DISCOVEKIES IN THE CELESTIAL SPACES. 703 



who had proposed to give to 'Jupiter's satellites the name 

 of Sidera Brandenburgica ; whilst Galileo preferred the names 

 Sidera Cosmica or Medicea, of which the latter found most 

 approval at the court of Florence. This collective appel- 

 lation did not satisfy the yearnings of flattery. Instead of 

 designating the satellites by numbers, as we do at present, 

 Marius had named them lo, Europa, Ganymede, and Cal- 

 listo ; but for these mythological designations Galileo's no- 

 menclature substituted the family names of the ruling house 

 of Medici, Catherina, Maria, Cosimo the elder, and Cosimo 

 the younger. 



appear that he attempted somewhat unphilosophically, to direct his com- 

 plaint against Marius to the Marchese di Brandeburgo. On the whole, 

 however, Galileo continued well-disposed towards the German astrono- 

 mers. He writes, in March, 1611, " Gli ingegnisingolari, che in gran nu- 

 mero fioriscono nell' Alemagna, mi hanno lungo tempo tenuto in desiderio 

 di vederla" (Opere, t. ii. p. 44). It has always appeared very remarkable 

 to me, that if Kepler in a conversation with Marius, was playfully 

 adduced as a sponsor for these mythological designations of lo and 

 Callisto, there should be no mention of his countryman, either in the 

 Commentary published in Prague, in April, 1610, to the Nuncius Side- 

 rius, nuper ad mortales a Galilceo missus, or in his letters to Galileo, or 

 in those addressed to the Emperor Rudolph in the autumn of the same 

 year; but that on the contrary Kepler should everywhere speak of "the 

 glorious discovery of the Medicean stars by Galileo." In publishing 

 his own observations on the satellites, from the 4th to the 9th of Septem- 

 ber, 1610, he gives to a little memoir which appeared at Frankfort in 

 1611, the title, " Kepleri Narratio de observatis a se quatuor Jovis 

 satellitibus erronibus quos Galilceus Mathematicus Florentinus jure in- 

 ventionis Medicea Sidera nuncupavit." A letter from Prague, October 

 25, 1610, addressed to Galileo, concludes with the words "neminem 

 habes, quern metuas amulum." Compare Venturi, P. 1. pp. 100, 117, 

 139, 144, and 149. Misled by a mistake, and after a very careless 

 examination of the valuable manuscripts preserved at Petworth, the 

 seat of Lord Egremont, Baron von Zach asserted that the distinguished 

 astronomer and Virginian traveller, Thomas Harriot, had discovered 

 the satellites of Jupiter simultaneously with, or even earlier than 

 Galileo. A more careful examination of Harriot's manuscripts, by 

 Rigaud, has shown that his observations began, not on the 16th of 

 January, but only on the 17th of October, 1610, nine months after 

 Galileo and Marius. (Compare Zach, Corr. Astron., vol. vii. p. 105. 

 Rigaud, Account of Harriot's Astron. Papers, Oxf., 1833, p. 37* 

 Brewster, Martyrs of Science, 1846, p. 32.) The earliest original obser- 

 vations of Jupiter's satellites made by Galileo and his pupil Renieri, 

 were only discovered two years ago. 



