Page:The Gradual Acceptance of the Copernican Theory of the Universe.djvu/88

 from my particular position toward the Holy, Catholic and Apostolic Church."

This monumental work, the most important literary production of the Society in the 17th century, is abundant witness to Riccioli's remarkable erudition and industry. Nearly one-fifth of the total bulk of the two huge volumes is devoted to a statement of the Copernican controversy. This is prefaced by a brief account of his own theory of the universe—the invention of which is another proof of the ability of the man—for his scientific training prevented his acceptance of the Aristotelian-Ptolemaic theory in the light of Galileo's discoveries; his position as a Jesuit and a faithful son of the Church precluded him from adopting the system condemned by its representatives; and Tycho Brahe's scheme was not wholly to his liking. Therefor he proposed an adaptation of the last-named, more in accordance, as he thought, with the facts. Where Tycho had all the planets except the earth and the moon encircle the sun, and that in turn, together with the moon and the sphere of the fixed stars, sweep around the earth as the center of the universe, Riccioli made only Mars, Mercury and Venus encircle the sun,—Mars with an orbit the radius of which included the earth within its sweep, the other two planets with orbital radii shorter than that of the sun, and so excluding the earth. This he did, (1) because both Jupiter and Saturn have their own kingdoms in the heavens, and Mars, Mercury and Venus are but satellites of the sun; (2) because there are greater varieties of eccentricity among these three than the other two; (3) because Saturn and Jupiter are the greatest planets and with the sphere of the fixed stars move more slowly; (4) Mars belongs with the sun because of their related movements; and (5) because it is likely that one of the planets would have much in common both with Saturn and Jupiter and with Mercury and Venus also.

Then he takes up the attack upon the Copernican doctrine. M. Delambre summarizes and comments upon 57 of his arguments

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