with the contrivance known as the "cross-staff," which he used to
observe the stars whenever opportunity offered. It must, of course,
be remembered that in those days there were no telescopes. In the
absence of optical aid, such as lenses afford the modern observers,
astronomers had to rely on mechanical appliances alone to measure the
places of the stars. Of such appliances, perhaps the most ingenious
was one known before Tycho's time, which we have represented in the
adjoining figure.
[PLATE: TYCHO'S CROSS STAFF.]
Let us suppose that it be desired to measure the angle between two
stars, then if the angle be not too large it can be determined in the
following manner. Let the rod AB be divided into inches and parts of
an inch, and let another rod, CD, slide up and down along AB in such
a way that the two always remain perpendicular to each other.
"Sights," like those on a rifle, are placed at A and C, and there is
a pin at D. It will easily be seen that, by sliding the movable bar
along the fixed one, it must always be possible when the stars are
not too far apart to bring the sights into such positions that one
star can be seen along DC and the other along DA. This having been
accomplished, the length from A to the cross-bar is read off on the
scale, and then, by means of a table previously prepared, the value
of the required angular distance is obtained. If the angle between
the two stars were greater than it would be possible to measure in
the way already described, then there was a provision by which the
pin at D might be moved along CD into some other position, so as to
bring the angular distance of the stars within the range of the
instrument.
[PLATE: TYCHO'S "NEW STAR" SEXTANT OF 1572.
(The arms, of walnut wood, are about 5 1/2 ft. long.)]
No doubt the cross-staff is a very primitive contrivance, but when
handled by one so skilful as Tycho it afforded results of
considerable accuracy. I would recommend any reader who may have a
taste for such pursuits to construct a cross-staff for himself, and
see what measurements he can accomplish with its aid.
To employ this little instrument Tycho had to evade the vigilance of
his conscientious tutor, who felt it his duty to interdict all such
occupations as being a frivolous waste of time. It was when Vedel
was asleep that Tycho managed to escape with his cross staff and
measure the places of the heavenly bodies. Even at this early age
Tycho used to conduct his observations on those thoroughly sound
principles which lie at the foundation of all accurate modern
astronomy. Recognising the inevitable errors of workmanship in his
little instrument, he ascertained their amount and allowed for their
influence on the results which he deduced. This principle, employed
by the boy with his cross-staff in 1564, is employed at the present
day by the Astronomer Royal at Greenwich with the most superb
instruments that the skill of modern opticians has been able to
construct.
[PLATE: TYCHO'S TRIGONIC SEXTANT.
(The arms, AB and AC, are about 5 1/2 ft. long.)]
After the death of his uncle, when Tycho was nineteen years of age,
it appears that the young philosopher was no longer interfered with
in so far as the line which his studies were to take was concerned.
Always of a somewhat restless temperament, we now find that he
shifted his abode to the University of Rostock, where he speedily
made himself notable in connection with an eclipse of the moon on
28th October, 1566. Like every other astronomer of those days, Tycho
had always associated astronomy with astrology. He considered that
the phenomena of the heavenly bodies always had some significance in
connection with human affairs. Tycho was also a poet, and in the
united capacity of poet, astrologer, and astronomer, he posted up
some verses in the college at Rostock announcing that the lunar
eclipse was a prognostication of the death of the great Turkish
Sultan, whose mighty deeds at that time filled men's minds. Presently
news did arrive of the death of the Sultan, and Tycho was accordingly
triumphant; but a little later it appeared that the decease had taken
place BEFORE the eclipse, a circumstance which caused many a laugh at
Tycho's expense.
[PLATE: TYCHO'S ASTRONOMIC SEXTANT.
(Made of steel: the arms, AB, AC, measure 4 ft.)
PLATE: TYCHO'S EQUATORIAL ARMILLARY.
(The meridian circle, E B C A D, made of solid steel,
is nearly 6 ft. in diameter.)]
