliant man are
almost lost in the blaze of Newton. Of Christopher Wren I need not say
much. He is well known as an architect, but he was a most accomplished
all-round man, and had a considerable taste and faculty for science.
These then were the luminaries of the Royal Society at the time we are
speaking of, and to them Newton's first scientific publication was
submitted. He communicated to them an account of his reflecting
telescope, and presented them with the instrument.
Their reception of it surprised him; they were greatly delighted with
it, and wrote specially thanking him for the communication, and assuring
him that all right should be done him in the matter of the invention.
The Bishop of Salisbury (Bishop Burnet) proposed him for election as a
fellow, and elected he was.
In reply, he expressed his surprise at the value they set on the
telescope, and offered, if they cared for it, to send them an account of
a discovery which he doubts not will prove much more grateful than the
communication of that instrument, "being in my judgment the oddest, if
not the most considerable detection that has recently been made into the
operations of Nature."
So he tells them about his optical researches and his discovery of the
nature of white light, writing them a series of papers which were long
afterwards incorporated and published as his _Optics_. A magnificent
work, which of itself suffices to place its author in the first rank of
the world's men of science.
The nature of white light, the true doctrine of colour, and the
differential calculus! besides a good number of minor results--binomial
theorem, reflecting telescope, sextant, and the like; one would think it
enough for one man's life-work, but the masterpiece remains still to be
mentioned. It is as when one is considering Shakspeare: _King Lear_,
_Macbeth_, _Othello_,--surely a sufficient achievement,--but the
masterpiece remains.
Comparisons in different departments are but little help perhaps,
nevertheless it seems to me that in his own department, and considered
simply as a man of science, Newton towers head and shoulders over, not
only his contemporaries--that is a small matter--but over every other
scientific man who has ever lived, in a way that we can find no parallel
for in other departments. Other nations admit his scientific
pre-eminence with as much alacrity as we do.
Well, we have arrived at the year 1672 and his election to the Royal
Society. During the first year of his membership there was read at one
of the meetings a paper giving an account of a very careful
determination of the length of a degree (_i.e._ of the size of the
earth), which had been made by Picard near Paris. The length of the
degree turned out to be not sixty miles, but nearly seventy miles. How
soon Newton heard of this we do not learn--probably not for some
years,--Cambridge was not so near London then as it is now, but
ultimately it was brought to his notice. Armed with this new datum, his
old speculation concerning gravity occurred to him. He had worked out
the mechanics of the solar system on a certain hypothesis, but it had
remained a hypothesis somewhat out of harmony with apparent fact. What
if it should turn out to be true after all!
He took out his old papers and began again the calculation. If gravity
were the force keeping the moon in its orbit, it would fall toward the
earth sixteen feet every minute. How far did it fall? The newly known
size of the earth would modify the figures: with intense excitement he
runs through the working, his mind leaps before his hand, and as he
perceives the answer to be coming out right, all the infinite meaning
and scope of his mighty discovery flashes upon him, and he can no longer
see the paper. He throws down the pen; and the secret of the universe
is, to one man, known.
But of course it had to be worked out. The meaning might flash upon him,
but its full detail required years of elaboration; and deeper and deeper
consequences revealed themselves to him as he proceeded.
For two years he devoted himself solely to this one object. During
those years he lived but to calculate and think, and the most ludicrous
stories are told concerning his entire absorption and inattention to
ordinary affairs of life. Thus, for instance, when getting up in a
morning he would sit on the side of the bed half-dressed, and remain
like that till dinner time. Often he would stay at home for days
together, eating what was taken to him, but without apparently noticing
what he was doing.
One day an intimate friend, Dr. Stukely, called on him and found on the
table a cover laid for his solitary dinner. After waiting a long time,
Dr. Stukely removed the cover and ate the chicken underneath it,
replacing and covering up the bones again. At length Newton appeared,
and after greeting his friend, sat down to dinner, but on lifting the
cover he said in surprise, "Dear me, I thought I had not dined, but I
see I have."
