For the years 1868-1874 an additional correction, due to wear of the micrometer screws, is required, for particulars of which reference can be made to the Nine-Year Catalogue, 1872, in the introduction to which catalogue will be found a full and complete explanation. The results of the Greenwich observations thus corrected and reduced to one homogeneous system, when compared with the observations which Mr. Chandler has gathered together from all parts of the world, show a wonderful similarity of contour and general agreement in detail, the more remarkable when it is considered that many of the observations so collected by Mr. Chandler were made for special purposes with special instruments, with a special view to a discussion of this character. The agreement between all the curves is so good that the deviations become all the more accentuated, and, as Mr. Chandler remarks, in speculations on this subject it seems desirable to hold to a prudent reserve for further investigation. Incidentally to this investigation several other important questions have arisen, which are still under discussion.

Nova Auriga. By Isaac Roberts, D.Sc., F.R.S.

A photograph of the region of Nova Aurige was taken on October 3, 1892, with the 20-inch reflector, and exposure of II0 minutes, upon which the Nova appears as a star, as well defined as any of the other stars, which are very numerous, on the plate. There is no trace of nebulosity surrounding the Nova, or in its vicinity, and there is no feature about it suggestive that it is different from other stars. The diameter of its photo-image measures 21 seconds of arc, and about 85 seconds distant from it, on the n.f. side, is a star the photo-image of which measures 23 secs. of arc; the Nova is therefore 2 seconds in diameter less than the star.

On December 25, 1892, another photograph was taken of the same region, with an exposure of 20 minutes, upon which the Nova has a photo-image of 13 seconds of arc in diameter, and the star referred to has a diameter of 16 seconds. If we proportion the measured diameters obtained on the days stated, we shall have the following:

23:16::21: 14′′63, the diameter of Nova.

But the diameter of the Nova measures only 13 seconds, which shows a decrease of 1"63 in diameter between October 3 and December 25.

There is no indication of nebulosity round the Nova, or in its vicinity, on the December plate, and it appears as sharply defined as the other stars.

So far, therefore, as the evidence obtained by the eleven

photographs which I have taken between the date of the appearance of the Nova and December 25, there is nothing upon them indicative of a disturbance, such as we might expect to see recorded if a body of the magnitude and velocity of the Nova had rushed into a nebula, or into a swarm of meteors. On the other hand, it might be argued that the great velocity of the star would carry it through without causing such great disturbance at right angles to the line of flight, according to dynamic law, that a projectile at a high velocity will penetrate through a plate of iron, or of glass, without fracturing them in the manner that a projectile would at a low velocity. On this hypothesis the inrush of the nebulous or meteoric matter, to fill the vacuum created by the star, might account for the peculiar spectra which were observed.

Photograph of the Nebula III. 55 Pegasi. By Isaac Roberts, D.Sc., F.R.S.

The photograph of this nebula, now presented, was taken with the 20-inch reflector on 1892 October 22, and exposure of 4 hours. The scale is 30 seconds of arc to one millimetre. R.A. 23h om; Decl. N. 11°45', at the centre.

The nebula is No. 4892 in the General Catalogue, and is described as pretty bright, considerably large, much elongated towards 12° between two stars, irregularly round, two or three stars in it, pretty generally much brighter in the middle. It is figured in the Phil. Trans., 1833, pl. 14, as a faint ray, with a faint star near each extremity.

Lord Rosse, in his "Observations of Nebula and Clusters,' p. 170, describes the appearance of the nebula, and it is figured in the Phil. Trans. for 1850, pl. 36, fig. 4. The drawing shows a bright broad boundary on the following side, and on the preceding side of it a circle filled with spiral convolutions, strongly marked. A star is shown in the centre of the convolutions, but later observations, made between the years 1849 and 1876, do not with certainty confirm the spiral structure.

The photograph shows the nebula to be a faint ellipse, with a dense broad line, curved at both ends, forming the major axis. There is a star of about 15th magnitude in the centre of the axis, and there is also a fainter star in the preceding semi-ellipse, but there is no structure visible within it, such as that shown on the drawing by Lord Rosse, and it does not show the semiellipse on the following side, which is faintly visible on the photograph. The object is altogether a difficult one, either to see or to photograph.

Photograph of the Cluster H VI. 30 Cassiopeice.
By Isaac Roberts, D.Sc., F.R.S.

The photograph now presented was taken with the 20-inch reflector on 1892 November 26. Exposure 90 minutes. Scale 30 seconds of arc to one millimetre. R.A. 23h 52m; Decl. N. 56° 8', at the centre.

