308, 309 Rev. T. W. WEBB: on the Great Comet of 1861. as it is distinctly marked, and prolonged a little beyond it on the lower inverted side. Outside of this vacancy all is diffuse nebulosity, with some doubtful traces of streakiness, as if envelopes still existed there, not separately distinguishable. The orbitally preceding or south side is especially confused and ill made out. July 5. The dark area is nearly obliterated, but the coma exterior to it seems streaky, as though composed of a number of narrow veils. July 8. No envelopes remain. III. The Luminous Sector or Fan.—This, as immediately connected with the nucleus, might have been described before; but, as its formation was at first incomplete, the observations may be more intelligible from its postponement. The first indication of its existence was the very intense light of that portion of the parabolic are, or second envelope, which seemed to issue from the left side of the nucleus. This was very conspicuous in the first observation, and probably continued traceable, with little alteration, to the last. It has been drawn in fig. 1, as represented in the original sketch, coinciding with the external edge of the parabola; but I could not be confident as to this, not having expressly attended to the point; and from subsequent appearances it is more likely that it followed the interior curve of that envelope. It had not been noticed in sketching with the low power of the comet eyepiece, about 27, but was clearly brought out with powers of about 110, 170, 275, and even 460, as a strong curved ray or vivid stream, actually emanating from the material of the nucleus, and gradually losing itself in the envelope. July 2. The sector was more fully developed; in the comet eyepiece it was hardly discernible from the irradiation of the nucleus; but 110 brought it out beautifully, and it was visible even with 460. It extended, as in fig. 7, through about 125°: the upper inverted edge, which was the brightest part, and barely distinguishable from the nucleus at its origin, standing at an angle of about 190°; the other edge, shorter, less defined, and apparently a little curved, at about 315°; a portion of the included area preceding the nucleus was fainter than the rest. The extent of the upper cusp towards the Sun might be 4th of the distance from the nucleus to the indentation in the envelope No. 4. July 3. The sector has a greater angular extent than last night, its edges standing at about 170° and 330°. It is very conspicuous in strong twilight, and has a radiated appearance, which had been suspected, but not verified, last night: the edge directed towards the Sun has lost its vivid light, and the brightest portion, which but little exceeds the rest, is a ray standing at about 225°, as in fig. 8. The edges sometimes appear a little concave. July 4. The fan radiates like an electric brush, strongly reminding me of a similar appearance in the last return of the Comet of Halley. It must have gained considerably in breadth, as it is now well seen in the comet eyepiece. I estimate its extent at more than twice that of July 2. It is very well shown in the micrometer eyepiece, power about 55, with which some measures are attempted. The radius towards the Sun, so bright on July 2, has now become very feeble, and has also advanced in angular position, as in fig. 3; thence the area brightens to a distinct beam, with a thicker and denser extremity; next to this is a space of feeble light, running up far towards the nucleus; and, further on, the circular limb seems to be indented, so as to make the form of the north cusp sharp and long an appearance increased by the backward curvature of the hinder boundary of the sector. But, excepting the beam with its broader end, which was sufficiently evident, these details were delicate and difficult. The measures of position, such as they were, gave for the south edge 207° (extremely uncertain), the luminous beam 251°, the north edge about 340°. : 310, 311 The length of the beam, from its time of passage, appeared to be about 1 minute of arc. July 5. The comet eye-piece showed the south edge of the fan more opened backwards, so that its position was more symmetrical; the luminous beam was broader, but less distinct. July 8. The sector has nearly lost its circular boundary, and it fades down into the coma; but it is still visible, of a dull yellow hue, with 460: a mean of three bad measures of position gave for the south edge, 227°; for the luminous beam, 2710. July 10. The sector seems to stand as obliquely as in the last observation; its circular boundary has disappeared, and the stronger ray is very obscure. July 15. Hazy; sector ill-defined, visible with 460, but contracted in angle, and of a brownish yellow hue. July 16. Much clearer; the increasing density of the adjacent coma barely leaves a separate existence to the sector, which, however, in the present sky, has