It was by this continuous application that the _Principia_ was
accomplished. Probably nothing of the first magnitude can be
accomplished without something of the same absorbed unconsciousness and
freedom from interruption. But though desirable and essential for the
_work_, it was a severe tax upon the powers of the _man_. There is, in
fact, no doubt that Newton's brain suffered temporary aberration after
this effort for a short time. The attack was slight, and it has been
denied; but there are letters extant which are inexplicable otherwise,
and moreover after a year or two he writes to his friends apologizing
for strange and disjointed epistles, which he believed he had written
without understanding clearly what he wrote. The derangement was,
however, both slight and temporary: and it is only instructive to us as
showing at what cost such a work as the _Principia_ must be produced,
even by so mighty a mind as that of Newton.
The first part of the work having been done, any ordinary mortal would
have proceeded to publish it; but the fact is that after he had sent to
the Royal Society his papers on optics, there had arisen controversies
and objections; most of them rather paltry, to which he felt compelled
to find answers. Many men would have enjoyed this part of the work, and
taken it as evidence of interest and success. But to Newton's shy and
retiring disposition these discussions were merely painful. He writes,
indeed, his answers with great patience and ability, and ultimately
converts the more reasonable of his opponents, but he relieves his mind
in the following letter to the secretary of the Royal Society: "I see I
have made myself a slave to philosophy, but if I get free of this
present business I will resolutely bid adieu to it eternally, except
what I do for my private satisfaction or leave to come out after me; for
I see a man must either resolve to put out nothing new, or to become a
slave to defend it." And again in a letter to Leibnitz: "I have been so
persecuted with discussions arising out of my theory of light that I
blamed my own imprudence for parting with so substantial a blessing as
my quiet to run after a shadow." This shows how much he cared for
contemporary fame.
So he locked up the first part of the _Principia_ in his desk, doubtless
intending it to be published after his death. But fortunately this was
not so to be.
In 1683, among the leading lights of the Royal Society, the same sort of
notions about gravity and the solar system began independently to be
bruited. The theory of gravitation seemed to be in the air, and Wren,
Hooke, and Halley had many a talk about it.
Hooke showed an experiment with a pendulum, which he likened to a planet
going round the sun. The analogy is more superficial than real. It does
not obey Kepler's laws; still it was a striking experiment. They had
guessed at a law of inverse squares, and their difficulty was to prove
what curve a body subject to it would describe. They knew it ought to be
an ellipse if it was to serve to explain the planetary motion, and Hooke
said he could prove that an ellipse it was; but he was nothing of a
mathematician, and the others scarcely believed him. Undoubtedly he had
shrewd inklings of the truth, though his guesses were based on little
else than a most sagacious intuition. He surmised also that gravity was
the force concerned, and asserted that the path of an ordinary
projectile was an ellipse, like the path of a planet--which is quite
right. In fact the beginnings of the discovery were beginning to dawn
upon him in the well-known way in which things do dawn upon ordinary men
of genius: and had Newton not lived we should doubtless, by the labours
of a long chain of distinguished men, beginning with Hooke, Wren, and
Halley, have been now in possession of all the truths revealed by the
_Principia_. We should never have had them stated in the same form, nor
proved with the same marvellous lucidity and simplicity, but the facts
themselves we should by this time have arrived at. Their developments
and completions, due to such men as Clairaut, Euler, D'Alembert,
Lagrange, Laplace, Airy, Leverrier, Adams, we should of course not have
had to the same extent; because the lives and energies of these great
men would have been partially consumed in obtaining the main facts
themselves.
The youngest of the three questioners at the time we are speaking of was
Edmund Halley, an able and remarkable man. He had been at Cambridge,
doubtless had heard Newton lecture, and had acquired a great veneration
for him.
