[19] Edin. Phil. Journ. 1822, vol. vi. p. 317. See Rigaud's Life of Bradley, Supplement, p. 31.

[20] Id. It., p. 37, 38.

Another candidate for the honour of discovering the spots of the sun, was John Fabricius, who undoubtedly saw them previous to June 1611. The dedication of the work[21] in which he has recorded his observation, bears the date of the 13th of June 1611; and it is obvious, from the work itself, that he had seen the spots about the end of the year 1610; but as there is no proof that he saw them before October, we are compelled to a.s.sign the priority of the discovery to the Italian astronomer.

[21] Joh. Fabricii Phrysii de Maculis in Sole observatis, et apparente earum c.u.m Sole conversione, Narratio. Wittemb. 1611.

The claim of Scheiner, professor of mathematics at Ingolstadt, is more intimately connected with the history of Galileo. This learned astronomer having, early in 1611, turned his telescope to the sun, necessarily discovered the spots which at that time covered his disc.

Light flying clouds happened, at the time, to weaken the intensity of his light, so that he was able to show the spots to his pupils. These observations were not published till January 1612; and they appeared in the form of three letters, addressed to Mark Velser, one of the magistrates of Augsburg, under the signature of _Appelles post Tabulam_.

Scheiner, who, many years afterwards, published an elaborate work on the subject, adopted the same idea which had at first occurred to Galileo--that the spots were the dark sides of planets revolving round and near the sun.[22]

[22] It does not appear from the history of solar observations at what time, and by whom, coloured gla.s.ses were first introduced for permitting the eye to look at the sun with impunity. Fabricius was obviously quite ignorant of the use of coloured gla.s.ses. He observed the sun when he was in the horizon, and when his brilliancy was impaired by the interposition of thin clouds and floating vapours; and he advises those who may repeat his observations to admit at first to the eye a small portion of the sun's light, till it is gradually accustomed to its full splendour.

When the sun's alt.i.tude became considerable, Fabricius gave up his observations, which he often continued so long that he was scarcely able, for two days together, to see objects with their usual distinctness. Fabricius speaks of observing the sun by admitting his rays through a small _hole_ into a dark room, and receiving his image on paper; but he says nothing about a lens or a telescope being applied to the hole; and he does not say that he saw the spots of the sun in this way. Harriot also viewed the solar spots when the sun was near the horizon, or was visible through "thick layer and thin cloudes," or through thin mist. On December 21, 1611, at a quarter past 2 P.M., he observed the spots when the sky was perfectly clear, but his "sight was after dim for an houre."

Scheiner, in his "Appelles post Tabulam," describes four different ways of viewing the spots; one of which is by the _interposition of blue or green gla.s.ses_. His first method was to observe the sun near the horizon; the second was to view him through a transparent cloud; the third was to look at him through his telescope with a blue or a green gla.s.s of a proper thickness, and plane on both sides, or to use a thin blue gla.s.s when the sun was covered with a thin vapour or cloud; and the fourth method was to begin and observe the sun at his margin, till the eye gradually reached the middle of his disc.

On the publication of Scheiner's letters, Velser transmitted a copy of them to his friend Galileo, with the request that he would favour him with his opinion of the new phenomena. After some delay, Galileo addressed three letters to Velser, in which he combated the opinions of Scheiner on the cause of the spots. The first of these letters was dated the 4th of May 1612;[23] but though the controversy was carried on in the language of mutual respect and esteem, it put an end to the friendship which had existed between the two astronomers. In these letters Galileo showed that the spots often dispersed like vapours or clouds; that they sometimes had a duration of only one or two days, and at other times of thirty or forty days; that they contracted in their breadth when they approached the sun's limb, without any diminution of their length; that they describe circles parallel to each other; that the monthly rotation of the sun again brings the same spots into view; and that they are seldom seen at a greater distance than 30 from the sun's equator. Galileo likewise discovered on the sun's disc _faculae_, or _luculi_, as they were called, which differ in no respect from the common ones but in their being brighter than the rest of the sun's surface.[24]

[23] The original of this letter is in the British Museum.

[24] See Istoria e Dimonstrazioni, intorno alle macchie solare.

_Roma_, 1616. See Opere di Galileo, vol, v., p. 131-293.

