explains the rising, southing, and setting of the whole visible
firmament. The effect of the annual motion, _i.e._ of the apparent
annual motion, of the sun among the stars, is less obvious, but it may
be followed easily enough by observing the stars visible at any given
time of evening at different seasons of the year. At midnight, for
instance, the position of the sun is definite, viz. due north always,
but the constellation which at that time is due south or is rising or
setting varies with the time of year; an interval of one month producing
just the same effect on the appearance of the constellations as an
interval of two hours does (because the day contains twice as many hours
as the year contains months), _e.g._ the sky looks the same at midnight
on the 1st of October as it does at 10 p.m. on the 1st of November.
All these simple consequences of the geocentric as opposed to the
heliocentric point of view were pointed out by Copernicus, in addition
to his greater work of constructing improved planetary tables on the
basis of his theory. But it must be admitted that he himself felt the
hypothesis of the motion of the earth to be a difficulty. Its acceptance
is by no means such an easy and childish matter as we are apt now to
regard it, and the hostility to it is not at all surprising. The human
race, after having ridiculed and resisted the truth for a long time, is
apt to end in accepting it so blindly and unimaginatively as to fail to
recognize the real achievement of its first propounders, or the
difficulties which they had to overcome. The majority of men at the
present day have grown accustomed to hear the motion of the earth spoken
of: their acceptance of it means nothing: the attitude of the paradoxer
who denies it is more intelligent.
It is not to be supposed that the idea of thus explaining some of the
phenomena of the heavens, especially the daily motion of the entire
firmament, by a diurnal rotation of the earth had not struck any one. It
was often at this time referred to as the Pythagorean theory, and it had
been taught, I believe, by Aristarchus. But it was new to the modern
world, and it had the great weight of Aristotle against it.
Consequently, for long after Copernicus, only a few leading spirits
could be found to support it, and the long-established venerable
Ptolemaic system continued to be taught in all Universities.
The main objections to the motion of the earth were such as the
following:--
1. The motion is unfelt and difficult to imagine.
That it is unfelt is due to its uniformity, and can be explained
mechanically. That it is difficult to imagine is and remains true,
but a most important lesson we have to learn is that difficulty of
conception is no valid argument against reality.
2. That the stars do not alter their relative positions according to
the season of the year, but the constellations preserve always the same
aspect precisely, even to careful measurement.
This is indeed a difficulty, and a great one. In June the earth is
184 million miles away from where it was in December: how can we
see precisely the same fixed stars? It is not possible, unless they
are at a practically infinite distance. That is the only answer
that can be given. It was the tentative answer given by Copernicus.
It is the correct answer. Not only from every position of the
earth, but from every planet of the solar system, the same
constellations are visible, and the stars have the same aspect. The
whole immensity of the solar system shrinks to practically a point
when confronted with the distance of the stars.
Not, however, so entirely a speck as to resist the terrific
accuracy of the present century, and their microscopic relative
displacement with the season of the year has now at length been
detected, and the distance of many thereby measured.
3. That, if the earth revolved round the sun, Mercury and Venus ought to
show phases like the moon.
So they ought. Any globe must show phases if it live nearer the sun
than we do and if we go round it, for we shall see varying amounts
of its illuminated half. The only answer that Copernicus could give
to this was that they might be difficult to see without extra
powers of sight, but he ventured to predict that the phases would
be seen if ever our powers of vision should be enhanced.
4. That if the earth moved, or even revolved on its own axis, a stone or
other dropped body ought to be left far behind.