In January, 1684, we find Wren offering Hooke and Halley a prize, in the
shape of a book worth forty shillings, if they would either of them
bring him within two months a demonstration that the path of a planet
subject to an inverse square law would be an ellipse. Not in two months,
nor yet in seven, was there any proof forthcoming. So at last, in
August, Halley went over to Cambridge to speak to Newton about the
difficult problem and secure his aid. Arriving at his rooms he went
straight to the point. He said, "What path will a body describe if it
be attracted by a centre with a force varying as the inverse square of
the distance." To which Newton at once replied, "An ellipse." "How on
earth do you know?" said Halley in amazement. "Why, I have calculated
it," and began hunting about for the paper. He actually couldn't find it
just then, but sent it him shortly by post, and with it much more--in
fact, what appeared to be a complete treatise on motion in general.
With his valuable burden Halley hastened to the Royal Society and told
them what he had discovered. The Society at his representation wrote to
Mr. Newton asking leave that it might be printed. To this he consented;
but the Royal Society wisely appointed Mr. Halley to see after him and
jog his memory, in case he forgot about it. However, he set to work to
polish it up and finish it, and added to it a great number of later
developments and embellishments, especially the part concerning the
lunar theory, which gave him a deal of trouble--and no wonder; for in
the way he has put it there never was a man yet living who could have
done the same thing. Mathematicians regard the achievement now as men
might stare at the work of some demigod of a bygone age, wondering what
manner of man this was, able to wield such ponderous implements with
such apparent ease.
To Halley the world owes a great debt of gratitude--first, for
discovering the _Principia_; second, for seeing it through the press;
and third, for defraying the cost of its publication out of his own
scanty purse. For though he ultimately suffered no pecuniary loss,
rather the contrary, yet there was considerable risk in bringing out a
book which not a dozen men living could at the time comprehend. It is no
small part of the merit of Halley that he recognized the transcendent
value of the yet unfinished work, that he brought it to light, and
assisted in its becoming understood to the best of his ability.
Though Halley afterwards became Astronomer-Royal, lived to the ripe old
age of eighty-six, and made many striking observations, yet he would be
the first to admit that nothing he ever did was at all comparable in
importance with his discovery of the _Principia_; and he always used to
regard his part in it with peculiar pride and pleasure.
And how was the _Principia_ received? Considering the abstruse nature of
its subject, it was received with great interest and enthusiasm. In less
than twenty years the edition was sold out, and copies fetched large
sums. We hear of poor students copying out the whole in manuscript in
order to possess a copy--not by any means a bad thing to do, however
many copies one may possess. The only useful way really to read a book
like that is to pore over every sentence: it is no book to be skimmed.
While the _Principia_ was preparing for the press a curious incident of
contact between English history and the University occurred. It seems
that James II., in his policy of Catholicising the country, ordered both
Universities to elect certain priests to degrees without the ordinary
oaths. Oxford had given way, and the Dean of Christ Church was a
creature of James's choosing. Cambridge rebelled, and sent eight of its
members, among them Mr. Newton, to plead their cause before the Court of
High Commission. Judge Jeffreys presided over the Court, and threatened
and bullied with his usual insolence. The Vice-Chancellor of Cambridge
was deprived of office, the other deputies were silenced and ordered
away. From the precincts of this court of justice Newton returned to
Trinity College to complete the _Principia_.
By this time Newton was only forty-five years old, but his main work was
done. His method of fluxions was still unpublished; his optics was
published only imperfectly; a second edition of the _Principia_, with
additions and improvements, had yet to appear; but fame had now come
upon him, and with fame worries of all kinds.
By some fatality, principally no doubt because of the interest they
excited, every discovery he published was the signal for an outburst of
criticism and sometimes of attack. I shall not go into these matters:
they are now trivial enough, but it is necessary to mention them,
because to Newton they evidently loomed large and terrible, and
occasioned him acute torment.
[Illustration: FIG. 68.--Newton when young. (_From an engraving by B.
