446 NOTICE OF THE ORBIT OF THE 



zon, though he should not be at the time looking at the heavens, by the increase 

 of general illumination of the atmosphere, resembling the eflfect of the young 

 moon. 



This excessive splendour is caused not only by the profusion of first, second, 

 and third magnitude stars in the neighbourhood, but by the extraordinary general 

 breadth and brightness of the Milky Way thereabouts ; for, separating into so 

 many distinct luminous clouds, as it were, and exhibiting between them void 

 black spaces unchequered by a single luminous object of any kind whatever, 

 it forcibly impresses the idea of our being situated there near the confines of the 

 sidereal system, or in the southern side of the vast ring in which the generality of 

 the stars are arranged. The superior brightness of so large a proportion of the 

 stars is then naturally accounted for by their greater proximity to us ; and this 

 fact was actually proved by my predecessor, who found from his own observations 

 of a Centauri, an annual parallax of the large amount of 1", i.e., that at the dis- 

 tance of this star, the radius of the earth's orbit, or 95 million of miles, subtended 

 an angle of 1" ; the greatest quantity previously found for any star in the Northern 

 hemisphere being only 0-23". 



Professor Henderson's results were fully confirmed by a very much longer 

 series of observations subsequently made at the Cape Observatory by different 

 observers, and with different instruments, and he then computed his old observa- 

 tions of the other principal stars in that region, and finding a considerable num- 

 ber* which shewed also indications of a sensible parallax, he immediately sent 

 out a notice of the results to the present energetic Director of the Cape Observa- 

 tory, for the purpose of procuring from him a greater number of observations of 

 those suspicious stars. Such a series was accordingly commenced, and is still 

 going on, and we may expect before long to hear of trustworthy results having 

 been obtained, and there is little doubt that these labours will still more strongly 

 tend to establish the proximity of that part of the sky. 



On the application of the telescope to a Centauri, it proves to be composed of 

 two stars, one very much brighter than the other, but still both may be placed in 

 the list of first magnitude, the smaller occupying the lowest possible step in that 

 grade. Eai-ly observers have indeed assigned it a much smaller rank, and in the 

 British Association Catalogue published onlj' two years ago, and intending to 

 apply to the year 18.50, it is actually made as low as the fourth magnitude ; this, 

 however, is manifestly an error, for the present epoch, as I can state from the 

 experience derived from making the observations which served to confirm Pro- 