In the last of the letters which our author addressed to Velser, and which was written in December 1612, he recurs to his former discovery of the elongated shape, or rather the triple structure, of Saturn. The singular figure which he had observed in this planet had entirely disappeared; and he evidently announces the fact to Velser, lest it should be used by his enemies to discredit the accuracy of his observations. "Looking on Saturn," says he, "within these few days, I found it solitary, without the a.s.sistance of its accustomed stars, and, in short, perfectly round and defined like Jupiter; and such it still remains. Now, what can be said of so strange a metamorphosis? Are the two smaller stars consumed like the spots on the sun? Have they suddenly vanished and fled? or has Saturn devoured his own children? or was the appearance indeed fraud and illusion, with which the gla.s.ses have for so long a time mocked me, and so many others who have often observed with me? Now, perhaps, the time is come to revive the withering hopes of those who, guided by more profound contemplations, have followed all the fallacies of the new observations, and recognised their impossibilities.

I cannot resolve what to say in a chance so strange, so new, and so unexpected; the shortness of the time, the unexampled occurrence, the weakness of my intellect, and the terror of being mistaken, have greatly confounded me." Although Galileo struggled to obtain a solution of this mystery, yet he had not the good fortune to succeed. He imagined that the two smaller stars would reappear, in consequence of the supposed revolution of the planet round its axis; but the discovery of the ring of Saturn, and of the obliquity of its plane to the ecliptic, was necessary to explain the phenomena which were so perplexing to our author.

The ill health to which Galileo was occasionally subject, and the belief that the air of Florence was prejudicial to his complaints, induced him to spend much of his time at Selve, the villa of his friend Salviati.

This eminent individual had ever been the warmest friend of Galileo, and seems to have delighted in drawing round him the scientific genius of the age. He was a member of the celebrated Lyncaean Society, founded by Prince Frederigo Cesi; and though he is not known as the author of any important discovery, yet he has earned, by his liberality to science, a glorious name, which will be indissolubly united with the immortal destiny of Galileo.

The subject of floating bridges having been discussed at one of the scientific parties which had a.s.sembled at the house of Salviati, a difference of opinion arose respecting the influence of the shape of bodies on their disposition to float or to sink in a fluid. Contrary to the general opinion, Galileo undertook to prove that it depended on other causes; and he was thus led to compose his discourse on floating bodies,[25] which was published in 1612, and dedicated to Cosmo de Medici. This work contains many ingenious experiments, and much acute reasoning in support of the true principles of hydrostatics; and it is now chiefly remarkable as a specimen of the sagacity and intellectual power of its author. Like all his other works, it encountered the most violent opposition; and Galileo was more than once summoned into the field to repel the aggressions of his ignorant and presumptuous opponents. The first attack upon it was made by Ptolemy Nozzolini, in a letter to Marzemedici, Archbishop of Florence;[26] and to this Galileo replied in a letter addressed to his antagonist.[27] A more elaborate examination of it was published by Lodovico delle Colombe, and another by M. Vincenzo di Grazia. To these attacks, a minute and overwhelming answer was printed in the name of Benedetti Castelli, the friend and pupil of Galileo; but it was discovered, some years after Galileo's death, that he was himself the author of this work.[28]

[25] Discorso intorno alle cose che stanno in su l'acqua, o che in quella si muovono. Opere di Galileo, vol. ii. pp. 165-311.

[26] Opere di Galileo, vol. ii. pp. 355-367.

[27] Ibid. 367-390.

[28] These three treatises occupy the whole of the third volume of the Opere di Galileo.

CHAPTER IV.

_Galileo treats his opponents with severity and sarcasm--He is aided by the sceptics of the day--The Church party the most powerful--Galileo commences the attack, and is answered by Caccini, a Dominican--Galileo's Letter to the Grand d.u.c.h.ess of Tuscany, in support of the motion of the Earth and the stability of the Sun--- Galileo visits Rome--Is summoned before the Inquisition, and renounces his opinions as heretical--The Inquisition denounces the Copernican System--Galileo has an audience of the Pope, but still maintains his opinions in private society--Proposes to find out the Longitude at Sea by means of Jupiter's Satellites--His negociation on this subject with the Court of Spain--Its failure--He is unable to observe the three Comets of 1618, but is involved in the controversy to which they gave rise._

The current of Galileo's life had hitherto flowed in a smooth and un.o.bstructed channel. He had now attained the highest objects of earthly ambition. His discoveries had placed him at the head of the great men of the age; he possessed a professional income far beyond his wants, and even beyond his antic.i.p.ations; and, what is still dearer to a philosopher, he enjoyed the most perfect leisure for carrying on and completing his discoveries. The opposition which these discoveries encountered, was to him more a subject for triumph than for sorrow.