Reading after Sir Peter Lely._)]
No sooner was the _Principia_ put than Hooke put in his claims for
priority. And indeed his claims were not altogether negligible; for
vague ideas of the same sort had been floating in his comprehensive
mind, and he doubtless felt indistinctly conscious of a great deal more
than he could really state or prove.
By indiscreet friends these two great men were set somewhat at
loggerheads, and worse might have happened had they not managed to come
to close quarters, and correspond privately in a quite friendly manner,
instead of acting through the mischievous medium of third parties. In
the next edition Newton liberally recognizes the claims of both Hooke
and Wren. However, he takes warning betimes of what he has to expect,
and writes to Halley that he will only publish the first two books,
those containing general theorems on motion. The third book--concerning
the system of the world, _i.e._ the application to the solar system--he
says "I now design to suppress. Philosophy is such an impertinently
litigious lady that a man had as good be engaged in law-suits as have to
do with her. I found it so formerly, and now I am no sooner come near
her again but she gives me warning. The two books without the third will
not so well bear the title 'Mathematical Principles of Natural
Philosophy,' and therefore I had altered it to this, 'On the Free Motion
of Two Bodies'; but on second thoughts I retain the former title: 'twill
help the sale of the book--which I ought not to diminish now 'tis
yours."
However, fortunately, Halley was able to prevail upon him to publish the
third book also. It is, indeed, the most interesting and popular of the
three, as it contains all the direct applications to astronomy of the
truths established in the other two.
Some years later, when his method of fluxions was published, another and
a worse controversy arose--this time with Leibnitz, who had also
independently invented the differential calculus. It was not so well
recognized then how frequently it happens that two men independently
and unknowingly work at the very same thing at the same time. The
history of science is now full of such instances; but then the friends
of each accused the other of plagiarism.
I will not go into the controversy: it is painful and useless. It only
served to embitter the later years of two great men, and it continued
long after Newton's death--long after both their deaths. It can hardly
be called ancient history even now.
But fame brought other and less unpleasant distractions than
controversies. We are a curious, practical, and rather stupid people,
and our one idea of honouring a man is to _vote_ for him in some way or
other; so they sent Newton to Parliament. He went, I believe, as a Whig,
but it is not recorded that he spoke. It is, in fact, recorded that he
was once expected to speak when on a Royal Commission about some
question of chronometers, but that he would not. However, I dare say he
made a good average member.
Then a little later it was realized that Newton was poor, that he still
had to teach for his livelihood, and that though the Crown had continued
his fellowship to him as Lucasian Professor without the necessity of
taking orders, yet it was rather disgraceful that he should not be
better off. So an appeal was made to the Government on his behalf, and
Lord Halifax, who exerted himself strongly in the matter, succeeding to
office on the accession of William III., was able to make him ultimately
Master of the Mint, with a salary of some L1,200 a year. I believe he
made rather a good Master, and turned out excellent coins: certainly he
devoted his attention to his work there in a most exemplary manner.
But what a pitiful business it all is! Here is a man sent by Heaven to
do certain things which no man else could do, and so long as he is
comparatively unknown he does them; but so soon as he is found out, he
is clapped into a routine office with a big salary: and there is,
comparatively speaking, an end of him. It is not to be supposed that he
had lost his power, for he frequently solved problems very quickly which
had been given out by great Continental mathematicians as a challenge to
the world.
We may ask why Newton allowed himself to be thus bandied about instead
of settling himself down to the work in which he was so pre-eminently
great. Well, I expect your truly great man never realizes how great he
is, and seldom knows where his real strength lies. Certainly Newton did
not know it. He several times talks of giving up philosophy altogether;
and though he never really does it, and perhaps the feeling is one only
born of some temporary overwork, yet he does not sacrifice everything
else to it as he surely must had he been conscious of his own greatness.
No; self-consciousness was the last thing that affected him. It is for a
great man's contemporaries to discover him, to make much of him, and to
put him in surroundings where he may flourish luxuriantly in his own
heaven-intended way.
