Great Astronomers by Robert Stawell Ball (best ereader for students .txt) 📖

astronomy. The first

discovery that was made in this direction appears to have been

connected with the number of the stars. Galileo saw to his

amazement that through his little tube he could count ten

times as many stars in the sky as his unaided eye could detect.

Here was, indeed, a surprise. We are now so familiar with the

elementary facts of astronomy that it is not always easy to

realise how the heavens were interpreted by the observers in

those ages prior to the invention of the telescope. We can

hardly, indeed, suppose that Galileo, like the majority of those

who ever thought of such matters, entertained the erroneous

belief that the stars were on the surface of a sphere at equal

distances from the observer. No one would be likely to have

retained his belief in such a doctrine when he saw how the number

of visible stars could be increased tenfold by means of Galileo’s

telescope. It would have been almost impossible to refuse to

draw the inference that the stars thus brought into view were

still more remote objects which the telescope was able to reveal,

just in the same way as it showed certain ships to the astonished

Venetians, when at the time these ships were beyond the reach of

unaided vision.

 

Galileo’s celestial discoveries now succeeded each other rapidly.

That beautiful Milky Way, which has for ages been the object of

admiration to all lovers of nature, never disclosed its true

nature to the eye of man till the astronomer of Padua turned on it

his magic tube. The splendid zone of silvery light was then

displayed as star-dust scattered over the black background of

the sky. It was observed that though the individual stars were

too small to be seen severally without optical aid, yet such was

their incredible number that the celestial radiance produced that

luminosity with which every stargazer was so familiar.

 

But the greatest discovery made by the telescope in these early

days, perhaps, indeed, the greatest discovery that the telescope

has ever accomplished, was the detection of the system of four

satellites revolving around the great planet Jupiter. This

phenomenon was so wholly unexpected by Galileo that, at first,

he could hardly believe his eyes. However, the reality of the

existence of a system of four moons attending the great planet

was soon established beyond all question. Numbers of great

personages crowded to Galileo to see for themselves this beautiful

miniature representing the sun with its system of revolving

planets.

 

Of course there were, as usual, a few incredulous people who

refused to believe the assertion that four more moving bodies

had to be added to the planetary system. They scoffed at the

notion; they said the satellites may have been in the telescope,

but that they were not in the sky. One sceptical philosopher is

reported to have affirmed, that even if he saw the moons of

Jupiter

himself he would not believe in them, as their existence was

contrary to the principles of 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 atronomer’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