Tycho being of a somewhat turbulent disposition, it appears that,
while at the University of Rostock, he had a serious quarrel with
another Danish nobleman. We are not told for certain what was the
cause of the dispute. It does not, however, seem to have had any
more romantic origin than a difference of opinion as to which of them
knew the more mathematics. They fought, as perhaps it was becoming
for two astronomers to fight, under the canopy of heaven in utter
darkness at the dead of night, and the duel was honourably terminated
when a slice was taken off Tycho's nose by the insinuating sword of
his antagonist. For the repair of this injury the ingenuity of the
great instrument-maker was here again useful, and he made a
substitute for his nose "with a composition of gold and silver." The
imitation was so good that it is declared to have been quite equal to
the original. Dr. Lodge, however, pointedly observes that it does
not appear whether this remark was made by a friend or an enemy.
[PLATE: THE GREAT AUGSBURG QUADRANT.
(Built of heart of oak; the radii about 19 ft.)
PLATE: TYCHO'S "NEW SCHEME OF THE TERRESTRIAL SYSTEM," 1577.]
The next few years Tycho spent in various places ardently pursuing
somewhat varied branches of scientific study. At one time we hear of
him assisting an astronomical alderman, in the ancient city of
Augsburg, to erect a tremendous wooden machine--a quadrant of 19-feet
radius--to be used in observing the heavens. At another time we
learn that the King of Denmark had recognised the talents of his
illustrious subject, and promised to confer on him a pleasant
sinecure in the shape of a canonry, which would assist him with the
means for indulging his scientific pursuits. Again we are told that
Tycho is pursuing experiments in chemistry with the greatest energy,
nor is this so incompatible as might at first be thought with his
devotion to astronomy. In those early days of knowledge the
different sciences seemed bound together by mysterious bonds.
Alchemists and astrologers taught that the several planets were
correlated in some mysterious manner with the several metals. It
was, therefore hardly surprising that Tycho should have included a
study of the properties of the metals in the programme of his
astronomical work.
[PLATE: URANIBORG AND ITS GROUNDS.
PLATE: GROUND-PLAN OF THE OBSERVATORY.]
An event, however, occurred in 1572 which stimulated Tycho's
astronomical labours, and started him on his life's work. On the
11th of November in that year, he was returning home to supper after
a day's work in his laboratory, when he happened to lift his face to
the sky, and there he beheld a brilliant new star. It was in the
constellation of Cassiopeia, and occupied a position in which there
had certainly been no bright star visible when his attention had last
been directed to that part of the heavens. Such a phenomenon was so
startling that he found it hard to trust the evidence of his senses.
He thought he must be the subject of some hallucination. He
therefore called to the servants who were accompanying him, and asked
them whether they, too, could see a brilliant object in the direction
in which he pointed. They certainly could, and thus he became
convinced that this marvellous object was no mere creation of the
fancy, but a veritable celestial body--a new star of surpassing
splendour which had suddenly burst forth. In these days of careful
scrutiny of the heavens, we are accustomed to the occasional outbreak
of new stars. It is not, however, believed that any new star which
has ever appeared has displayed the same phenomenal brilliance as was
exhibited by the star of 1572.
This object has a value in astronomy far greater than it might at
first appear. It is true, in one sense, that Tycho discovered the
new star, but it is equally true, in a different sense, that it was
the new star which discovered Tycho. Had it not been for this
opportune apparition, it is quite possible that Tycho might have
found a career in some direction less beneficial to science than that
which he ultimately pursued.
[PLATE: THE OBSERVATORY OF URANIBORG, ISLAND OF HVEN.]
