Hi Appendix. 



constellation Musea. It passes through all its changes in the extraordinarily 

 short period of twenty-one hours and fifteen minutes, and during one-fifth of 

 that time is invisible to the unassisted eye. The other is in the Southern 

 Triangle, and has a period of three and a half days, during part of which time 

 it also is invisible. Professor Gould, in his inaugural address, calls attention 

 to the great field that lies before the southern observer of the fixed stars. 

 The number of stars belonging to the T^orthern Hemisphere whose positions 

 and magnitude have been catalogued is 330,000, whilst less than a sixth of 

 that number have been defined in the regions south of the equator. Of the 

 latter by far the greater number are stars which are visible in Europe. A 

 circle drawn round the South Pole, with a radius of 60° of latitude, will 

 only include 13,000 known stars, whilst a similar tract of the northern sky 

 includes 164,000. Great as is the difference between the two regions in 

 brilliancy, it is certain that much work has to be done before the catalogues of 

 southern stars reach anything like the perfection of those of the north. 



The Cordoba observers have been watching the variabilities of stars. Far 



vaster changes in celestial objects have been subjects of investigation to other 



astronomers in this hemisphere. It is now some years since Mr. Abbott, of 



Hobart Town, pointed out the fact that the star eta Argus is no longer 



actually in the nebula where it was seen by Sir John Herschel. The careful 



observations of the nebula and neighbouring stars which have been incited by 



this discovery, have led to the knowledge of extraordinary changes now in 



progress in this distant object. The Melbourne observers have paid great 



attention to the subject, and Mr. M 'George, in a paper read a few months ago 



before the Royal Society of Victoria, gave a sketch of the results, illustrated 



by five drawings of the nebula, as observed at different times. The changes 



which have occurred since the great Melbourne reflector was first turned towards 



it have been rapid and most extraordinary. It is much to be regretted that the 



Hoyal Society of Victoria is not in a position to publish the more important of 



the papers read at its meetings, some of which are of world-wide interest. Now 



that the Melbourne Observatory possesses one of the finest telescopes in the 



-world, we may expect that from year to year the indefatigable and able men 



who have the charge of it will be in a position to add greatly to our knowledge 



of the phenomena of the southern heavens. The attention they are paying to 



this and other nebulae will no doubt lead to an increase of our knowledge of 



the physical constitution of these wonderful objects. For instance, when eta 



Argus was first observed to have broken loose from the dense nebula in which 



it was seen by Herschel, the lines of burning hydrogen were distinctly seen by 



Mr. Le Sueur in its spectrum. He then offered the conjecture that the star 



had consumed the nebula. In the latest observations of which I have seen 



any account no trace of the bright hydrogen lines was found, but the star was 



