Galileo and the Telescope

Excerpts from “Galileo and the Telescope,”
From Historic Inventions (1911)
by Rupert Sargent Holland

For centuries the laws of mechanics as laid down by the Greek Aristotle had been accepted without much dispute by the civilized world.  But a spirit of new thought and investigation was now rising in Europe, and more especially in Italy.  Galileo determined to study the laws of mechanics by experiment, and not, as so many earlier scientists had done, by argument or mere theoretical opinions.  Therefore he undertook to establish definitely the laws relating to falling bodies.

Aristotle, almost two thousand years before, had announced that if two bodies of different weights were dropped from the same height the heavier would reach the ground sooner than the lighter, according to the proportion of their weights.  Galileo doubted this, and decided to try it.  Accordingly he assembled the teachers and students of the university one morning about the base of the famous Leaning Tower of Pisa.  He himself climbed to the top, carrying with him a ten-pound shot and a one-pound shot.  He balanced them on the edge of the tower and let them fall together.  They struck the ground together.  As a result of this experiment Galileo declared three laws in relation to falling bodies.  He said that if one neglected the resistance of the air, or in other words supposed the bodies to fall through a vacuum, it would be found, first, that all bodies fall from the same height in equal times; second, that in falling the final velocities are proportional to the times; and third, that the spaces fallen through are proportional to the squares of the times.

The first of these laws was shown by his experiment on the Leaning Tower.  To show the others he built a straight inclined plane with a groove down its centre.  A bronze ball was free to move in the groove with the least possible friction.  By means of this he showed that no matter how much he inclined the plane, and so changed the time, the ball would always move down it according to the laws he had stated.

But in disproving the accuracy of the old laws of Aristotle the young scientist has raised a hornet’s nest about his ears.  The men of the old school would not believe him, a conspiracy was set on foot against him, and finally the criticism of his new teachings grew so severe that he was forced to resign his position, and move to Florence . . .

Galileo’s fame as a teacher had now spread widely throughout Europe, and students began to flock to Padua to study under him . . . [Galileo] shortly began to lecture on the comparatively new science of astronomy.  Formerly he had taught the old system of Aristotle to his classes, now, after a searching investigation, he declared his belief in the contrary conclusions of Copernicus.  This study led him on and on . . . All educated men were rousing to the fact that the age was fertile with new discoveries in every branch of knowledge . . .

The telescope that Galileo presented to the Doge of Venice, and which was later lost, consisted of a tube. He used this to examine the moon . . .  But this last telescope did not altogether satisfy him, and so he built a still larger one . . . With this he discovered the moons of Jupiter, and some of the fixed stars, and added much to what was already known concerning the Milky Way . . .

As the voyage of Columbus had brought a new world in the western ocean to the notice of Europe, so Galileo’s discoveries with his telescope brought forth a new world in the skies.  Galileo wrote out statements of his discoveries, and sent these, with his new telescopes, to the princes and learned men of Italy, France, Flanders, and Germany.  At all the courts and universities the telescopes were received with the greatest enthusiasm, and put to instant use in the hope of discovering new stars.  But again the followers of Aristotle, those who were unwilling to admit that anything new could be learned about the laws of nature or the universe, arose in wrath.  They attacked Galileo and his discoveries.  They would not admit that Jupiter had four attendant moons, although these satellites could be seen by any one through the telescope, and a little later, when Galileo stated that the planet Saturn was composed of three stars which touched each other (later found to be one planet with two rings) they rose up to denounce him.  But as yet these protests against the discoverer had little effect.  Europe was too much interested in what he was showing it to realize how deeply it might affect men’s views of the universe.

Fame was now safely his.  Men came from all parts of Europe to study under this wonderful professor of Padua.  But teaching gave him too little time to carry on his own researches.  So he looked about for some other position that would give him greater leisure, and finally stated his wishes to Cosimo II, Duke of Florence.  Galileo had named the satellites of Jupiter after the house of Medici, to which this Duke belonged, and Cosimo was much flattered at the compliment . . . .

Settled at last at Florence his work as an astronomer steadily went forward.  He discovered that the planet Venus had a varying crescent form, that there were small spots circling across the face of the sun, which he called sun-spots, and later that there were mountains on the moon.  He also visited Rome, where he was received with the greatest good-will by Pope Paul V and his cardinals, and where he met leading scientists of the capital.

But Galileo’s course was no less flecked with light and shade than were the sun and moon he studied.  The envy of rivals soon spread false reports about him, and the professors at Pisa refused to accept the results of his studies.  Then one of the latter stirred the religious scruples of the Dowager Grand Duchess by telling her that Galileo’s conclusion that the earth had a double motion must be wrong, since it was opposed to the statements of the Bible.  Galileo heard of this, and wrote a letter in reply, in which he said that in studying the laws of nature men must start with what they could prove by experiments instead of relying wholly on the Scriptures.  This was enough to set the machinery of his enemies in motion.  Galileo’s teachings were pointed out as dangerous to the teachings of the Church, and the officers of the Inquisition began to consider how they might best deal with him.  Certain of his writings were declared false and prohibited, and he was admonished that he must follow certain lines in his teachings.  He went to Rome himself, and saw the Pope again, but found his friends were fewer and his enemies growing more powerful.

The theory of Copernicus that the earth and planets are in constant motion was the very foundation of Galileo’s scientific studies, and yet the order of the Church now forbade him to use this theory.  He went back to Florence out of health and despondent . . . He wrote out the results of his discoveries . . .

In 1632 he published what he called “The Dialogues of Galileo Galilei.”  This divided the world of Italy into two camps, the one those who believed in Aristotle and the old learning, the other those who followed Copernicus, Galileo, and Kepler.  The Jesuits took up the gage he had thrown down, and Galileo found the Church of Rome arrayed against him.  The sale of his book was forbidden, a commission was appointed to bring charges against him, and he was ordered to go to Rome for trial.  The commission reported that Galileo had disobeyed the Church’s orders by maintaining that the earth moves and that the sun is stationary . . .

The Inquisition did its work ruthlessly.  Notices of the sentence prohibiting the reading of Galileo’s book and ordering all copies of it to be surrendered, and copies of the declaration he had made denying his former teachings, were sent to all of the courts of Europe and to many of the universities . . . Thus the humiliation was spread broadcast, and in addition he was ordered to be held at Rome as a prisoner . . .

Galileo made many great discoveries and inventions; there was hardly a field of science that he did not enter and explore; but his greatest work was to open a new world to men’s attention.  It was this that brought him before the Inquisition and that branded him as a dangerous heretic, and it was this that placed him in the forefront of the world’s discoverers.  Men might say that the earth stood still, because it suited them best to believe so, but Galileo gave the world an instrument by which it could study the matter for itself, and the world had gone on using that instrument and that method ever since.
[pp. 55-69]

1. Briefly summarize the overall impression given in these excerpts of Galileo’s encounter with the Church.
2. How does this portrayal of Galileo DIFFER from the account in [J] and in class?
3. Evaluate & analyze the following statement: “The best description of Galileo’s conflict with the Church is “science” battling against “religion.”