⚫825 249° 38'

June 11d 20h

Motion direct.

.8267 249° 51'

June 11d 23h

The first was computed from his own observations of 1861, July 5, 10, 15, and was published in India on July 25th; the second one was computed in August, substituting a French observation of June 30th, printed in the Journal des Debats, for the first of his own observations.

The observations are remarkable instances of what may be done with "a sextant and an old ship's chronometer." The Doctor writes, "My plan of observing was, to take every available evening a series of the Comet's distances from Vega and Arcturus, as near as possible to a mean of 9h 5m 33", Chinsurah Mean Time (3h 12m G.M.T.), and from these to compute the Comet's Right Ascension and Declination. With the found Right Ascension and Declination I computed its distance from a third star, ʼn Ursa Majoris, which I also measured; and it was only when the computed and observed distances agreed, or slightly differed, (say 1') that I considered the night's work good.

n

"In October 1858, with the same sextant, but with better eyesight and longer intervals (6th, 18th, and 30th), I found the elements of the Comet of 1858,

162, 163

If so, a comet with a known period of 80 years will take rank with Halley's. If they could be found, it would be interesting to recompute Mechain's calculations.

"On looking through Hind's list, I find a Comet in 1797 not very unlike, and another in 68 B.C., which I feel strongly disposed to identify with our Comet. From the obscure notices of the period in the Chinese annals, it appears to have had a perihelion distance of 8, and an inclination of 70°. Adding 68 to 1861, we have 1929, a near enough multiple of 80, when it is considered how much the cometary periods vary.

"No doubt all this has been discovered, and much more satisfactorily, in Europe; but it is new at least in this country. "W. S. M."

"Chinsurah, 19th July, 1861. "My observations were,—

The time is Greenwich mean time."

h m

July 5

3 12

172 31 30

66 40 20

10

3 12

206 10 15

59 41 17

"This differs considerably from Hind's May elements, as given in my former letter; but with an orbit almost perpendicular to the ecliptic, such differences are to be expected.

"From these elements I find that the Comet on the evening of July 5th was only eleven millions of miles from the Earth. Probably (for I have not calculated it) it was not much more than five millions, about the beginning of the month. This will account satisfactorily for its immense tail, and great velocity. I should be very thankful for any observations before the 5th and after the 15th. A week or two more will bring the determination from Europe of what the elements really are.

"Hind gives a group of four comets, with large inclinations, direct motions, and perihelion distances varying from 7 to 8, 9, and 1, for which periods have been computed of about 75 years. Another will now be added to the group; for I have no doubt that this comet is identical with the 1st of 1781, of which the elements were found by Mechain.

Extract of a Letter from Mr. Lassell.

(Communicated by Prof. De Morgan.)

"The principal work, however, I have hitherto done is the perfectly successful erection of the four-foot Equatoreal, on a most favourable site near Fort Tigné, on the north side of the Quarantine Harbour in this island. It differs a little from the lithographic drawing in the possession of the Society, as it is now erected in the latitude for which it was constructed, and not, as in that sketch, with the polar axis inserted in an excavation, to allow of its temporary use in the latitude of Liverpool. It is, indeed, much more substantially erected, with a view to its permanent efficiency in this far more favourable climate, where I trust it will do all that can reasonably be expected from 48 inches of aperture. I am glad to say that I have had no accident whatever in the erection, nor in the transmission of the mirrors, that which is now in the tube, after the dissolution and removal of its coat of varnish, having come out as fine in lustre as if it had been polished only yesterday.

"I have hitherto only cursorily examined a few objects, some of the minor conveniences of the apparatus not being yet quite completed; but I see enough to convince me that I have now a much more powerful and efficient telescope than I have ever possessed before. We are now passing through the most unsettled portion of the year, and I have found this so-called winter less favourable for the use of a large telescope than the same portion of the year 1852; I can, therefore, scarcely tell what the telescope will do under the most favourable circumstances. In turning it, however, upon the Nebula in Orion, I see so much more of its wonderful constitution, that I feel very ill-satisfied with my former drawings, and must begin I was, indeed, at first rather surprised, perhaps disappointed, not to see many more new stars; but, on reflection, I am inclined to think this may be satisfactorily accounted for by the great increase of brightness of the Nebula rendering the eye less sensible to very minute points of light. And this view is confirmed by observations of stars in the day-time with the transit instrument, which, I suppose from the greater light of the sky here, are scarcely so visible as in England.

anew.