However, it is difficult for us to judge of these things. Perhaps if he
had been maintained at the national expense to do that for which he was
preternaturally fitted, he might have worn himself out prematurely;
whereas by giving him routine work the scientific world got the benefit
of his matured wisdom and experience. It was no small matter to the
young Royal Society to be able to have him as their President for
twenty-four years. His portrait has hung over the President's chair ever
since, and there I suppose it will continue to hang until the Royal
Society becomes extinct.
The events of his later life I shall pass over lightly. He lived a calm,
benevolent life, universally respected and beloved. His silver-white
hair when he removed his peruke was a venerable spectacle. A lock of it
is still preserved, with many other relics, in the library of Trinity
College. He died quietly, after a painful illness, at the ripe age of
eighty-five. His body lay in state in the Jerusalem Chamber, and he was
buried in Westminster Abbey, six peers bearing the pall. These things
are to be mentioned to the credit of the time and the country; for
after we have seen the calamitous spectacle of the way Tycho and Kepler
and Galileo were treated by their ungrateful and unworthy countries, it
is pleasant to reflect that England, with all its mistakes, yet
recognized _her_ great man when she received him, and honoured him with
the best she knew how to give.
[Illustration: FIG. 69.--Sir Isaac Newton.]
Concerning his character, one need only say that it was what one would
expect and wish. It was characterized by a modest, calm, dignified
simplicity. He lived frugally with his niece and her husband, Mr.
Conduit, who succeeded him as Master of the Mint. He never married, nor
apparently did he ever think of so doing. The idea, perhaps, did not
naturally occur to him, any more than the idea of publishing his work
did.
He was always a deeply religious man and a sincere Christian, though
somewhat of the Arian or Unitarian persuasion--so, at least, it is
asserted by orthodox divines who understand these matters. He studied
theology more or less all his life, and towards the end was greatly
interested in questions of Biblical criticism and chronology. By some
ancient eclipse or other he altered the recognized system of dates a few
hundred years; and his book on the prophecies of Daniel and the
Revelation of St. John, wherein he identifies the beast with the Church
of Rome in quite the orthodox way, is still by some admired.
But in all these matters it is probable that he was a merely ordinary
man, with natural acumen and ability doubtless, but nothing in the least
superhuman. In science, the impression he makes upon me is only
expressible by the words inspired, superhuman.
And yet if one realizes his method of work, and the calm, uninterrupted
flow of all his earlier life, perhaps his achievements become more
intelligible. When asked how he made his discoveries, he replied: "By
always thinking unto them. I keep the subject constantly before me, and
wait till the first dawnings open slowly by little and little into a
full and clear light." That is the way--quiet, steady, continuous
thinking, uninterrupted and unharassed brooding. Much may be done under
those conditions. Much ought to be sacrificed to obtain those
conditions. All the best thinking work of the world has been thus
done.[18] Buffon said: "Genius is patience." So says Newton: "If I have
done the public any service this way, it is due to nothing but industry
and patient thought." Genius patience? No, it is not quite that, or,
rather, it is much more than that; but genius without patience is like
fire without fuel--it will soon burn itself out.
NOTES FOR LECTURE IX
The _Principia_ published 1687.
Newton died 1727.
THE LAW OF GRAVITATION.--Every particle of matter attracts every other
particle of matter with a force proportional to the mass of each and to
the inverse square of the distance between them.
SOME OF NEWTON'S DEDUCTIONS.
1. Kepler's second law (equable description of areas) proves that each
planet is acted on by a force directed towards the sun as a centre of
force.
2. Kepler's first law proves that this central force diminishes in the
same proportion as the square of the distance increases.
3. Kepler's third law proves that all the planets are acted on by the
same kind of force; of an intensity depending on the mass of the
sun.[19]
4. So by knowing the length of year and distance of any planet from the
sun, the sun's mass can be calculated, in terms of that of the earth.
5. For the satellites, the force acting depends on the mass of _their_
central body, a planet. Hence the mass of any planet possessing a
satellite becomes known.