Prejudice and ignorance were his only enemies; and if they succeeded for a while in hara.s.sing his march, it was only to lay a foundation for fresh achievements. He who contends for truths which he has himself been permitted to discover, may well sustain the conflict in which presumption and error are destined to fall. The public tribunal may neither be sufficiently pure nor enlightened to decide upon the issue; but he can appeal to posterity, and reckon with confidence on "its sure decree."

The ardour of Galileo's mind, the keenness of his temper, his clear perception of truth, and his inextinguishable love of it, combined to exasperate and prolong the hostility of his enemies. When argument failed to enlighten their judgment, and reason to dispel their prejudices, he wielded against them his powerful weapons of ridicule and sarcasm; and in this unrelenting warfare, he seems to have forgotten that Providence had withheld from his enemies those very gifts which he had so liberally received. He who is allowed to take the start of his species, and to penetrate the veil which conceals from common minds the mysteries of nature, must not expect that the world will be patiently dragged at the chariot wheels of his philosophy. Mind has its inertia as well as matter; and its progress to truth can only be insured by the gradual and patient removal of the obstructions which surround it.

The boldness--may we not say the recklessness--with which Galileo insisted upon making proselytes of his enemies, served but to alienate them from the truth. Errors thus a.s.sailed speedily entrench themselves in general feelings, and become embalmed in the virulence of the pa.s.sions. The various cla.s.ses of his opponents marshalled themselves for their mutual defence. The Aristotelian professors, the temporising Jesuits, the political churchmen, and that timid but respectable body who at all times dread innovation, whether it be in religion or in science, entered into an alliance against the philosophical tyrant who threatened them with the penalties of knowledge.

The party of Galileo, though weak in numbers, was not without power and influence. He had trained around him a devoted band, who idolised his genius and cherished his doctrines. His pupils had been appointed to several of the princ.i.p.al professorships in Italy. The enemies of religion were on this occasion united with the Christian philosopher; and there were, even in these days, many princes and n.o.bles who had felt the inconvenience of ecclesiastical jurisdiction, and who secretly abetted Galileo in his crusade against established errors.

Although these two parties had been long dreading each others power, and reconnoitring each others position, yet we cannot exactly determine which of them hoisted the first signal for war. The church party, particularly its highest dignitaries, were certainly disposed to rest on the defensive. Flanked on one side by the logic of the schools, and on the other by the popular interpretation of Scripture, and backed by the strong arm of the civil power, they were not disposed to interfere with the prosecution of science, however much they may have dreaded its influence. The philosophers, on the contrary, united the zeal of innovators with that firmness of purpose which truth alone can inspire.

Victorious in every contest, they were flushed with success, and they panted for a struggle in which they knew they must triumph.

In this state of warlike preparation Galileo addressed a letter, in 1613, to his friend and pupil, the Abbe Castelli, the object of which was to prove that the Scriptures were not intended to teach us science and philosophy. Hence he inferred, that the language employed in the sacred volume in reference to such subjects should be interpreted only in its common acceptation; and that it was in reality as difficult to reconcile the Ptolemaic as the Copernican system to the expressions which occur in the Bible.

A demonstration was about this time made by the opposite party, in the person of Caccini, a Dominican friar, who made a personal attack upon Galileo from the pulpit. This violent ecclesiastic ridiculed the astronomer and his followers, by addressing them sarcastically in the sacred language of Scripture--"Ye men of _Galilee_, why stand ye here looking up into heaven?" But this species of warfare was disapproved of even by the church; and Luigi Maraffi, the general of the Dominicans, not only apologised to Galileo, who had transmitted to him a formal complaint against Caccini, but expressed the acuteness of his own feelings on being implicated in the "brutal conduct of thirty or forty thousand monks."

From the character of Caccini, and the part which he afterwards played in the persecution of Galileo, we can scarcely avoid the opinion that his attack from the pulpit was intended as a snare for the unwary philosopher. It roused Galileo from his wonted caution; and stimulated, no doubt, by the nature of the answer which he received from Maraffi, he published a long letter of seventy pages, defending and ill.u.s.trating his former views respecting the influence of scriptural language on the two contending systems. As if to give the impress of royal authority to this new appeal, he addressed it to Christian, Grand d.u.c.h.ess of Tuscany, the mother of Cosmo; and in this form it seems to have excited a new interest, as if it had expressed the opinion of the grand ducal family.