recovered its angular extent. IV. The Coma. -This great mist faded away so imperceptibly that no attempt could be made to sketch its boundary; but I regret that I did not endeavour to form some idea of its extent at its first appearance. On July 4 the whole diameter of the head was very roughly estimated at 20'; July 10, 18'; July 15, 13'. My general impression, towards the close of the observations, was that it had increased in density and brightness as it diminished in extent: this seemed evidently the case on July 16, as, even with so high a power as 460, it was very conspicuous around and beyond the sector. Its most remarkable feature has been its change of colour. On June 30 the whole comet had a strong golden hue. July 10. I have entered it as distinctly white to the naked eye, and in the comet eyepiece tinged with blueish green or greenish blue. This hue was subsequently confirmed with suitable powers on the 15th, the nucleus appearing to have a greenish yellow cast. Considerable allowance must, of course, be made for the removal of the object from the ruddy vapour of the horizon, but still I think the fact of the change is at least highly probable. V. The Tail.—This magnificent appendage was chiefly remarkable for its near approach to us, and consequent apparent length, being far inferior in density and definition to that of "the Donati." On June 30 I traced it beyond the zenith, giving an extent of at least 90°. It widened out from the nucleus for some degrees, probably to a breadth of 3° or 4°, but was very undefined, and equally so on either side. The east edge appeared to strike off from the coma for a few degrees at a greater angle of divergency, but could not be traced by me as a separate branch; nor did I perceive, probably owing to the intervention of trees, the very interesting ray on that side, which, according to a communication and sketch with which I have been obligingly favoured by George Williams, Esq., of Liverpool, extended from the neighbourhood of the Comet's head as far as, and across, the stars of Cassiopea: the brightest part of this beam, it is stated by the observer, was at some distance from the Comet, and it appeared to recede from it until it was altogether lost.* The main stream was considerably convex towards the west, pointing at its origin to the left of Polaris, and subsequently bending back so as to involve that star, which was in its centre about 11h; but thence it appeared to the eye of another person, as well as my own, to take a fresh course, directed straight from the nucleus towards 3 and 7 Lyra, its extremity being lost in the space marked out by a Lyra, ẞ and y Draconis, and & Cygni. Its general aspect is 311, 3'12 Rev. T. W. WEBB: on the Great Comet of 1861. represented in fig. 6. By 13h its edge had reached Polaris, but moonlight then began to enfeeble it. About 11h 45m my wife called my attention to a faint ray of perfectly similar character, stretching under the square of Ursa Major, about 3° or 310 broad, having Ursa Majoris in its lower edge, and Cor Caroli about 1° above its upper, and traceable about half way from the latter star to Arcturus. It pointed to the Comet, but in the twilight no connexion could be made out. About 20m afterwards it had risen higher, so as to stand midway between and y Ursa Majoris; its further part had now become much more distinct than before, perhaps more so than any other portion of the ray, and its termination was plainly visible near Böotis; some time afterwards I could not see it. From this circumstance, and the character of its motion, opposite to that of the mass of the tail, I concluded it could be only a cirrus cloud brought up by the north-west wind, though the peculiarity of its direction caused me, fortunately, to record it; and from this impression, and my having missed the corresponding beam in Cassiopea (which, according to Mr. Williams, was somewhat the brighter of the two), I imagined for some time that the perspective appearance of the tail on this night did not accord with its immediate proximity, as calculated by Mr. Hind; but as the western ray was plainly seen by Mr. Williams at Liverpool about 12h 30m, passing midway between and ß Ursa Majoris, and reaching down towards the head of the Comet, I think there can be little doubt that it was really a part of the tail, whose rapid motion of closing up towards the axis indicated that it was then in the act of leaving the immediate vicinity of the Earth; and thus this most interesting appulse, if not actual conjunction, appears to have been verified by positive observation. Mr. Williams also had supposed that his two rays might be only streaks of cloud, and had been induced, like myself, to record them from the peculiarity of their direction: happily the intervening distance between the observers was such as to remove any suspicion of the kind. That gentleman's sketch, I ought also to observe, gives