ORBITS OF DOUBLE STARS 



mathematicians. It ia twice aa heavy aa our 

 Htm, l.ut doea not give a fiftieth part of the light 

 Stars then may be double, or treble, or even quadi 



iture. or by the accident of position. 

 Compai own observations and auch othem aa 



lie could procure, Herachel calculated that the one star 

 moved round the other, or that both moved round their 

 common centre of gravity in th<> following double 

 Can: 



Outor in about 348 yean 2 month*, 

 y Laoois in about 1800 year*. 

 Bootis in not leei than 1681 year*, 

 3 ScrpetttU in about 375 year*. 

 y Virginia in about 706 year*. 1 



Another double star that he carefully examined waa 



Uerculis, It presented him with a sight "v. 

 ia new in astronomy; it ia, tli. occultation of one star 

 Km- twenty -one years he continued to 

 keep a watch on the star. After twenty years had 

 passed he could no longer perceive the smaller of the 

 two companions. llowing year he f<mn<l 'the 



apparent disk a little distorted; but there could not 

 be more than about } of the apparent diameter of 

 the small star wanting to a complete occultat 



the observations made were not sufficient to 



determine the nature of the motion that produced 



[these effects. The long period of 1681 years set down 



against i Bootis, Herschel himself points out as subject 



vruintieH, which it will take long to clear up. 



1 ' One thing rery remarkable I tnott tell TOO, y Virginia U now o 

 *?/< Jter in both the twenty-foot, and the eeren foot equatorial 

 (Sir John Henche), March 8, 1886). He means that one of the two 

 mu had eclipecd the other. 