"The fainter and interior satellites of Uranus, Umbriel

163, 164

and Ariel, though as much inferior in brightness to what have been called the bright satellites, as Rhea, or even Dione, among the satellites of Saturn, is to Titan, are conspicuous objects; and, with a magnifying power of 1060, not to be overlooked on any tolerable night. If Uranus has any other satellites than these, they must be very much smaller or fainter.

"The only indication of Saturn's ring at present visible is its shadow as a thin, hard, dark, rough line across or along the equator of the planet, which is now so full of sharp belts over almost all its surface, that it might be taken for a view of Jupiter with a smaller telescope. On the 25th instant all the satellites but Japetus were in the field of view at once; Mimas and Enceladus within a very few seconds, indeed, of the limb of the planet; the latter almost touching it. Another of the nearer satellites emerged from behind the preceding limb during observation.

"P. S.-It is, perhaps, scarce worth mentioning, and yet it struck me as either a fortunate coincidence or an evidence of care, that I have had no occasion to touch the adjustments of either Right Ascension or Polar Distance since the telescope was first directed to a celestial object; and, without having made any observations expressly for the purpose, I have not been made aware of any obvious error, in turning the telescope upon such objects as I have examined.

"9 Piazza Slierna, Malta, 28th January, 1862."

And, in a letter dated the 30th January, Mr. Lassell writes, "The detention of the mail allows me to add a postscript to my letter of yesterday, to inform you of my having discovered, last night, a new star within the trapezium in the great Nebula of Orion. It is situated near Theta, the principal star; appears to be about a full magnitude less than that known as the sixth star;' and is about six-tenths of its distance from Theta. Its angle of position from Theta is about 100° less than that of the sixth star;' and, consequently, points a little eastward of the star at the opposite angle of the trapezium. For verification I annex a diagram.

h m 8

13 25 54'4

9 10 46.25

64 17 28.31

Satellite.

Phenomenon.

Observer.

h m 8

Occ. reapp. first cont.

II 53 45°2

2 6.9

S.

S.

S.

Occultation observed at Highbury. By T. W. Burr, Esq.

1862, January 4th. The star x Aquarii disappeared at the dark limb of the Moon, at 1h 34m 49.6 local sidereal time, 6h 38m 475.1, Greenwich mean time. This occultation was instantaneous, but there had been a disappearance and reappearance about a minute previously, of an abnormal character. The Moon's dark limb was visible, and approaching the star extinguished it at 1h 33 12.6 L.S.T. After watching some little while, to be sure of the fact, I verified my time and re

166, 167

March 10, 1862.

Solar Eclipse of 31st December, 1861, observed at Goree, and at St. Louis, Senegal, by Officers of the French Imperial Navy.

By authority of the Duke of Newcastle, Secretary of State for the Colonies, Mr. Hind communicated to the Society the original of the Report of these observations, taken by the direction of the Governor of the French colony of Senegal ; Mr. Hind states that the observations are due to the warm

interest evinced by Capt. Washington, the Hydrographer of the Admiralty, on the occasion: he having forwarded a few instructions drawn up by the Astronomer Royal to the Governor of the Gambia, with a request that he would procure from the authorities at Goree a report of the eclipse.

