Double Stars. 55 



star, which, though not a brilliant object, takes the first rank in 

 a dnll neighbourhood. This is Al Rdi, alias Ras-al-hangue, in 

 the head of the large though inconspicuous constellation 

 Opliiuclms, whose legs reach below the serpent which he is 

 carrying, a long way towards the S. horizon. A few degrees 

 W. and slightly N. of this star, is a much smaller one, Ras-al- 

 Gjdthi, marking the head of Hercules, another widely extended 

 constellation in an unaccountably undignified posture, kneeling 

 on one knee with his feet uppermost. The heads of these two 

 singular figures thus awkwardly "laid together" for thousands 

 of years, ought to be familiar to the student as guides in a 

 neighbourhood barren to the eye, but full of telescopic interest ; 

 the head of Hercules itself giving us a grand object; — 



24. a Eerculis. Ras-al Ojdthi.. 4**5. 118°*7. 3f and 

 5|. Orange and emerald or bluish-green ; intense ccerulea, 

 according to Struve. Sir W. Herschel considered that the 

 principal star was variable from 8 to 4 mag. in 60? days : 

 Struve has not confirmed it, but has seen the companion some- 

 times 5, at others 7 mag. Argelander, who doubts this, fixes 

 the period of the large star at 66*4 days ; Baxendell at 88*5 

 days. This "lovely object," as Smyth calls it, "one of the 

 finest in the heavens," though looking so much like a system, 

 has not as yet been proved to be in motion. A power of 80 

 will draw it out and show its colours in a good glass, though of 

 course it will gain in beauty by magnifying. 



25. 8 Herculis. 25"*9. 173°*9 (1830-71). 24"*5. 175°*1 

 (1839*62). 4 and 8£. Greenish white and grape-red. Struve 

 daring 7 years marked the companion " albacinerea." I 

 thought it bluish-green in 1850. Fletcher made them yellow 

 and red, 1851*67; Dembowski, yellow and blue, 1854, 1855; 

 white and blue, 1855, 1856. This is probably a binary system, 

 and if so, is a fair instance of a very remarkable fact, which, 

 however, does not depend upon such slender proof as this 

 single example, but is evident in other cases and ways, that 

 the brightness of stars is, at least in many cases, no indication of 

 their real distance. Here we have an 8|- mag. star in all pro- 

 bability as near to us as its very much larger companion. This 

 conclusion once admitted — and how it can be resisted, it is diffi- 

 cult to see — very remarkable consequences follow ; speculations, 

 however ingenious and beautiful, which assume anything like a 

 general distribution of stars throughout space according to 

 apparent magnitude, fall away of themselves ; and but for the 

 modern improvement in instruments, which renders the deter- 

 mination of parallax no longer impossible, we should be left in 

 entire uncertainty as to the real marshalling of the starry host ; 

 and even that " longior scala astronomorum," as Kepler calls 

 it, while it confirms the overthrow of all arrangements based 