When he reached his home on this memorable evening, Tycho immediately
applied his great quadrant to the measurement of the place of the new
star. His observations were specially directed to the determination
of the distance of the object. He rightly conjectured that if it
were very much nearer to us than the stars in its vicinity, the
distance of the brilliant body might be determined in a short time by
the apparent changes in its distance from the surrounding points. It
was speedily demonstrated that the new star could not be as near as
the moon, by the simple fact that its apparent place, as compared
with the stars in its neighbourhood, was not appreciably altered when
it was observed below the pole, and again above the pole at an
interval of twelve hours. Such observations were possible, inasmuch
as the star was bright enough to be seen in full daylight. Tycho
thus showed conclusively that the body was so remote that the
diameter of the earth bore an insignificant ratio to the star's
distance. His success in this respect is the more noteworthy when we
find that many other observers, who studied the same object, came to
the erroneous conclusion that the new star was quite as near as the
moon, or even much nearer. In fact, it may be said, that with regard
to this object Tycho discovered everything which could possibly have
been discovered in the days before telescopes were invented. He not
only proved that the star's distance was too great for measurement,
but he showed that it had no proper motion on the heavens. He
recorded the successive changes in its brightness from week to week,
as well as the fluctuations in hue with which the alterations in
lustre were accompanied.
It seems, nowadays, strange to find that such thoroughly scientific
observations of the new star as those which Tycho made, possessed,
even in the eyes of the great astronomer himself, a profound
astrological significance. We learn from Dr. Dreyer that, in Tycho's
opinion, "the star was at first like Venus and Jupiter, and its
effects will therefore, first, be pleasant; but as it then became
like Mars, there will next come a period of wars, seditions,
captivity, and death of princes, and destruction of cities, together
with dryness and fiery meteors in the air, pestilence, and venomous
snakes. Lastly, the star became like Saturn, and thus will finally
come a time of want, death, imprisonment, and all kinds of sad
things!" Ideas of this kind were, however, universally entertained.
It seemed, indeed, obvious to learned men of that period that such an
apparition must forebode startling events. One of the chief theories
then held was, that just as the Star of Bethlehem announced the first
coming of Christ, so the second coming, and the end of the world, was
heralded by the new star of 1572.
The researches of Tycho on this object were the occasion of his first
appearance as an author. The publication of his book was however,
for some time delayed by the urgent remonstrances of his friends, who
thought it was beneath the dignity of a nobleman to condescend to
write a book. Happily, Tycho determined to brave the opinion of his
order; the book appeared, and was the first of a series of great
astronomical productions from the same pen.
[PLATE: EFFIGY ON TYCHO'S TOMB AT PRAGUE.]
The fame of the noble Dane being now widespread, the King of Denmark
entreated him to return to his native country, and to deliver a
course of lectures on astronomy in the University of Copenhagen. With
some reluctance he consented, and his introductory oration has been
preserved. He dwells, in fervent language, upon the beauty and the
interest of the celestial phenomena. He points out the imperative
necessity of continuous and systematic observation of the heavenly
bodies in order to extend our knowledge. He appeals to the practical
utility of the science, for what civilised nation could exist without
having the means of measuring time? He sets forth how the study of
these beautiful objects "exalts the mind from earthly and trivial
things to heavenly ones;" and then he winds up by assuring them that
"a special use of astronomy is that it enables us to draw conclusions
from the movements in the celestial regions as to human fate."
An interesting event, which occurred in 1572, distracted Tycho's
attention from astronomical matters. He fell in love. The young
girl on whom his affections were set appears to have sprung from
humble origin. Here again his august family friends sought to
dissuade him from a match they thought unsuitable for a nobleman.
But Tycho never gave way in anything. It is suggested that he did
not seek a wife among the highborn dames of his own rank from the
dread that the demands of a fashionable lady would make too great an
inroad on the time that he wished to devote to science. At all
events, Tycho's union seems to have been a happy one, and he had a
large family of children; none of whom, however, inherited their
father's talents.
[PLATE: TYCHO'S MURAL QUADRANT PICTURE, URANIBORG.]
