18 EIGHTH REPORT 1838. 



object for the beginning of 1830, together with a description (in ab- 

 breviated language), more or less detailed, of its appearance and phy- 

 sical peculiarities — as to size, degree of brightness, condensation, &c. 

 The observations of double stars in the second catalogue express the 

 mean place for the epoch above named — the angle of position of the 

 stars witli the meridian, as micrometrically measured at the time of 

 observation — the estimated distance, and the magnitude assigned to 

 each star, together with a column of remarks, in which peculiai'ities of 

 colour or other phenomena are noted. The micrometrical measures in 

 the third paper were taken with the same achromatic and micrometer, 

 and are arranged in precisely the same manner as the former similar 

 observations made by the author, which have been printed in the Trans- 

 actions of the Astronomical Society. Among the principal double 

 stars in this work occur, a Centauri, a Crucis, y Centauri, y Lupi, 

 fi Lupi, TT Lupi, /3 Hydrse, e Chameleontis, y Piscis Volantis, y Coronas 

 Australis, &c. Of these, the measures therein stated afford unequi- 

 vocal evidence of rotation in several of the double stars, among which 

 may be particularized o Centauri, /3 Hydrse, y Coronas, and tt Lupi. 

 In the case of a Centauri, the diminution of distance, even within the 

 comparatively short period of observation, is remarkable ; and the 

 author stated verbally, that on examining the catalogue of the Astro- 

 nomical Society, that of Captain Johnson, and the Paramatta Cata- 

 logue, in all which the places of the two stars are given separately, 

 he finds this diminution of distance fully borne out, and regularly pro- 

 gressive ; from which he is led to conclude, that in no great nimiber 

 of years from the present time (fifteen or twenty), the stars may be 

 expected to appear in contact, or to be actually occulted one by the 

 other, as has recently been obsei-ved to happen to y Virginis. The 

 fourth of these communications is a list of the planetary and annular 

 nebulae of the Southern Hemisphere, which have been detected by Sir 

 J. Herschel in his sweeps. They are arranged in order of R.A., and 

 numbered. Among these, several are somewhat elongated, and ofier 

 the appearance of being double. One of them (No. 7) is of a fine 

 blue colour, and being particularly well defined, has exactly the aspect 

 of a blue planet. No. 4 is a very bright and considerably large elliptic 

 disc of uniform light, on which, but excentric, is placed a pretty large 

 star. Several are very small; No. 15, in particular, is not more than 

 3" or 4" in diameter. Many of them occur in crowded parts of the 

 Milky Way, with not fewer than 80 or 100 stars in the field of view at 

 the same time. — The drawings above mentioned were copies of much 

 more elaborate originals, and were produced merely as specimens se- 

 lected from a greater collection, illustrative of three of the most singu- 

 larly constituted nebulae in the Southern Hemisphere, viz. 6 Orionis, 

 r/ Argus, and 30 Doradus. Sir John Herschel gave several examples 

 from the voluminous tables of the manner of registering the observa- 

 tions respecting each star, double star, clusters, and nebulae ; he also 

 explained how, by the contrivance of a small achromatic collimator 

 placed inside of his great sweeping telescope, he was able to obtain 

 nearly the same precision in his observations as was to be had in fixed 