These external circ.u.mstances gave additional weight to the powerful and unanswerable reasoning which this letter contains; and it was scarcely possible that any man, possessed of a sound mind, and willing to learn the truth, should refuse his a.s.sent to the judicious views of our author. He expresses his belief that the Scriptures were designed to instruct mankind respecting their salvation, and that the faculties of our minds were given us for the purpose of investigating the phenomena of nature. He considers Scripture and nature as proceeding from the same divine author, and, therefore, incapable of speaking a different language; and he points out the absurdity of supposing that professors of astronomy will shut their eyes to the phenomena which they discover in the heavens, or will refuse to believe those deductions of reason which appeal to their judgment with all the power of demonstration. He supports these views by quotations from the ancient fathers; and he refers to the dedication of Copernicus's own work to the Roman Pontiff, Paul III., as a proof that the Pope himself did not regard the new system of the world as hostile to the sacred writings. Copernicus, on the contrary, tells his Holiness, that the reason of inscribing to him his new system was, that the authority of the Pontiff might put to silence the calumnies of some individuals, who attacked it by arguments drawn from pa.s.sages of Scripture twisted for their own purpose.

It was in vain to meet such reasoning by any other weapons than those of the civil power. The enemies of Galileo saw that they must either crush the dangerous innovation, or allow it the fullest scope; and they determined upon an appeal to the inquisition. Lorini, a monk of the Dominican order, had already denounced to this body Galileo's letter to Castelli; and Caccini, bribed by the mastership of the convent of St Mary of Minerva, was invited to settle at Rome for the purpose of embodying the evidence against Galileo.

Though these plans had been carried on in secret, yet Galileo's suspicions were excited; and he obtained leave from Cosmo to go to Rome about the end of 1615.[29] Here he was lodged in the palace of the Grand Duke's amba.s.sador, and kept up a constant correspondence with the family of his patron at Florence; but, in the midst of this external splendour, he was summoned before the inquisition to answer for the heretical doctrines which he had published. He was charged with maintaining the motion of the earth, and the stability of the sun--with teaching this doctrine to his pupils--with corresponding on the subject with several German mathematicians--and with having published it, and attempted to reconcile it to Scripture, in his letters to Mark Velser in 1612. The inquisition a.s.sembled to consider these charges on the 25th of February 1615; and it was decreed that Galileo should be enjoined by Cardinal Bellarmine to renounce the obnoxious doctrines, and to pledge himself that he would neither teach, defend, nor publish them in future.

In the event of his refusing to acquiesce in this sentence, it was decreed that he should be thrown into prison. Galileo did not hesitate to yield to this injunction. On the day following, the 26th of February, he appeared before Cardinal Bellarmine, to renounce his heretical opinions; and, having declared that he abandoned the doctrine of the earth's motion, and would neither defend nor teach it, in his conversation or in his writings, he was dismissed from the bar of the inquisition.

[29] It is said that Galileo was cited to appear at Rome on this occasion; and the opinion is not without foundation.

Having thus disposed of Galileo, the inquisition conceived the design of condemning the whole system of Copernicus as heretical. Galileo, with more hardihood than prudence, remained at Rome for the purpose of giving his a.s.sistance in frustrating this plan; but there is reason to think that he injured by his presence the very cause which he meant to support. The inquisitors had determined to put down the new opinions; and they now inserted among the prohibited books Galileo's letters to Castelli and the Grand d.u.c.h.ess, Kepler's epitome of the Copernican theory, and Copernicus's own work on the revolutions of the heavenly bodies.

Notwithstanding these proceedings, Galileo had an audience of the Pope, Paul V., in March 1616. He was received very graciously, and spent nearly an hour with his Holiness. When they were about to part, the Pope a.s.sured Galileo, that the congregation were not disposed to receive upon light grounds any calumnies which might be propagated by his enemies, and that, as long as he occupied the papal chair, he might consider himself as safe.

These a.s.surances were no doubt founded on the belief that Galileo would adhere to his pledges; but so bold and inconsiderate was he in the expression of his opinions, that even in Rome he was continually engaged in controversial discussions. The following very interesting account of these disputes is given by Querenghi, in a letter to the Cardinal D'Este:--

"Your eminence would be delighted with Galileo if you heard him holding forth, as he often does, in the midst of fifteen or twenty, all violently attacking him, sometimes in one house, sometimes in another.

But he is armed after such fashion that he laughs all of them to scorn; and even if the novelty of his opinions prevents entire persuasion, he at least convicts of emptiness most of the arguments with which his adversaries endeavour to overwhelm him. He was particularly admirable on Monday last in the house of Signor Frederico Ghisilieri; and what especially pleased me was, that before replying to the contrary arguments, he amplified and enforced them with new grounds of great plausibility, so as to leave his adversaries in a more ridiculous plight, when he afterwards overturned them all."