This difficulty is not a real one, like the two last, and it is
based on an ignorance of the laws of mechanics, which had not at
that time been formulated. We know now that a ball dropped from a
high tower, so far from lagging, drops a minute trifle _in front_
of the foot of a perpendicular, because the top of the tower is
moving a trace faster than the bottom, by reason of the diurnal
rotation. But, ignoring this, a stone dropped from the lamp of a
railway carriage drops in the centre of the floor, whether the
carriage be moving steadily or standing still; a slant direction of
fall could only be detected if the carriage were being accelerated
or if the brake were applied. A body dropped from a moving carriage
shares the motion of the carriage, and starts with that as its
initial velocity. A ball dropped from a moving balloon does not
simply drop, but starts off in whatever direction the car was
moving, its motion being immediately modified by gravity, precisely
in the same way as that of a thrown ball is modified. This is,
indeed, the whole philosophy of throwing--to drop a ball from a
moving carriage. The carriage is the hand, and, to throw far, a run
is taken and the body is jerked forward; the arm is also moved as
rapidly as possible on the shoulder as pivot. The fore-arm can be
moved still faster, and the wrist-joint gives yet another motion:
the art of throwing is to bring all these to bear at the same
instant, and then just as they have all attained their maximum
velocity to let the ball go. It starts off with the initial
velocity thus imparted, and is abandoned to gravity. If the vehicle
were able to continue its motion steadily, as a balloon does, the
ball when let go from it would appear to the occupant simply to
drop; and it would strike the ground at a spot vertically under the
moving vehicle, though by no means vertically below the place where
it started. The resistance of the air makes observations of this
kind inaccurate, except when performed inside a carriage so that
the air shares in the motion. Otherwise a person could toss and
catch a ball out of a train window just as well as if he were
stationary; though to a spectator outside he would seem to be using
great skill to throw the ball in the parabola adapted to bring it
back to his hand.
The same circumstance enhances the apparent difficulty of the
circus rider's jumping feats. All he has to do is to jump up and
down on the horse; the forward motion which carries him through
hoops belongs to him by virtue of the motion of the horse, without
effort on his part.
Thus, then, it happens that a stone dropped sixteen feet on the
earth appears to fall straight down, although its real path in
space is a very flat trajectory of nineteen miles base and sixteen
feet height; nineteen miles being the distance traversed by the
earth every second in the course of its annual journey round the
sun.
No wonder that it was thought that bodies must be left behind if
the earth was subject to such terrific speed as this. All that
Copernicus could suggest on this head was that perhaps the
atmosphere might help to carry things forward, and enable them to
keep pace with the earth.
There were thus several outstanding physical difficulties in the way of
the acceptance of the Copernican theory, besides the Biblical
difficulty.
It was quite natural that the idea of the earth's motion should be
repugnant, and take a long time to sink into the minds of men; and as
scientific progress was vastly slower then than it is now, we find not
only all priests but even some astronomers one hundred years afterwards
still imagining the earth to be at rest. And among them was a very
eminent one, Tycho Brahe.
It is interesting to note, moreover, that the argument about the motion
of the earth being contrary to Scripture appealed not only to
ecclesiastics in those days, but to scientific men also; and Tycho
Brahe, being a man of great piety, and highly superstitious also, was so
much influenced by it, that he endeavoured to devise some scheme by
which the chief practical advantages of the Copernican system could be
retained, and yet the earth be kept still at the centre of the whole.
This was done by making all the celestial sphere, with stars and
everything, rotate round the earth once a day, as in the Ptolemaic
scheme; and then besides this making all the planets revolve round the
sun, and this to revolve round the earth. Such is the Tychonic system.
So far as _relative_ motion is concerned it comes to the same thing;
just as when you drop a book you may say either that the earth rises to
meet the book, or that the book falls to meet the earth. Or when a fly
buzzes round your head, you may say that you are revolving round the
fly. But the absurdity of making the whole gigantic system of sun and
planets and stars revolve round our insignificant earth was too great to
be swallowed by other astronomers after they had once had a taste of the
Copernican theory; and accordingly the Tychonic system died a speedy and
an easy death at the same time as its inventor.
Wherein then lay the magnitude of the man?--not in his theories, which
were puerile, but in his observations, which were magnificent. He was
the first observational astronomer, the founder of the splendid system
of practical astronomy which has culminated in the present Greenwich
Observatory.
[Illustration: FIG. 16.--Tychonic system showing the sun with all the
planets revolving round the earth.]
