284 British Association for the Advancement of Science. | 
mean R. A. and North Polar distance of the object for the begin- 
ning of 1830, together with a description, in abbreviated language, 
of its appearance and physical peculiarities, as to size, brightness, 
condensation, é&c. The observations of double stars in the pneasy 
catalogue, express the mean place for the epoch above named,— 
the angle of position of thestars with the meridian, as micromet- 
rically measured. at the time of observation,—the estimated dis- 
tance, and the magnitude assigned to each star, with a column 
of remarks, in which are noted peculiarities of color, &c. 3. Mi- 
crometrical Measures of 407 principal Double Stars of the South- 
ern Hemisphere, made at the Cape of Good Hope. with a 7- ~feet 
Achromatic Equatorial Telescope. 'These measures were taken 
with the same achromatic and micrometer, and are arranged in pre- 
cisely the same’ manner as the former similar observations made 
by Sir J., and printed in the Trans. of Royal Astron. Society. 
_ Among the principal double stars in this paper occur, « Centauri, 
« Crucis, 7 Centauri, 7 Lupi, « Lupi, « Lupi, ¢ Hydre, « Chamele- 
ontis, 7 Piscis volantis, 7 Corone Australis, ‘&c. These measures 
afford unequivocal evidence of. rotation in.some of these double 
stars, particularly in « Centauri, @ Hydre, y Corone, and 7 Lupi. 
In « Centauri, the decrease of distance, even within the short pe- 
riod of observation, is remarkable ; and Sir J. remarked, that on 
examining the eatalogues of the Astron. Soec., and that of Capt. 
Johnston, and the Paramatta Catalogue, in all which, the places 
of the two stars are given separately, he finds this diminution of 
distance fully borne out and regularly progressive; from which 
he concludes that in 15 or 20 years from this time, the stars may 
be expected to appear in contact, or to be actually occulted one 
by the other, as has recently been observed to happen toy Vir- 
ginis. 4. A list of the Approximate Places of 15 Planetary and 
Annular Nebule of the Southern Hemisphere, discovered with 
the 20-feet Reflector ; with Drawings illustrative of the Appear- 
ance and structure of 3 principal Nebule in the Southern Hem- 
isphere. These are-arranged in order of R.A.-and numbered. 
Among these, several are somewhat elongated, and offer the ap- 
pearance of being double. No. 7 is of a fine blue color, and 
_ being particularly well-defined, has exactly the aspect of a blue 
planet. No. 4 is a very bright and considerably large elliptic 
dise of uniform light, on which, but excentric, is placed a — 
large star. Several are very small; No. 15 is not more than 3” — 
“3 ageeee 