The discovery of Jupiter's satellites suggested to Galileo a new method of finding the longitude at sea. Philip III. had encouraged astronomers to direct their attention to this problem, by offering a reward for its solution; and in those days, when new discoveries in science were sometimes rejected as injurious to mankind, it was no common event to see a powerful sovereign courting the a.s.sistance of astronomers in promoting the commercial interests of his empire. Galileo seems to have regarded the solution of this problem as an object worthy of his ambition; and he no doubt antic.i.p.ated the triumph which he would obtain over his enemies, if the Medicean stars, which they had treated with such contempt, could be made subservient to the great interests of mankind. During his residence at Rome in 1615 and 1616, Galileo had communicated his views on this subject to the Comte di Lemos, the Viceroy of Naples, who had presided over the council of the Spanish Indies. This n.o.bleman advised him to apply to the Spanish minister the Duke of Lerma; and, through the influence of the Grand Duke Cosmo, his amba.s.sador at the court of Madrid was engaged to manage the affair. The anxiety of Galileo on this subject was singularly great. He a.s.sured the Tuscan amba.s.sador that, in order to accomplish this object, "he was ready to leave all his comforts, his country, his friends, and his family, to cross over into Spain, and to stay as long as he might be wanted at Seville or at Lisbon, or wherever it might be convenient to communicate a knowledge of his method." The lethargy of the Spanish court seems to have increased with the enthusiasm of Galileo; and though the negotiations were occasionally revived for ten or twelve years, yet no steps were taken to bring them to a close. This strange procrastination has been generally ascribed to jealousy or indifference on the part of Spain; but Nelli, one of Galileo's biographers, declares, on the authority of Florentine records, that Cosmo had privately requested from the government the privilege of sending annually to the Spanish Indies two Leghorn merchantmen free of duty, as a compensation for the loss of Galileo!

The failure of this negotiation must have been a source of extreme mortification to the high spirit and sanguine temperament of Galileo.

He had calculated, however, too securely on his means of putting the new method to a successful trial. The great imperfection of the time-keepers of that day, and the want of proper telescopes, would have baffled him in all his efforts, and he would have been subject to a more serious mortification from the failure and rejection of his plan, than that which he actually experienced from the avarice of his patron, or the indifference of Spain. Even in the present day, no telescope has been invented which is capable of observing at sea the eclipses of Jupiter's satellites; and though this method of finding the longitude has great advantages on sh.o.r.e, yet it has been completely abandoned at sea, and superseded by easier and more correct methods.

In the year 1618, when no fewer than _three_ comets visited our system, and attracted the attention of all the astronomers of Europe, Galileo was unfortunately confined to his bed by a severe illness; but, though he was unable to make a single observation upon these remarkable bodies, he contrived to involve himself in the controversies which they occasioned. Marco Guiducci, an astronomer of Florence, and a friend of Galileo, had delivered a discourse on comets before the Florentine Academy. The heads of this discourse, which was published in 1619,[30]

were supposed to have been communicated to him by Galileo, and this seems to have been universally admitted during the controversy to which it gave rise. The opinion maintained in this treatise, that comets are nothing but meteors which occasionally appear in our atmosphere, like halos and rainbows, savours so little of the sagacity of Galileo that we should be disposed to question its paternity. His inability to partake in the general interest which these three comets excited, and to employ his powerful telescope in observing their phenomena, and their movements, might have had some slight share in the formation of an opinion which deprived them of their importance as celestial bodies.

But, however this may have been, the treatise of Guiducci afforded a favourable point of attack to Galileo's enemies, and the dangerous task was entrusted to Horatio Gra.s.si, a learned Jesuit, who, in a work ent.i.tled _The Astronomical and Philosophical Balance_, criticised the discourse on comets, under the feigned name of Lotario Sarsi.

[30] Discorso delle Comete. Printed in the Opere di Galileo, vol.

vi., pp. 117-191.

Galileo replied to this attack in a volume ent.i.tled _Il Saggiatore_, or _The a.s.sayer_, which, owing to the state of his health, was not published till the autumn of 1623.[31] This work was written in the form of a letter to Virginio Cesarini, a member of the Lyncaean Academy, and master of the chamber to Urban VIII., who had just ascended the papal throne. It was dedicated to the Pontiff himself, and has been long celebrated among literary men for the beauty of its language, though it is doubtless one of the least important of Galileo's writings.

[31] Printed in the Opere di Galileo, vol. vi., pp. 191-571.