Up to Tycho the only astronomical measurements had been of the rudest
kind. Copernicus even improved upon what had gone before, with measuring
rules made with his own hands. Ptolemy's observations could never be
trusted to half a degree. Tycho introduced accuracy before undreamed of,
and though his measurements, reckoned by modern ideas, are of course
almost ludicrously rough (remember no such thing as a telescope or
microscope was then dreamed of), yet, estimated by the era in which they
were made, they are marvels of accuracy, and not a single mistake due
to carelessness has ever been detected in them. In fact they may be
depended on almost to minutes of arc, _i.e._ to sixtieths of a degree.
For certain purposes connected with the proper motion of stars they are
still appealed to, and they served as the certain and trustworthy data
for succeeding generations of theorists to work upon. It was long,
indeed, after Tycho's death before observations approaching in accuracy
to his were again made.
In every sense, therefore, he was a pioneer: let us proceed to trace his
history.
Born the eldest son of a noble family--"as noble and ignorant as sixteen
undisputed quarterings could make them," as one of his biographers
says--in a period when, even more than at present, killing and hunting
were the only natural aristocratic pursuits, when all study was regarded
as something only fit for monks, and when science was looked at askance
as something unsavoury, useless, and semi-diabolic, there was little in
his introduction to the world urging him in the direction where his
genius lay. Of course he was destined for a soldier; but fortunately his
uncle, George Brahe, a more educated man than his father, having no son
of his own, was anxious to adopt him, and though not permitted to do so
for a time, succeeded in getting his way on the birth of a second son,
Steno--who, by the way, ultimately became Privy Councillor to the King
of Denmark.
Tycho's uncle gave him what he would never have got at home--a good
education; and ultimately put him to study law. At the age of thirteen
he entered the University of Copenhagen, and while there occurred the
determining influence of his life.
An eclipse of the sun in those days was not regarded with the
cold-blooded inquisitiveness or matter-of-fact apathy, according as
there is or is not anything to be learnt from it, with which such an
event is now regarded. Every occurrence in the heavens was then
believed to carry with it the destiny of nations and the fate of
individuals, and accordingly was of surpassing interest. Ever since the
time of Hipparchus it had been possible for some capable man here and
there to predict the occurrence of eclipses pretty closely. The thing is
not difficult. The prediction was not, indeed, to the minute and second,
as it is now; but the day could usually be hit upon pretty accurately
some time ahead, much as we now manage to hit upon the return of a
comet--barring accidents; and the hour could be predicted as the event
approached.
Well, the boy Tycho, among others, watched for this eclipse on August
21st, 1560; and when it appeared at its appointed time, every instinct
for the marvellous, dormant in his strong nature, awoke to strenuous
life, and he determined to understand for himself a science permitting
such wonderful possibilities of prediction. He was sent to Leipzig with
a tutor to go on with his study of law, but he seems to have done as
little law as possible: he spent all his money on books and instruments,
and sat up half the night studying and watching the stars.
In 1563 he observed a conjunction of Jupiter and Saturn, the precursor,
and _cause_ as he thought it, of the great plague. He found that the old
planetary tables were as much as a month in error in fixing this event,
and even the Copernican tables were several days out; so he formed the
resolve to devote his life to improving astronomical tables. This
resolve he executed with a vengeance. His first instrument was a jointed
ruler with sights for fixing the position of planets with respect to the
stars, and observing their stations and retrogressions. By thus
measuring the angles between a planet and two fixed stars, its position
can be plotted down on a celestial map or globe.
[Illustration: FIG. 17.--Portrait of Tycho.]
In 1565 his uncle George died, and made Tycho his heir. He returned to
Denmark, but met with nothing but ridicule and contempt for his absurd
drivelling away of time over useless pursuits. So he went back to
Germany--first to Wittenberg, thence, driven by the plague, to Rostock.
Here his fiery nature led him into an absurd though somewhat dangerous
adventure. A quarrel at some feast, on a mathematical point, with a
countryman, Manderupius, led to the fixing of a duel, and it was fought
with swords at 7 p.m. at the end of December, when, if there was any
light at all, it must have been of a flickering and unsatisfactory
nature. The result of this insane performance was that Tycho got his
nose cut clean off.
