172 SPECIAL RESULTS IN THE URANOLOGICAL PORTION 



linking together phenomena whose immediate causes are 

 still veiled in obscurity. For this reason we willingly dis- 

 tinguish between newly appeared stars which have again 

 entirely disappeared (as the star in Cassiopeia in 1572) ; 

 newly appeared stars which have not disappeared again 

 (as the star in Cygnus, 1600) ; variable stars whose periods 

 have been investigated (as Mira Ceti, Algol, &c.) ; and 

 stars whose luminous intensity varies without our having as 

 yet discovered any periodicity in the variation, (as r\ Argus) . 

 It is not at all improbable, but it also by no means necessarily 

 follows, that these four kinds of phenomena ( 281 ) arise from 

 similar causes belonging to the photospheres of those dis- 

 tant suns, or to the nature of their surfaces. 



As we began the description of the new stars with the 

 most remarkable instance of this class of celestial events, i. e. 

 the sudden appearance of the star of TychoBrahe, so, guided 

 by the same reasons, we will begin the description of the 

 alteration of the light of stars, in which the periodicity of the 

 variation has not yet been investigated, by the still proceeding 

 unperiodic fluctuations of luminous intensity in the star 

 q Argus. This star is situated in the great and magnificent 

 constellation of the Ship, which is the " glory of the southern 

 heavens/' As early as ] 677, Halley, on his return from his 

 voyage to St. Helena, expressed many doubts respecting 

 change of light in the stars of the Ship Argo, particularly 

 on the shield of the prow and on the deck (aainSioK.?! and 

 icard<rrpwjua), whose relative order of magnitude had been 

 given by Ptolemy ( 282 ) ; but from the uncertainty of the star 

 positions of the Ancients, the many variations in the manu- 

 scripts of the Almagest, and the uncertain estimations of 

 luminous intensity, these doubts could not lead to any results. 



