15 



been under his notice. We may evidently expect at some future time to 

 hear of still more interesting discoveries in this department of sidereal 

 astronomy." 



The Heavens, Imperial Observatory, Paris. — " We will bring this 

 chapter to a close with a description of the most astonishing of all the 

 phenomena of this kind, — namely, the variations of the star t] Argus ; a 

 singular star, which can be classed neither among the temporary nor 

 among the variable stars. Towards the end of the seventeenth century 

 this star was only of the ith magnitude ; less than a century after, in 1751, 

 it attained the 2nd. Sixty years later it again descended to its first 

 brightness, increasing anew until the year 1826. From that epoch it has 

 passed through the most astonishing phases, oscillating between the first 

 and second magnitudes, sometimes equal to a Crucis, then to a Centauri, 

 surpassing Canopus, and approaching lastly to Sirius. The rapidity of 

 these changes, their unequal periods, the long duration of this state of 

 variability, the impossibility of finding a law more or less regular, all con- 

 tribute to make this beautiful star one of the most curious objects of the 

 sky. Our cotemporary astronomer, Mr. F. Abbott, who has followed the 

 variation of tj Argus until now, informs us that after having, in 1843, 

 attained the brilliancy of Sirius, it diminished progressively, passing 

 through all the orders of intermediate magnitude between the first and 

 sixth. In 1863 it was no longer visible to the naked eye. We are also 

 informed that the nebulosity which surrounds rj Argus, like that of Orion, 

 does not present any symmetry in its form or in its outline. It is situated 

 in the Milky Way, in the midst of a region so rich in stars, that more 

 than 1,200 have been counted in the area occupied by the nebula. The 

 stars, however, do not form part of the nebulosity, but rather appear to 

 be simply projected on it. Towards the centre of the nebula, and close to 

 the star t), an opening of a lengthened and rounded form is noticed, which 

 leaves in view the dark ground of the sky. This has been named by Mr. 

 Abbott, a careful observer, ' the Crooked Billet.' The evidences of change 

 in this nebula are even more decided than in that of Orion. This object 

 indeed may supply a link of the greatest importance, for we read that the 

 objects of which it is compose'! ^not stars) ' are now of a larger character 

 and more refulgent than nebulous matter in general.' " 



I may mention here that this object is not seen at all in 

 Europe, at the Cape of Good Hope and Madras it is only 

 partia-lly seen, as in one part of its revolution it dips below 

 the horizon. The only other object of a known similar 

 nature in the heavens at the present time is the great nebula 

 in Orion, which for some years past has been rigidly 

 examined with the most powerful instruments, and discussed 

 by the best observers with a view of investigating some 

 apparent fluctuations. What follows will show that those 

 changes, although now established, bear but a feeble com- 

 parison to V Argus and its nebula — the latter, however,will help 

 to confirm what has been long suspected of the former. A 

 paper on the nebula of Orion, read by the late Earl of Rosse 

 before the Eoyal Society of London at the close of their last 

 session, clearly shows that in the course of the last fifteen 

 years considerable changes have taken place in that object — 

 changes which cannot be attributed either to atmospheric 

 difficulties of vision, or to alterations in the instruments, or in 



