the general brightness. The two streams which formed the tail were for a long time unequal in breadth, but were never observed to change sides so as to indicate rotation: the antecedent branch showed greater fulness and density near its origin even with the small object-glass on Sept. 24. With the large one, on Sept. 30, it was estimated the broader in the ratio of about 4 to 3; on Oct. 4 and 5, as 3 to 2. Oct. 11, they appeared with the small telescope of equal breadth. During the whole time the angle at which they came off from the nucleus underwent a steady increase: the antecedent stream was always far better defined than the other at its exterior edge. These two streams were connected round the sunny side of the envelope or photosphere, by a border of the same material, much narrower and fainter than the envelope. This border, which formed the vertex of the tail considered as a paraboloid, was, on Oct. 4 and 5, suspected to be bounded by a delicately brightened up semicircular edging, as though it were merely a thin shell; but this remained questionable. Beyond this border a considerable extent of very faint haze was visible, melting gradually into the clear sky. During the magnificent transit over Arcturus it was remarkable how distinctly and fully the light of the large object-glass brought out the tail, even close to the dazzling disk of that vivid star.

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To the naked eye there was a remarkable irregularity in the curve of the tail, which gave strongly the impression of the exhaustion, beyond a certain distance of the projectile or repulsive force, and of a consequent diffusion and dispersion of the luminous material. This was first noticed on the evening of the transit, when the train extended in a regular curve as far as and Boötis, which were near its centre, but about one-third of the distance between ę and where the tail attained its greatest width, the convexity began to be a little deflected backwards or flattened off. Oct. 8, this was still more conspicuous; the curve of the antecedent side, which was carried regularly up to a Corona, being subsequently deflected from the direction of d Draconis, to which it had previously tended, towards a fresh point between and Draconis, about onethird of their distance from the latter star, as far as could be ascertained in making an estimate of so very dim an object; sometimes I thought that Draconis was the point indicated. The fainter branch could not be well made out higher than Boötis; beyond this star it seemed, if anything, to approximate again towards the other branch; and the general impression of this side of the tail was that of spreading out like a feather, as compared with the more definite aspect of the convex edge. The whole length on this evening could not have been less than 45°; the greatest breadth, as measured by a Corona and Boötis, about 7°. Oct. 10, the curvature appeared regular as far as a line joining a Corona and Herculis, or perhaps a little further: thence a fainter ray of considerable

as I could judge in the use of an excellent little 24-inch objectglass by Bardon, I think its distinctness on Oct. 11 had increased, as compared with its aspect on Sept. 21. Its colour was a clear yellow, not as deep as that of Arcturus.

2. The Envelope. This was of considerable extent, much fainter than the nucleus, but brighter than the exterior haze and train. Instead of being a hemispherical cap, serving as a base to the tail, as in the comet of 1811, its outline was distinctly continued through an arc of much more than 180°, round to the edges of the central darkness of the train. Sept. 30, when I perceived it on the first trial of the 5-inch object-glass, the portion next the sun was least luminous, and seemed to consist chiefly of a narrow are of light, indicating a hollow structure; this bright ring became more evident at a greater distance from the sun, so that the portions adjoining the central darkness were most conspicuous, especially, perhaps, that on the preceding side, according to the comet's orbital motion. Oct. 4, the whole circumference of the envelope, or photosphere, as it might in this case be termed, appeared entirely filled up with light, excepting where the central darkness cut out a large gap in it. Oct. 5, it was doubtful whether or not its outline was defined by a more luminous arc; but now its principal brightness was confined to about a hemisphere, not however symmetrically situated with respect to the general figure of the comet, but inclining a little backwards as though left behind in its movement, so that the faint sector which completed its form round to the central darkness on the antecedent side was considerably larger than the corresponding one in the subsequent direction: this was not very distinctly made out, but such was the prevailing impression. Oct. 11, when the comet had advanced beyond the range of the great telescope, the smaller one showed, though of course less evidently, a similar appearance; but the more luminous hemisphere now seemed to be inclined the other way, or partially to precede the nucleus in its course, its central radius making an angle of about 30° with the axis of the tail, as though there existed a kind of swinging motion, such as was perceived in the last return of the comet of Halley.

3. The Tail. This gave some intimation of its structure even to the naked eye; in the telescope its central darkness was very conspicuous; and as it advanced in its course the sides of the hollow paraboloid became more thin, and the angle included by them increased. Sept. 30, the proportion of the dusky streak to the whole breadth of the tail was estimated at it occupied perhaps on Oct. 11, while it seemed to have become rather more filled up with nebulous light: the clear and broad notch which it cut out of the photosphere, even up to immediate contact with the back of the nucleus, increasing, of course, in breadth in a similar way. Oct. 4, it was traced for a length of 2° or 220 before it was merged in

the general brightness. The two streams which formed the tail were for a long time unequal in breadth, but were never observed to change sides so as to indicate rotation: the antecedent branch showed greater fulness and density near its origin even with the small object-glass on Sept. 24. With the large one, on Sept. 30, it was estimated the broader in the ratio of about 4 to 3; on Oct. 4 and 5, as 3 to 2. Oct. 11, they appeared with the small telescope of equal breadth. During the whole time the angle at which they came off from the nucleus underwent a steady increase: the antecedent stream was always far better defined than the other at its exterior edge. These two streams were connected round the sunny side of the envelope or photosphere, by a border of the same material, much narrower and fainter than the envelope. This border, which formed the vertex of the tail considered as a paraboloid, was, on Oct. 4 and 5, suspected to be bounded by a delicately brightened up semicircular edging, as though it were merely a thin shell; but this remained questionable. Beyond this border a considerable extent of very faint haze was visible, melting gradually into the clear sky. During the magnificent transit over Arcturus it was remarkable how distinctly and fully the light of the large object-glass brought out the tail, even close to the dazzling disk of that vivid star.

