THE COLOUEED STAES ABOUT KAPPA CETTCIS. 93 



And the mean magnitude of Herschel's 110 is 13, while tlie mean 

 of my 130, including of course the new stars, which are all small, 

 is 12. 



I have been thus particular in detailing the history and recent 

 observations of this object, because some important consequences 

 flow from the results, and very much has been lost or left un- 

 certain, simply because early observers were not particular. 



The wonderful accuracy of Sir John Herschel's work forbids 

 us from regarding in any other light than as facts the startling 

 changes which I have just recorded ; facts which prove, I think, 

 beyond all question, that from some cause there has here, as in 

 Eta Argus nebula, been a considerable increase in brilliancy. 



What may be the cause or causes of these changes it is very 

 dif&cult to say, but the position of the object is remarkable. 

 Situated between Beta Crucis and the Coal Sack, or rather right . 

 on the edge of that strange, dark place, still a puzzle to 

 astronomers, who know not whether it is a want of stars, a hole 

 so to speak ia the galactic circle, or whether it is a cosmical 

 cloud, shutting oiit the light of many stars beyond it — though on 

 careful examination it has to me the latter appearance, the few 

 stars that are seen being not clear, definite points on a dark sky, 

 but hazy specks, as if seen through a fog — but whether it be the 

 one or the other, it is exceedingly probable that any change in 

 the position from which objects on its border are seen would alter 

 their appearance, either to bring them into a clearer or thicker 

 place. 



Now, we know that the sun, and with it of course the earth, is 

 moving mth enormous velocity in space, probably round some 

 point not yet determined, but with a present direction towards 

 the constellation Hercules, a direction which is nearly at right 

 angles with the visual line to Kappa Crucis ; so that, having been 

 changing our place at the rate of one hundred and fifty millions 

 of miles per annum for thirty-six years, we may have altered the 

 visual line sufB.ciently to account for these changes, more especi- 

 ally as the rather large proper motion of the cluster is carrying 

 it as it were into the dark space ; but whatever theory we may 

 adopt to arrange the few facts which have been collected bearing 

 ■ on the constitution of the starry firmament, it is very diflB.cult on 

 either to account for the apparition of these stars. If we take 

 the view pubhshed in 1750, by Thomas "Wright, in his theory of 

 the universe, that the stars are probably of the same size, and 

 arranged according to some general plan, and therefore their 

 distance regulates their apparent size, it is not easy to see how 

 minute stars such as these could become visible by any change 

 which can in so short a time have taken place in their distance 

 from us, more especially since, so far as we do know, that distance 

 has increased, and would of course prqduce an opposite effect. 