The following description is given by Sir John Herschel in the Phil. Trans. for 1833, p. 480 :-"A. most superb cluster which fills the field and is full of stars; generally brighter in the middle but no condensation to a nucleus. Stars 11th to 18th magnitude.

Lord Rosse, in his "Observations of Nebulæ and Clusters of Stars," p. 177, describes the cluster as very coarse; stars quite distinct and no visible nebulosity; dark holes and jagged branches, but no regular arrangement.

The photograph shows the cluster to be in fair accord with the descriptions given by Herschel and Rosse as far as they apply; but in addition it shows patterns, consisting of lines, wreaths, and curves of stars, which on the negative are very prominent features. The photograph confirms the eye observations, that there is no nebulosity in the cluster, and, since it shows every star in its true relative position and magnitude, down to about the 16th, the further evolution of this cluster may henceforth be strictly followed by us and by our successors,

The Eclipse of the Moon, 1892 November 4-5.

Sydney Observatory.

Observed at

(Communicated by H. C. Russell, B.A., F.R.S., Government Astronomer.)

At

The weather was most unpromising for observation, owing to the ever-changing and too abundant clouds; however, at 11h 45m through a break in the clouds, a slight shade, the effect of the penumbra, was visible on the eastern limb of the Moon, and the first contact with the shadow was seen at 12h 14m 20s. 12h 17m the first photograph was taken, and a few minutes later an extensive cirrus-cloud covered the Moon, and a large halo was visible for a time. The cloud continued to increase, and interfered very much with observation. There was no sign of coppery colour, the shadow being so dark-a very dark brown, almost black-that it entirely blotted out the Moon's limb and markings on the surface, which are usually seen through it on such occasions. At 12h 43m a partial break in the cloud gave opportunity for another photograph, exposed 308. At 12h 53m the Moon was half eclipsed and the clouds had become thicker, so much so that no features of the Moon were visible through the shadow or eclipsed part of the Moon. At 12h 55m another photograph was taken, and the exposure was increased to 1m.

At 1h 28m A.M. the eclipse was announced to become total, but here the Moon did not become wholly involved in the shadow.* The white strip of Moon visible at the total eclipse travelled round the northern limb of the Moon as the eclipse proceeded.

At 2 A.M. clouds cleared a little, and it could be seen by its coppery tint that the Moon was passing gradually out of the very dark part of the Earth's shadow-cone into a lighter part, in which the usual coppery-red light was bright enough to illuminate the Moon. On the northern side of the Moon, and extending upwards, the red or coppery colour seemed to involve three-fourths of the Moon, and a few minutes later-2h 10m the Moon had passed altogether out of the dark shadow, and the whole of it was visible in red light. At 2h 12m, the end of total eclipse, the white patch already referred to was on the N.E. side, and the colours on the Moon were unusually beautiful. A minute white crescent on the N.E. was fringed by greenish-grey light, which seemed to extend the crescent half round the Moon and hold in its grasp a brilliant coppery-red ball, the whole Moon, of which the lightest red was next the greenish-grey crescent, presenting altogether the most beautiful view of an eclipsed Moon that I have ever seen. At 2h 30m A.M. clouds again covered the Moon until six minutes past 3 A.M. At 3h 8m A.M. another photograph was taken. The coppery colour had gone, and the shadow on the Moon looked nearly as black as it did at the beginning of the eclipse. At 3h 24m A.M. another photo was taken. The last contact was observed 3h 26m A.M., and the penumbra still cast a faint shadow over part of the Moon, and three minutes later clouds again claimed possession. Six successful photographs of the Moon were obtained.

Observatory, Sydney N.S.W.: 1892 November 5.

Estimations of Magnitude of Nova Auriga, made at the Radcliffe Observatory, Oxford. By E. J. Stone, M.A., F.R.S., Radcliffe Observer.

Estimations of the magnitude of the Nova have been made on the following nights: 1892 November 18, 26; December 9, 12, 22, 23; and 1893 January 2 and 10. The mean magnitude given by these observations is 9'7, and it would appear that no sensible changes of magnitude have taken place during the interval over which these observations extend.

Radcliffe Observatory :

1893 January 12.

[* The Superintendent of the N. 4. kindly informs us that "the Moon's centre was north of the shadow's centre, so that the Moon's north limb was close to the edge of the shadow, and small errors in adopted values might make it visible. The diameter of the shadow is increased in a certain proportion for one thing, but this assumed enlargement probably varies with the atmospheric conditions at the time of each eclipse.”—SECRETARIES.]