74 Cincinnati Society of Natural History. 



even in the daytime. It soon began to fail, but remained visible 

 for about sixteen months, when it utterly disappeared to unaided 

 vision. There were no telescopes in those days. 



In 1604 a star shone out with great brilliancy in the constellation 

 Ophiucus. It was called Kepler's star, and was nearly as bright as 

 Jupiter. It continued visible with steadily waning splendor, for 

 upward of two yeirs, when it also disappeard. 



In 1866 a small telescopic star of the ninth mignitude, in the 

 Northern Crown, suddenly shone out with great splendor, becom 

 ing in three or four days as bright as a star of the second magni- 

 tude. Its spectrum was studied by Hug^ins, and exhibited the 

 bright lines of hydrogen, "just as if,'' remarks Prof. Young, " it 

 were a sun like our own, but entirely covered with outbursting 

 prominences of incandescent hydrogen." In the short space of 

 six weeks this star receded to its normal faintness (the ninth magni- 

 tude), and there is nothing in its present appearance to distinguish 

 it from other stars. 



In the year 1885 a star sudden^ appeared in the great nebula ot 

 Andromeda, very near the center of its nucleus. It never reached 

 a greater brightness than the sixth mignitude, and in a few months 

 faded entirely away so that it was not distinguishable from the 

 remainder of the nebula. 



The most conspicuous example of the second class of variables — 

 those having long but irregular periods— is a star in the Whale, 

 known as Mi-ra, or "The Wonderful." It was first seen by Fabri- 

 cius in August, 1596, as a star of the third magnitude, in October 

 of the same year it disappeared. Seven years later, in 1603, 

 Bayer saw a star of the fourth magnitude exactly where that of 

 Fabricius had disappeared, but he did not note the coincidence, 

 and his star faded out in a few months. 



It was not till 1638, nearly forty years after its first discovery by 

 Fabricius, that Holward 1 again identified a bright star of the second 

 magnitude as occupying the precise position of the two preceding 

 stars, and suspected its true character as a variable. During the 

 next two centuries it was studied by Hevelius, Herschel. Argel- 

 ander and others. The telescope has enabled observers to follow 

 it through all its gradations of brilliancy, and it now never entirely 

 disappears from telescopic view. 



Mira has a period of about eleven months. At its minimum 

 and normal brilliancy it is of the twellth magnitude, and remains so 



