whither he returned after his sojourn at Leyden. The telescope was discovered in Holland in 1608 by the optician Jean Lippersheim, of Middelbourg, who immediately applied to the States General for a patent. Jean Fabricius learned of the discovery at Leyden, and took the instrument to Osteel, where his father was, and with it found the sun spots. Nothing is known of him after the publication of the book on the sun spots already mentioned (1611), except that he practiced medicine at Marienhave, near Osteel, and died there probably about 1617. If the Prognosticon for 1618 had not been lost, we should doubtless have had some details respecting his death. In the lack of other sources of knowledge, there is left us the eulogy addressed by Kepler to David Fabrcius: "But also reading in your Prognosticon for the year 1618, by which I am better informed concerning his [Jean's] too early death," etc.; and further on, "But, indeed, there is this excellent little book concerning the solar spots in the year 1611," etc. The author gives particulars concerning the first day of the discovery, the method of observation by projection, and the conclusions which Jean, aided by his father's advice, drew (spots fixed in the body of the sun) concerning the sun's rotation around an axis. Neither the Narration nor the writings of David, so far as they are known to us, give any hints concerning the exact date of the discovery, so that we were confined to guesses till M. Berthold found the Prognosticon of David for 1615, which gave the 27th of February (9th of March N. S.), 1611, as the exact date of the event. Furthermore, a letter from David to Maestlin says that the Narration appeared at the time of the autumn fair of 1611, and this is confirmed by Kepler.
At this point in his learned essay Dr. Berthold discusses the question of priority, for which a claim was earnestly pressed as against Galileo by the Jesuit Scheiner, who assumed the name of Apelles. It is really very singular, as it appears to the author, that not a word was said of Jean Fabricius in this controversy, and it might be inferred that both contestants alike knew nothing of the Narration, but for certain considerations and facts adduced by Dr. Berthold which make this supposition exceedingly improbable, if not impossible.
It is proper to observe here that after the telescope was invented all the discoveries in celestial objects became, as it were, matters of course, and that, whatever noise might be made about them at first, the merit of the observers is insignificant in comparison with that of the calculators who knew how to reason out the basis of the true system. Even if it should be proved that Galileo learned of the existence of the spots from Fabricius's Narration, or from the letters of the false Apelles, the remarkable fact remains that in his first reply to Welser he corrects the
