Page:Popular Science Monthly Volume 51.djvu/701

Rh errors in the reasoning of Apelles concerning the direction of the sun's rotation.

In Mario Welser's first letter to Galileo, dated January 6, 1612, he asks Galileo's opinion concerning the spots discovered by Scheiner, and forwards three of the latter's famous letters. Three months afterward (May 4, 1612) Galileo answers him in a very long letter, saying that he has been observing the spots for eighteen months, that he has shown them to several friends, and has besides within a year exhibited them to many prelates and lords at Rome. According to this, he must have seen the spots as early as the end of November, 1610; and the discovery, or first observation, must have been as early as the summer of 1610, or before Galileo removed from Venice to Florence, the change of residence taking place at the end of August, 1610. It is proved, in fact, by a letter from the friar Fulgence Servita, a theologian of the Most Serene Republic, that he showed the spots to Father Paolo. It is not easy to divine why Galileo, usually so careful of his rights, did not this time make a claim for priority in discovery; but it may be supposed that by the side of the discovery of the Medici stars, Saturn's rings, and the phases of Venus, that of dark points on the sun, changing in character and disappearing according to the position of the star, appeared of trifling importance to him; and this is to a certain extent confirmed by the reply to Welser. Galileo's observations, in fact, did not begin to be known till in 1612; and if we did not trust to his assertions or to ocular testimony, Fabricius, Scheiner, and perhaps others, made the discovery before him; but this would not be a fair judgment. It must be admitted that Galileo first observed the spots on the sun with the aid of the Lippersheim glass; but his earliest notices on the subject did not appear till the spring of 1612, while the earliest publication on it is that of Fabricius, who discovered the spots on March 9, 1611, in complete ignorance that Galileo had observed them eight months before.

The false Apelles pretended that he had observed the spots for the first time, together with one of his pupils, in March, 1611. How, then, could Kepler have written to David Fabricius of "the sun spots seen by your son long before, Apelles," if, as we know now, Jean discovered them in March, 1611? No one was more in the current of events than Kepler, and he was astonished at the letters of Apelles. Besides, Scheiner told Welser that he had observed some darkish things on the sun, but attached no importance to them till October, when he resumed his observations—that is, after Jean Fabricius's book had been published.

It finally appears from Dr. Berthold's book that (1) Galileo was the first to observe the spots on the sun with the Lippersheim telescope in the summer of 1610, but he did not publish his