The observers at St. Louis were MM. Vallon, Ribel, and De Marteville; those at Goree, MM. Poulain and Dutaillis. The eclipse commenced at St. Louis about oh 4m, and the last contact was observed at 2h 57m 36.1. At Goree the Moon had entered about one-tenth of the diameter on the solar disk at ob 3m 35, and the eclipse terminated at 2h 51m 18s.* For want of a telescope of sufficient power the red prominences were not observed at Goree. The following are extracts from the Report:

"Saint Louis.-A 1h 30m 50s pendant que le croissant du Soleil passe rapidement à l'occident de la Lune, une magnifique protubérance se détache du coté opposé à 12° environ au-dessus du diamètre horizontal du Soleil. D'abord voisine de la corne supérieure orientale, sa base en partie cachée par la Lune embrasse 5 ou 6 dégrés du disque solaire; le sommet, éclairé d'un beau rose, se dessine franchement sur une portion de couronne d'aspect rayonnant, jetant quelques ombres très mobiles qui descendent du nord au sud comme le feraient les ailes rapides d'un moulin à vent. Ces rayons d'ombre convergent au centre

du Soleil.

"Ce beau phénomène dure de 1h 30m 50s à 1h 34m 44, heure à laquelle la protubérance et tout jeu de lumière s'effacent derrière le disque de la Lune. Cette protubérance étant très voisine de la perpendiculaire à la corde du croissant solaire, son immersion a été suivie avec soin. La base à d'abord disparu, puis graduellement toutes ses parties, dans le tems du mouvement de l'éclipse; enfin le sommet, au moment ou l'épaisseur du croissant était mesurée au cercle 1' 10".

"Il est évident que cette mesure correspond à peu près exactement à la hauteur du sommet de la protubérance sur le disque du Soleil, auquel elle est sans nul doute attachée, ces deux éléments étant situés aux extrémités d'un même diamètre. "Nous croyons que la protubérance est l'effet d'un amas de

*The times throughout are mean solar time of St. Louis or of Goree, according to the place of observation.- ED.

167, 168

nuages solaires; le telescope permettait d'en compter les dentelures au nombre de trois principales sur son versant supérieur. La partie inférieure moins étendue paraissait en surplomb sur le bord de la Lune. Le sommet, mieux éclairé que la base, dont la Lune masquait le lieu de jonction au disque solaire, atteint son maximum d'éclat, une minute avant son immersion.

"Gorée. Faute de téléscope, on ne peut que reconnaître le beau phénomène de la couronne qui environne les disques superposés au point de produire l'effet d'une éclipse annulaire. "Saint Louis.- La portion de couronne visible à l'orient de la Lune embrassait un secteur de 60 à 70 dégrés. D'un beau rose près des disques des astres, les rayons allaient s'affaiblissant dans la teinte sombre du ciel. Sa structure était à rayons, et elle a paru suivre l'immersion graduelle de la protubérance.

"La lumière de cette portion de couronne a été observée à éclat; effet produit par les ombres rapides que nous avons signalées plus haut.

“Gorée.-Vers 1h 25m on voit des franges noires se dessiner sur le mur de la terrasse d'observation: à 1h 26m l'éclipse paraît centrale; une cercle lumineux existe autour du disque lunaire; son épaisseur est de de doigt; des aigrettes lumineuses émanent de tous cotés; à droite et à gauche elles sont parfaitement symétriques; au-dessus, il y en a une plus longue et plus large; au-dessous elles sont plus courtes.

"Il règne dans les environs une obscurité qu'on peut comparer à la lueur d'un crépuscule dans les plus belles régions de l'Europe. Vénus et trois autres étoiles paraissent au firmament à 2h 34m 30s; la distance de Vénus au Soleil a été observée 46° 30'.

"Saint Louis. - Trois groupes de taches ont paru dans le 2o quartier du Soleil, deux autres plus petits à la partie inférieure du 4o quartier.

"Ces taches ont en général un noyau brun dont les bords sont tranchés sur l'enveloppe vaporiforme qui la circonscrit. Cette enveloppe, d'une teinte neutre affaiblie, a un contour bien accusé sur le disque du Soleil.

"Nous affirmons que pendant la durée de l'observation aucune de ces taches n'a changé de position relative, de forme absolue, ni de teinte.

