OF AN EIGHTH SATELLITE OF SATURN. 281 



tian Huyghens, in Holland, who is also entitled to the credit 

 of first ascertaining the true nature of Saturn's ring.* On the 

 25th of March, 1655, while observing the ring of Saturn with a 

 twelve-foot telescope, Huyghens's attention was attracted to the 

 appearance of a star, which, carefully observed at the time and 

 on the following evening, was evidently found to have changed 

 its absolute place in the heavens, and to have shared the retro- 

 grade motion of the planet. These observations were continued 

 every night, and on the "3d of April the new star was found on 

 the other side of the planet. 



The uncertainty, which still hung over many of what are now 

 the most familiar facts in the solar system, led the astrono- 

 mers of this period, instead of hastening with the utmost prompt- 

 ness to give their discoveries to the world, either wholly to sup- 

 press them, for a considerable time, or to communicate the dis- 

 covery to some friend, wrapped up in the form of an anagram. 

 Having repaired to Paris shortly after the discovery of a satel- 

 lite of Saturn, and having there communicated it to his scientific 

 friends, they advised him to make it public, which he did on 

 the 5th of March, 1656, with an hypothesis explaining the other 

 phenomena of Saturn, the latter, however, '^ confuso elementorum 

 quibus scribehatur ordine." In 1659 he thought the time had 

 come for an ampler treatise on the subject, and accordingly pre- 

 pared his Sysiema Saturnium,f where the gradual steps of his dis- 

 covery and his entire system of Saturn are set forth. This inter- 

 esting tract is dedicated to Prince Leopold of Tuscany, and in 



* On the history of the discovery of Saturn's satellites, see Aslronomie par La- 

 lande, III. p. 202, and Smyth's Celestial Cycle, I. p. 197. 



t Chrisliani Hugenii Systema Saturnium, sive de causis mirandorum Saturni 

 Plicenomenon et comite ejus Planeta novo. Hagse-Comitis, 1659. 