so great a breadth and so scattered a character to the central portion of the train, that it becomes naturally connected with these widely divergent lateral appendages. Under these circumstances it is not surprising that I should have failed in detecting any traces of a hollow structure, though I looked for them carefully. No anomalous ray could be perceived towards the Sun. July 2. The tail was now slightly concave, instead of convex, towards the west; it could be traced nearly to Wega, or about 80°; neither of its edges was at all defined. In the comet eye-piece its central region at some distance behind the nucleus appeared slightly fainter than its sides. Its general direction to-night coincided nearly with the right (inverted) side of the innermost envelope in fig. 2. July 4. Tail nearly straight; possibly a slight double curvature, first to the left (or west), then to the right, but it is quite uncertain. It appears more dense for some distance from the head; both sides are equally ill-defined. The nucleus seems to stand at the vertex of a wide but very ill-marked parabola, part of which is formed by the north edge of the fan, and within which was rather less light than at the sides; the coma, in passing off along each side of this space to form the train, was somewhat brighter on the north; but all this was so indistinct as to require close attention, and nothing like two separate streams could anywhere be seen, nor was there any anomalous ray. July 5. The tail appears, as last night, a little denser at its origin on the north, or orbitally following side; and rapid cross-sweeping with the comet eye-piece detects a slightly darker interior, commencing near the nucleus, but not traceable for any considerable distance. July 6. The tail is again slightly turned to the left. 312, 313 July 8. Tail about 14° or 15°, and streaky to the naked eye. I am not sure whether I have not noticed this before. In the comet eyepiece it had a narrow ray in the centre, or rather, a little way behind the coma, I saw nothing but a faint ray, about 5' broad by estimation, and several degrees in length. On the north side the coma passed off into a faint branch of about the same width, and perhaps 30' long., fading gradually away; on the other side I could find nothing corresponding. Hence I concluded that this branch and the longer ray were the two sides of a hollow tail, till further examination, and especially with the finder, convinced me to the contrary. In this little instrument the whole tail rose in one stream from the whole coma; and the ray, having been previously perceived, could be seen to form its axis for some distance. Fig. 4 is the appearance in the comet eyepiece; fig. 9 that in the finder. July 10. I studied the tail carefully, and think that I misconceived its structure the night before last: the two branches, as in fig. 4, are, after all, a double train with a darker interior. I was misled by its coming off from the coma with a sudden turn downwards (inverted): the lower is the fainter and shorter of the two branches, reaching about 2°; the other is much the longer; it is broader than on the 8th, but, notwithstanding a very transparent sky, less defined. There is no other branch on the opposite side, and it is obviously the edge, and not the centre of the tail. Fig. 4 still suits it well: a very careful scrutiny with the finder detects no central ray. The bend downwards is very visible with this little glass, and perceptible to the naked eye. July 15. Powers of 55 and 110 showed no dark interior, but it could be distinctly made out in the comet eyepiece, though not near the nucleus, and could be traced for about 1°. The streams on each side were nearly alike-possibly the orbitally preceding may be the more dense; the head still seemed, as it were, set on a little awry. July 16 and 23. Hollow structure difficult to be perceived. A few general remarks may be permitted at the close of these observations. It may fairly be inferred, from the absence of any phasis, that the visible nucleus either contained no concentration of opaque matter, or shone by intrinsic light. Its axial rotation seems improbable, if, as may reasonably be supposed, the more luminous rays always issued from the same portions of it. On the other hand, some amount of libration might be deduced from the varying angles of position of certain portions of the sector, if only the measures could be thought worthy of sufficient confidence. The similarity of the brilliant jet of June 30 to the streams which issued from the nucleus of Halley's Comet in 1835 is as obvious as that of the subsequently formed sector to some of the phenomena of the Comet of Donati; and the unsymmetrical arrangement, so evident in 1858, was again conspicuous. The sector was of later date than the envelopes, and much posterior to the perihelion passage. The descent of the envelopes upon the nucleus in the