ASTRONOMY AND METEOROLOGY. 319 



Mr. Eyre B. Po^rell, an astronomer, resident at Madras, to whom 

 we owe many valuable observations of double stars, and computations 

 of their orbits, states that while engaged in making a series of micro- 

 scopical measures of the stars, in the great nebula surrounding the re- 

 markably variable star ?? Argus (the largest and finest nebula in the 

 southern hemisphere), he was led to notice a most extraordinary 

 change in its configuration. Close adjoining to the bright star Eta (?;) 

 is a very singular oval vacuity, quite devoid of nebula, of a shape 

 somewhat, resembling the figure 8, only with its two compartments 

 communicating ; and having its longer axis nearly in a meridian. 

 According to the elaborate delineation made by Sir John Herschel, 

 during his residence at the Cape of Good Hope, of which an engrav- 

 ing is published in the " Results " of his Cape observations, both ends 

 of this oval were then (1835-1838) completely closed, the southern 

 especially, being bounded by a strongly-marked and definite outline, as 

 if cut out of paper. At present, this oval, we are informed by Mr. 

 Powell, is decidedly open at the south end. The phenomenon, thus 

 stated, is perhaps the most startling thing which has yet occurred in 

 sidereal astronomy, and coupled with the capricious variability of Ar- 

 gus itself, is calculated to open a field for the wildest speculation. 



PARALLAX OF MIXUTE STARS. 



It Avas long and naturally supposed that the most conspicuous fixed 

 stars were also the nearest, and that their brightness was, at least in a 

 general sense, dependent upon their situation with respect to our- 

 selves. It is now capable of demonstration that this is a fallacy. 

 As far back as the year 182G, Sir John Herschel stated that there 

 were " plausible grounds for a belief that, in situations remote from the 

 Milky Way, minuteness, on the average, is not the effect of distance;" 

 and this belief may now be said to have ripened into confidence. It 

 may still be doubtful whether such an assertion may be applicable to 

 the average of stars in any portion of the heavens ; but it is no longer 

 a question whether, in many instances, it may not be capable of direct 

 proof. A fair presumption would arise from the admitted fact, that 

 the proper motions by which many of the stars are steadily changing 

 their positions are by no means always the largest in the brightest in- 

 dividuals ; still, this presumption would not amount to actual demon- 

 stration. This could only be attained in one of two ways : either by 

 showing that great differences of magnitude exist between the compo- 

 nents of binary systems, or by the most direct mode of all that of 

 the detection of an annual parallax ; in other words, an apparent 

 change in the star's place resulting from an actual change in the posi- 

 tion of the observer's eye, as our annual orbit carries us round the sun. 

 It has been for some time known that the parallaxes of several of the 

 brightest stars are, if not absolutely insensible, as Peters found with 

 regard to Cygni, and as Airy has suspected in the case of a Lyrse, 

 yet much smaller than that of 61 Cygni, a star of only the 6th magni- 

 tude, which, according to Sir W. Herschel's estimate, would have been 

 about twelve times more distant ; but it has been reserved to the pres- 

 ent day to carry onward this demonstration to a much greater extent 

 by applying it to stars of a far inferior order. This interesting result 

 has been obtained by means of the excellent helioineter at Bonn, in 



