lii S 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 Northern 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 
Royal 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 nebule 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 