Comet's retreat from the sun corresponded with the similar process described by Herschel and Schröter in 1811; and this probably may have been the cause of the increasing apparent density of the whole coma. There were no indications of rotation in the tail. Any general curvature which it may have possessed was masked by its position; but minor deviations in direction were sufficiently evident. The obliquity of the sector and envelopes with respect to the axis of the tail might be thought to indicate that a stronger repulsion or a less resisted emissive force acted in one direction from the nucleus than in the opposite. The nebulous veils, without any difference as to extent, showed invariably greater Comet I., 1862. The Comet appears to have been first observed by Mr. Schmidt, at Athens, about half-past ten on the evening of July 2, near the stars 6, e,, Cassiopeia. It was seen about midnight by M. Tempel, at Marseilles, and by Mr. Bond, at Harvard College, on the evening of July 3d (see Ast. Nach. Nos. 1369, 1370, and 1374). Elements have been computed by Dr. Seeling, Mr. Hall, Mr. II. P. Tuttle, and Dr. Weiss ; those of Dr. Weiss, computed from the Athens and Marseilles Observations of July 2, 3, 5, are as follows: from which the position is laid down on a drawing which accompanied his letter. The altitude was 25° 48′ 30′′. The Moon had just set, and the Comet's position was made under the disadvantage of a bright Aurora, which was coruscating towards the zenith, from an arch of about 14° elevation, from N.N.W. to N.N. E. (mag.) The tail of the Comet was inclined to the E.S.E. (mag.), and measured (with unassisted vision) half a degree nearly, or about equal to fifty millions of miles. The nucleus was well defined, and equal to a star of the third or fourth magnitude, surrounded by considerable nebulosity of an irregular oval, perhaps paraboloidal. The jet apparently waved to and fro: this is however doubtful, and it may be an illusion, caused probably by the shooting corus cations of the Aurora. The most attractive feature of the Comet was the welldefined limb of the south or underneath portion of the tail. The instruments used were a common 3-foot telescope of 16 field, and a sextant, being all that the observer had; but there was the assistance of a pure and transparent atmosphere. Motion retrograde. The Council have great sorrow in notifying to the Fellows of the Society the decease of Capt. Jacob, within a few days after his arrival in India, and that the important expedition on which he had set out is thereby brought to a most unexpected and unfortunate close. As the next Annual Report will contain fuller particulars of his life and labours, and in particular of this the closing event, the Council now confine themselves to stating that Capt. Jacob sailed from England in the Hertfordshire, by way of the Cape, on the 20th of April last; and after enjoying good health on the voyage, landed at Bombay on the 8th of August, with a slight cold, which appears from the accounts received to have been increased during the exertions of superintending the landing of his family and instruments. He proceeded, however, within two or three days to his destination, Poonah, where medical aid was called in, in consequence of an abscess in the throat and an attack of Lieut. Chimmo (Canna Island, Hebrides, lat 57° N., long. inflammation of the liver which had supervened. Leeches Communications in reference to this Comet have been received from C. B. Chalmers, Esq., and Lieutenant Chimmo. Mr. Chalmers (Shanty Bay, County of Simcoe, Canada West), with his 5-foot equatoreally-mounted telescope by G. Dollond, saw the Comet, August 11, about 10 P.M., in the constellation Camelopardus; approximate Declination +80° 51', Comet moving north at the rate of about 50' in twenty-four hours; there was no tail, but a rather extensive coma; the nucleus bore a faint illumination of the wires. 316 Miscellaneous Intelligence. were very freely applied; and it is fruitless now to remark further than that, on the 16th, this admirable observer and excellent man was no more. 316 labours (carried on with unbroken activity for nearly sixty years) will be given in the ensuing Annual Report. Another severe loss has been incurred by the decease of an Associate of the Society, the veteran Astronomer Carlini, who died in his 77th year, after a short but painful illness, on the 29th of August, 1862. An account of his life and scientific Mr. Dawes calls attention to some typographical errors in his paper, "Saturnian Phenomena," as printed in the 8vo. edition of the last number of the Monthly Notices, viz., page 297, line 16 from the bottom, the word "side" should be in Roman letters, and page 298, line 7, the word "ring" should be in Italics; and line 38, the word "damp" should be "dense," the conjecture referred to being the existence of a pretty dense atmosphere on the rings. v.a. 1711412 NAT |