He managed however to construct an artificial one, some say of gold and
silver, some say of putty and brass; but whatever it was made of there
is no doubt that he wore it for the rest of his life, and it is a most
famous feature. It excited generally far more interest than his
astronomical researches. It is said, moreover, to have very fairly
resembled the original, but whether this remark was made by a friend or
by an enemy I cannot say. One account says that he used to carry about
with him a box of cement to apply whenever his nose came off, which it
periodically did.
About this time he visited Augsburg, met with some kindred and
enlightened spirits in that town, and with much enthusiasm and spirit
constructed a great quadrant. These early instruments were tremendous
affairs. A great number of workmen were employed upon this quadrant, and
it took twenty men to carry it to its place and erect it. It stood in
the open air for five years, and then was destroyed by a storm. With it
he made many observations.
[Illustration: FIG. 18.--Early out-door quadrant of Tycho; for
observing altitudes by help of the sights _D_, _L_ and the plumb line.]
On his return to Denmark in 1571, his fame preceded him, and he was
much better received; and in order to increase his power of constructing
instruments he took up the study of alchemy, and like the rest of the
persuasion tried to make gold. The precious metals were by many old
philosophers considered to be related in some way to the heavenly
bodies: silver to the moon, for instance--as we still see by the name
lunar caustic applied to nitrate of silver; gold to the sun, copper to
Mars, lead to Saturn. Hence astronomy and alchemy often went together.
Tycho all his life combined a little alchemy with his astronomical
labours, and he constructed a wonderful patent medicine to cure all
disorders, which had as wide a circulation in Europe in its time as
Holloway's pills; he gives a tremendous receipt for it, with liquid gold
and all manner of ingredients in it; among them, however, occurs a
little antimony--a well-known sudorific--and to this, no doubt, whatever
efficacy the medicine possessed was due.
So he might have gone on wasting his time, were it not that in November,
1572, a new star made its appearance, as they have done occasionally
before and since. On the average one may say that about every fifty
years a new star of fair magnitude makes its temporary appearance. They
are now known to be the result of some catastrophe or collision, whereby
immense masses of incandescent gas are produced. This one seen by Tycho
became as bright as Jupiter, and then died away in about a year and a
half. Tycho observed all its changes, and endeavoured to measure its
distance from the earth, with the result that it was proved to belong to
the region of the fixed stars, at an immeasurable distance, and was not
some nearer and more trivial phenomenon.
He was asked by the University of Copenhagen to give a course of
lectures on astronomy; but this was a step he felt some aristocratic
aversion to, until a little friendly pressure was brought to bear upon
him by a request from the king, and delivered they were.
He now seems to have finally thrown off his aristocratic prejudices, and
to have indulged himself in treading on the corns of nearly all the high
and mighty people he came into contact with. In short, he became what we
might now call a violent Radical; but he was a good-hearted man,
nevertheless, and many are the tales told of his visits to sick
peasants, of his consulting the stars as to their fate--all in perfect
good faith--and of the medicines which he concocted and prescribed for
them.
The daughter of one of these peasants he married, and very happy the
marriage seems to have been.
[Illustration: FIG. 19.--Map of Denmark, showing the island of Huen.
_Walker & Boutallse._]
Now comes the crowning episode in Tycho's life. Frederick II., realizing
how eminent a man they had among them, and how much he could do if only
he had the means--for we must understand that Tycho, though of good
family and well off, was by no means what we would call a wealthy
man--Frederick II. made him a splendid and enlightened offer. The offer
was this: that if Tycho would agree to settle down and make his
astronomical observations in Denmark, he should have an estate in Norway
settled upon him, a pension of L400 a year for life, a site for a large
observatory, and L20,000 to build it with.
[Illustration: FIG. 20.--Uraniburg.]
[Illustration: FIG. 21.--Astrolabe. An old instrument with sights for
marking the positions of the celestial bodies roughly. A sort of
skeleton celestial globe.]