Tycho had many scientific friends in Germany, among whom his work was
held in high esteem. The treatment that he there met with seemed to
him so much more encouraging than that which he received in Denmark
that he formed the notion of emigrating to Basle and making it his
permanent abode. A whisper of this intention was conveyed to the
large-hearted King of Denmark, Frederick II. He wisely realised how
great would be the fame which would accrue to his realm if he could
induce Tycho to remain within Danish territory and carry on there the
great work of his life. A resolution to make a splendid proposal to
Tycho was immediately formed. A noble youth was forthwith despatched
as a messenger, and ordered to travel day and night until he reached
Tycho, whom he was to summon to the king. The astronomer was in bed
on the morning of 11th February, 1576, when the message was
delivered. Tycho, of course, set off at once and had an audience of
the king at Copenhagen. The astronomer explained that what he wanted
was the means to pursue his studies unmolested, whereupon the king
offered him the Island of Hven, in the Sound near Elsinore. There he
would enjoy all the seclusion that he could desire. The king further
promised that he would provide the funds necessary for building a
house and for founding the greatest observatory that had ever yet
been reared for the study of the heavens. After due deliberation and
consultation with his friends, Tycho accepted the king's offer. He
was forthwith granted a pension, and a deed was drawn up formally
assigning the Island of Hven to his use all the days of his life.
The foundation of the famous castle of Uraniborg was laid on 30th
August, 1576. The ceremony was a formal and imposing one, in
accordance with Tycho's ideas of splendour. A party of scientific
friends had assembled, and the time had been chosen so that the
heavenly bodies were auspiciously placed. Libations of costly wines
were poured forth, and the stone was placed with due solemnity. The
picturesque character of this wonderful temple for the study of the
stars may be seen in the figures with which this chapter is
illustrated.
One of the most remarkable instruments that has ever been employed in
studying the heavens was the mural quadrant which Tycho erected in
one of the apartments of Uraniborg. By its means the altitudes of
the celestial bodies could be observed with much greater accuracy
than had been previously attainable. This wonderful contrivance is
represented on the preceding page. It will be observed that the
walls of the room are adorned by pictures with a lavishness of
decoration not usually to be found in scientific establishments.
A few years later, when the fame of the observatory at Hven became
more widely spread, a number of young men flocked to Tycho to study
under his direction. He therefore built another observatory for
their use in which the instruments were placed in subterranean rooms
of which only the roofs appeared above the ground. There was a
wonderful poetical inscription over the entrance to this underground
observatory, expressing the astonishment of Urania at finding, even
in the interior of the earth, a cavern devoted to the study of the
heavens. Tycho was indeed always fond of versifying, and he lost no
opportunity of indulging this taste whenever an occasion presented
itself.
Around the walls of the subterranean observatory were the pictures of
eight astronomers, each with a suitable inscription--one of these of
course represented Tycho himself, and beneath were written words to
the effect that posterity should judge of his work. The eighth
picture depicted an astronomer who has not yet come into existence.
Tychonides was his name, and the inscription presses the modest hope
that when he does appear he will be worthy of his great predecessor.
The vast expenses incurred in the erection and the maintenance of
this strange establishment were defrayed by a succession of grants
from the royal purse.
For twenty years Tycho laboured hard at Uraniborg in the pursuit of
science. His work mainly consisted in the determination of the
places of the moon, the planets, and the stars on the celestial
sphere. The extraordinary pains taken by Tycho to have his
observations as accurate as his instruments would permit, have justly
entitled him to the admiration of all succeeding astronomers. His
island home provided the means of recreation as well as a place for
work. He was surrounded by his family, troops of friends were not
wanting, and a pet dwarf seems to have been an inmate of his curious
residence. By way of change from his astronomical labours he used
frequently to work with his students in his chemical laboratory. It
is not indeed known what particular problems in chemistry occupied
his attention. We are told, however, that he engaged largely in the
production of medicines, and as these appear to have been dispensed
gratuitously there was no lack of patients.
Tycho's imperious and grasping character frequently brought him into
difficulties, which seem to have increased with his advancing years.
