214

HTSTOEY OF PHYSICAL ASTEONOMY.

who was Professor of Mathematics in the University of Ingolstadt . Thisindividual published an account of his observations in three letters ad-dressed to Wilser, the chief magistrate of Augsburg, under the anonymoussignature of Apelles latens post tabulam. The first of these letters isdated the 12th November, 1611. The author states that he first dis-covered the spots seven months previously. This assertion would carryback his observations to the month of April, 1611. He mentions that,upon resuming his observations in the month of October, he suspectedthat the appearances arose from some defect in the glasses with which heviewed the sun, but that after he had prosecuted his observations for ashort time he finally became convinced of the actual existence of the spots * * * § .With respect to his alleged discovery of the spots as early as April, 1611,it i3 clearly inadmissible, inasmuch as it rests solely on his own assertion.Nor, indeed, even if supported by sufficient evidence, do his observationsof that period appear to possess any real merit, since we find him inOctober still doubting the actual existence of the spots. Galileo firstalluded to his discovery of the solar spots in the commencement of his“Dissertation on Floating Bodies,” published at Florence in 1612f. Adetailed account of his researches on these phenomena is contained inthree letters addressed to Welser in reply to the letters addressed to thesame individual by Schemer, whose views of the nature of the solar spotswere at variance with those of the Italian philosopher. These letterswere published at Rome in January, 1613, under the auspices of thecelebrated Lyncean Society J. The first letter is dated the 4th May, 1612.The author asserts in it that eighteen months had elapsed since heoriginally observed the spots. This statement carries back his discoveryto about the beginning of November, 1610. As, however, he has notcited any observations of so early a date, nor mentioned any individuals towhom he communicated his discovery, it is impossible to admit his asser-tion as an historical fact§. Evidence of a more reliable character goes to

* An amusing incident is related in connexion with Scheiner’s observations, whichindicates the fatal effect with which the authority of Aristotle succeeded in maintaining itsascendancy over men’s minds, even when the dogmas of the illustrious Stagyrite wereopposed to the testimony of the senses. As soon as Scheiner had assured himself of theactual existence of the solar spots, he communicated his discovery to the Provincial of theOrder of Jesuits , but the latter, who was a zealous Peripatician, positively refused to givecredit to his assertion. “ I have read Aristotle ’s writings from end to end many times,”says he to Scheiner, “and I can assure you that I have nowhere found in them anythingsimilar to what you mention. Go, my son, and tranquillize yourself; be assured that whatyou take for spots in the sun are the faults of your glasses or your eyes.” The inflexibleprovincial would not allow him to publish his observations and opinions under his ownname. He only consented to an anonymous publication of them, as mentioned in thetext.

f Discorso intorno alle Cose che stanno in su l’Acqua. Firenze , 1612.

’ Istoria et Dimostrazioni intorno alle Macchie Solari et loro accidenti dal Signor GalileoGalilei, &c. Roma, 13 gennaro, 1613.

§ M. Arago, in his valuable “ Analysis of the Life and Discoveries of Sir WilliamHerschel, ” published in the Annuaire for 1842, has discussed with great ability the claimsof the various individuals to whom the discovery of the solar spots has been attributed.He rightly refuses to Galileo the credit of having discovered the spots eighteen monthsprevious to his first letter to Welser, on the ground that the claim to the discovery rests onthe bare assertion of its author. He, however, readily admits that if Galileo ’s letters con-tained the records of any observations made in the preceding year, such records should beconsidered as fully substantiating his claim to the discovery. The following are thewords of M. Arago in reference to this point:—“ Le meilleur moyen de trancher toutedifficulty sur la date de la decouverte des taches eut ete de rapporter de veritables obser-