[Illustration:
SEXTANS ASTRONOMICVS
TRIGONICVS PRO DISTANTIIS
rimandis.
FIG. 22.--Tycho's large sextant; for measuring the angular distance
between two bodies by direct sighting.]
Well, if ever money was well spent, this was. By its means Denmark
before long headed the nations of Europe in the matter of science--a
thing it has not done before or since. The site granted was the island
of Huen, between Copenhagen and Elsinore; and here the most magnificent
observatory ever built was raised, and called Uraniburg--the castle of
the heavens. It was built on a hill in the centre of the island, and
included gardens, printing shops, laboratory, dwelling-houses, and four
observatories--all furnished with the most splendid instruments that
Tycho could devise, and that could then be constructed. It was decorated
with pictures and sculptures of eminent men, and altogether was a most
gorgeous place. L20,000 no doubt went far in those days, but the
original grant was supplemented by Tycho himself, who is said to have
spent another equal sum out of his own pocket on the place.
[Illustration: QVADRANS MAXIMVS CHALIBEUS QUADRATO INCLUSUS, ET
Horizonti Azimuthali chalybeo insistens.
FIG. 23.--The Quadrant in Uraniburg; or altitude and azimuth
instrument.]
For twenty years this great temple of science was continually worked in
by him, and he soon became the foremost scientific man in Europe.
Philosophers, statesmen, and occasionally kings, came to visit the great
astronomer, and to inspect his curiosities.
[Illustration:
QVADRANS MVRALIS
SIVE TICHONICUS.
FIG. 24.--Tycho's form of transit circle.
The method of utilising the extremely uniform rotation of the earth by
watching the planets and stars as they cross the meridian, and recording
their times of transit; observing also at the same time their meridian
altitudes (see observer _F_), was the invention of Tycho, and
constitutes his greatest achievement. His method is followed to this day
in all observatories.]
[Illustration: FIG. 25.--A modern transit circle, showing essentially
the same parts as in Tycho's instrument, viz. the observer watching the
transit, the clock, the recorder of the observation, and the graduated
circle; the latter to be read by a second observer.]
And very wholesome for some of these great personages must have been the
treatment they met with. For Tycho was no respecter of persons. His
humbly-born wife sat at the head of the table, whoever was there; and he
would snub and contradict a chancellor just as soon as he would a serf.
Whatever form his pride may have taken when a youth, in his maturity it
impelled him to ignore differences of rank not substantially justified,
and he seemed to take a delight in exposing the ignorance of shallow
titled persons, to whom contradiction and exposure were most unusual
experiences.
For sick peasants he would take no end of trouble, and went about
doctoring them for nothing, till he set all the professional doctors
against him; so that when his day of misfortune came, as come it did,
their influence was not wanting to help to ruin one who spoilt their
practice, and whom they derided as a quack.
But some of the great ignorant folk who came to visit his temple of
science, and to inspect its curiosities, felt themselves insulted--not
always without reason. He kept a tame maniac in the house, named Lep,
and he used to regard the sayings of this personage as oracular,
presaging future events, and far better worth listening to than ordinary
conversation. Consequently he used to have him at his banquets and feed
him himself; and whenever Lep opened his mouth to speak, every one else
was peremptorily ordered to hold his tongue, so that Lep's words might
be written down. In fact it was something like an exaggerated edition of
Betsy Trotwood and Mr. Dick.
"It must have been an odd dinner party" (says Prof. Stuart), "with this
strange, wild, terribly clever man, with his red hair and brazen nose,
sometimes flashing with wit and knowledge, sometimes making the whole
company, princes and servants alike, hold their peace and listen humbly
to the ravings of a poor imbecile."
To people he despised he did not show his serious instruments. He had
other attractions, in the shape of a lot of toy machinery, little
windmills, and queer doors, and golden globes, and all manner of
ingenious tricks and automata, many of which he had made himself, and
these he used to show them instead; and no doubt they were well enough
pleased with them. Those of the visitors, however, who really cared to
see and understand his instruments, went away enchanted with his genius
and hospitality.