To the naked eye there was a remarkable irregularity in the curve of the tail, which gave strongly the impression of the exhaustion, beyond a certain distance of the projectile or repulsive force, and of a consequent diffusion and dispersion of the luminous material. This was first noticed on the evening of the transit, when the train extended in a regular curve as far as and Boötis, which were near its centre, but about onee-third of the distance between ę and y, where the tail attained its greatest width, the convexity began to be a little deflected backwards or flattened off. Oct. 8, this was still more conspicuous; the curve of the antecedent side, which was carried regularly up to a Corona, being subsequently deflected from the direction of d Draconis, to which it had previously tended, towards a fresh point between and Draconis, about onethird of their distance from the latter star, as far as could be ascertained in making an estimate of so very dim an object; sometimes I thought that Draconis was the point indicated. The fainter branch could not be well made out higher than

Boötis; beyond this star it seemed, if anything, to approximate again towards the other branch; and the general impression of this side of the tail was that of spreading out like a feather, as compared with the more definite aspect of the convex edge. The whole length on this evening could not have been less than 45°; the greatest breadth, as measured by a Corone and Boötis, about 7°. Oct. 10, the curvature appeared regular as far as a line joining a Corone and Herculis, or perhaps a little further: thence a fainter ray of considerable

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breadth was deflected at a large angle, perhaps 60°, as far as the stars of Quadrans Muralis. This portion was very feeble, but certain, and looked quite like a scattered and abandoned vapour. Another observer agreed with me in suspecting that it was less bright at its connexion with the regular tail than a little further off. Oct. 11, the tail has lost all the deflected prolongation, and extends in a simple curve a little above Herculis, perhaps to; its concave part is much scattered, and it has probably a breadth of 8° or 10°.

Unfavourable weather precluded any further observations. The envelope or photosphere, and its interruption by the central darkness, were very clearly distinguished by Mr. With at Hereford, with an excellent object-glass by Bardon, of 32 inches aperture.

Observed at Rose Hill, Oxford, by J. Slatter, Esq.

Absence from home prevented me from making any observations of the comet before its coming to its perihelion.

The observation on Oct. 11 was made with a portable telescope 22 inches aperture, and a power of about 30, the comet being unable to be seen with the fixed telescope owing to trees. All the other observations were made with the 7-foot equatoreal, 5 inches aperture, and power 117.

Oct. 1, 7 P.M. Nucleus not round, irregular oval; perhaps paraboloidal. Larger diam. 12", smaller 9".

Parabolic Envelope distinct and bright, the shape of its posterior boundary not noticed, but in a rough sketch; it descends a little below the nucleus. Measuring through the nucleus, i. e. if parabolic, the parameter 4'1.

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Oct. 5. Unable to find the comet in daylight. As soon as dark it formed a most splendid sight. The tail more curved, like a bright plume, sweeping upwards with Arcturus enveloped near the head, enclosing y Boötis, central at the widest part, and a Boölis just at its boundary, the tip reaching to the triangle formed by 8, 1, x Boötis. This was the fullest size it attained. The nucleus to the naked eye not so bright as on the 1st, which was fully explained by the telescope.

7 P.M. Nucleus small and bright, and round; diameter 4"-8. Envelope very large and bright; the posterior edges greatly prolonged behind the nucleus and opening out at an angle slightly differing from 90° by estimation. Parameter 59".

To the naked eye, Arcturus, through the tail, appeared, if anything, to scintillate more than usual; and in the telescope its light appeared white instead of its usual golden colour.

Oct. 8, 7 P.M. Again to the naked eye a perceptible change, the head having become much brighter since the 5th. The tail also apparently more condensed on the brighter side, and much fainter in its upper part above a Coronæ.

Nucleus much larger, irregular in shape, but not sensibly differing from a parobola. Longer diameter 22" (shorter 11" by estimation).

Envelope very large, the posterior angle much more open; estimated at 150°. Parameter 83". Inside the nucleus was a yet brighter very small nucleus, estimated at z" or 3" diameter; in shape round.

Oct. 9, 6 P.M. Nucleus large, paraboloidal, with a brighter core. Diameter of outer nucleus 31"; inner ditto 9′′.

Envelope had vanished; no trace whatever of any. The tail had greatly diminished in length, not reaching much, if at all, above a Cor. Bor.

Oct. 11, 6 P.M. Nucleus bright; diameter (estimated) 8′′. Envelope. Another now visible, posterior edges open at about an angle of 150°. Parameter 45" about, by measure.

The tail had gradually become more and more curved, and its axis at the head less and less inclined to the earth's equator. The axis of the envelope and nucleus made an angle of 7° or 8°, with the axis of the tail at its origin.

Sextant Observations of the Comet made at Kennington, Surrey, by John C. Haile, Esq.