"Doivent-elles leur existence au déchirement de la photosphère qui laisserait apercevoir le noyau central du Soleil, ou son enveloppe de nuages obscurs, suivant Arago? Cette explication satisfait pleinement la vue. Sont-elles le résultat d'une accumulation de nuages solaires de même nature que les pro tubérances? Cette dernière supposition fort ingénieuse ne nous paraît cependant pas soutenable, et n'explique ni la figure étrange des taches, ni leur immobilité pendant 3 heures, ni enfin la permanence des effets de l'éclairage de toutes leurs parties.

"Le centre des taches principales renfermait des espaces lumineux disposés irrégulièrement. La Lune, dans son ascen sion, a successivement recouvert ces groupes; ils devenaient d'autant plus visibles que son disque s'en approchait d'avan tage. Aucune de ces taches en s'immergeant, ou en reparaissent, n'a subi la moindre altération de forme. Les cornes du Soleil se sont effilées sans distorsion apparente.

"Les baromètres au moment de la plus grande obscurité sont descendus de 763.5 à 762·5.

"Les thermomètres au Soleil de 34° centigrades à 230.6. "Les thermomètres à l'ombre de 28°.3 centigrades à 23°5. L'arguille aimantée n'éprouve aucune oscillation.

66

"Les deux hygromètres accusent 10 centièmes d'humidité en plus.

"Enfin, la face du Soleil a paru très homogène, à part quelques groupes irréguliers de facules lumineuses qui envi ronnent les deux petits groupes de taches inférieures.

"Gorée. Le thermomètre à l'ombre est descendu de 25°-8

à 20 dégrés. La courbe de la chaleur parait d'accord avec celle de la lumière.

"Le baromètre a varié entre 762 et 763.

"Le psycromètre, formé de deux thermomètres, un sec et un mouillé, donnait en centièmes, au moyen des tables, la quantité d'humidité renfermée dans l'air. Il a accusé 12 centièmes d'augmentation.

"Le phénomène des franges noires a été observé un instant avant l'occultation; elles avaient, sur une surface verticale dirigée sensiblement de l'ouest à l'est, une direction de 45° par-dessus l'épaule gauche; leur largeur et leur espacement étaient à-peu-près égaux et mesuraient environ 10 centimètres. La nuance était une ombre claire qui a paru dégradée sur les bords.

"Avant et après l'occultation, les animaux domestiques et les plantes ont été influencés comme à l'approche de la nuit et au lever du jour.

66 Il y avait à Gorée un raz de marée exceptionnel. "Saint Louis.-Vénus a paru dans le S. E. au moment de la plus grande obscurité. Les édifices blanchis à la chaux paraissaient gris jaunâtres. Le rouge conservait sa couleur. La moindre épaisseur du croissant solaire a été mesurée 57′′ à 1h 30m 49"."

Discovery of a Companion of Sirius.

170, 171

Discovery and Elements of a New Minor Flanet, .

In the Ast. Nach., No. 1353, Prof. Bond communicates also the discovery of this new Minor Planet, under the following circumstances. Mr. Safford having had occasion to refer to the positions of Maia, obtained by Dr. Peters at Hamilton College, and published in Brünnow's Astronomical Notices, No. 20, was surprised to find that only three of the series, namely, the places for 1861, May 9, 11, and 12, could be reconciled with the Cambridge (U.S.) observations. A reference to Mr. Hall's Ephemeris of Maia (Ast. Nach., No. 1315), showed that the Ephemeris represented the Cambridge observations of Maia from April 9 to May 27, nine in number, and also the first three of those of Dr. Peters, but that it did not represent the later observations of Dr. Peters. It was at once conjectured that in the interval between May 12 and May 29, when clouds and moonlight intervened to prevent a close following of Maia, which was only of the 13th mag., Dr. Peters had lost its trace, and on resuming his observations had fallen on a new Planet. Mr. Safford, after obtaining corrected positions of the comparison stars of Dr. Peters, obtained the following elements,—