He had ill-treated one of his tenants on Hven, and an adverse
decision by the courts seems to have greatly exasperated the
astronomer. Serious changes also took place in his relations to the
court at Copenhagen. When the young king was crowned in 1596, he
reversed the policy of his predecessor with reference to Hven. The
liberal allowances to Tycho were one after another withdrawn, and
finally even his pension was stopped. Tycho accordingly abandoned
Hven in a tumult of rage and mortification. A few years later we
find him in Bohemia a prematurely aged man, and he died on the 24th
October, 1601.
GALILEO.
Among the ranks of the great astronomers it would be difficult to
find one whose life presents more interesting features and remarkable
vicissitudes than does that of Galileo. We may consider him as the
patient investigator and brilliant discoverer. We may consider him
in his private relations, especially to his daughter, Sister Maria
Celeste, a woman of very remarkable character; and we have also the
pathetic drama at the close of Galileo's life, when the philosopher
drew down upon himself the thunders of the Inquisition.
The materials for the sketch of this astonishing man are sufficiently
abundant. We make special use in this place of those charming
letters which his daughter wrote to him from her convent home. More
than a hundred of these have been preserved, and it may well be
doubted whether any more beautiful and touching series of letters
addressed to a parent by a dearly loved child have ever been
written. An admirable account of this correspondence is contained in
a little book entitled "The Private Life of Galileo," published
anonymously by Messrs. Macmillan in 1870, and I have been much
indebted to the author of that volume for many of the facts contained
in this chapter.
Galileo was born at Pisa, on 18th February, 1564. He was the eldest
son of Vincenzo de' Bonajuti de' Galilei, a Florentine noble.
Notwithstanding his illustrious birth and descent, it would seem that
the home in which the great philosopher's childhood was spent was an
impoverished one. It was obvious at least that the young Galileo
would have to be provided with some profession by which he might earn
a livelihood. From his father he derived both by inheritance and by
precept a keen taste for music, and it appears that he became an
excellent performer on the lute. He was also endowed with
considerable artistic power, which he cultivated diligently. Indeed,
it would seem that for some time the future astronomer entertained
the idea of devoting himself to painting as a profession. His
father, however, decided that he should study medicine. Accordingly,
we find that when Galileo was seventeen years of age, and had added a
knowledge of Greek and Latin to his acquaintance with the fine arts,
he was duly entered at the University of Pisa.
Here the young philosopher obtained some inkling of mathematics,
whereupon he became so much interested in this branch of science,
that he begged to be allowed to study geometry. In compliance with
his request, his father permitted a tutor to be engaged for this
purpose; but he did so with reluctance, fearing that the attention of
the young student might thus be withdrawn from that medical work
which was regarded as his primary occupation. The event speedily
proved that these anxieties were not without some justification. The
propositions of Euclid proved so engrossing to Galileo that it was
thought wise to avoid further distraction by terminating the
mathematical tutor's engagement. But it was too late for the desired
end to be attained. Galileo had now made such progress that he was
able to continue his geometrical studies by himself. Presently he
advanced to that famous 47th proposition which won his lively
admiration, and on he went until he had mastered the six books of
Euclid, which was a considerable achievement for those days.
The diligence and brilliance of the young student at Pisa did not,
however, bring him much credit with the University authorities. In
those days the doctrines of Aristotle were regarded as the embodiment
of all human wisdom in natural science as well as in everything
else. It was regarded as the duty of every student to learn
Aristotle off by heart, and any disposition to doubt or even to
question the doctrines of the venerated teacher was regarded as
intolerable presumption. But young Galileo had the audacity to think
for himself about the laws of nature. He would not take any
assertion of fact on the authority of Aristotle when he had the means
of questioning nature directly as to its truth or falsehood. His
teachers thus came to regard him as a somewhat misguided youth,
though they could not but respect the unflagging industry with which
he amassed all the knowledge he could acquire.
[PLATE: GALILEO'S PENDULUM.]