Page images
PDF
EPUB

226, 227

RECENT PUBLICATIONS.

Recent Pullications

Sur l'Intégration des Equations Differentielles dans le Problèmes de Mécanique :- Applicatim de la Méthode de M. Hamilton au Calcul des Perturbations de Jupiter. Par M. Houel, Professeur de Mathématiques au Lycée à Alençon. Paris, 1855.

In the first of these papers the author has developed the general method of dynamics proposed by Sir William Hamilton in two papers published in the Philosophical Transactions for 1834 and 1835, taking into consideration the subsequent extensions by Jacobi. In the course of his investigation the author has demonstrated several general theorems of Celestial Mechanics, including the theorem of the invariability of the mean distances, taking into account all the terms of the order of the cube of the disturbing force.

The second paper contains an application of Sir William Hamilton's method to the computation of the mutual perturbations of Jupiter and Saturn. In the course of his labours the author has obtained several important corrections to the numerical results relative to the same subject, given by M. Pontécoulant in his Théorie Analytique du Système du Monde.

227, 228

Professor Mädler has recently published a pamphlet containing some details relative to the total eclipse of the sun which is to occur on the 18th of July, 1860. The circumstances of the eclipse are rigorously calculated for 112 positions in Spain, Portugal, and Algiers, the places of the sun and moon being derived from an ephemeris computed by Prof. Wolfers from the Solar Tables of Hansen and Olufsen, and the Lunar Tables of Hansen. The author has given a graphic representation of the same results, and in another figure he has exhibited the aspect which the heavens may be expected to offer at the city of Saragossa during the totality of the eclipse. Besides the planets Mercury, Venus, Jupiter, and Saturn, it contains all the stars of the first two magnitudes, and several of the third magnitude which will then be above the horizon. The four planets will be situate very near to the sun in the form of a rhomboid. The stars Regulus, Procyon, Sirius, a and ß Orionis, Castor, Pollux, Capella, Aldebaran, Vega, Arcturus, and Spica Virginis, will all be above the horizon. Professor Mädler's paper contains some useful suggestions for observing the eclipse.

Astronomical and Meteorological Observations made at the Radcliffe Observatory, Oxford, in the Year 1857. Under the Superintendence of Manuel J. Johnson, M.A., Radcliffe Observer, vol. xviii., Oxford, 1859.

This volume, the sheets of which were passing through the press at the time of the death of its lamented author, contains the usual observations with the transit instrument and meridian circle. These are followed by a catalogue of the stars observed in the year 1857, showing the result of every observation. The number of stars in the catalogue is 1398. The volume closes with a very full account of the meteorological operations executed at the observatory in the course of the year.

Almanaque Nautico 1860, Calculado de orden de S. M. para en el Observatorio de Marina de la Ciudad de San Fernando. Cadiz, 1858.

This volume contains two useful graphic representations of the path of the moon's shadow on the occasion of the total eclipse of the sun which is to occur on the 18th of July, 1860. The first of these relates to the track of the shadow on the surface of the earth in general; the second is specially designed to exhibit the circumstances of its passage over the Spanish territory.

[merged small][merged small][merged small][merged small][ocr errors][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][ocr errors][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small]

Note sur la Comète de Donati.

Par M. le Professeur E. Plantamour. (Tiré des Archives des Sciences de la Bibliothèque Universelle de Genève.)

This pamphlet, embodying Professor Plantamour's observations of Donati's comet, forms a useful accession to the materials of a similar character which have already been published. The determinations of the position of the comet extend from August 28 to October 18. There are some valuable drawings of the physical phenomena exhibited by the comet during the period of its greatest splendour.

The increase in the intensity of light shows the following results:

April 18=1; April 30= 18; May 16=4'2; June 19'7; June 30=0*5.

Biela's Comet.

In No. 120 of Gould's Astronomical Journal Professor Hubbard has determined the clements of the two nuclei of this comet for the perihelion passage of the present year, and has computed an ephemeris of their positions for every fourth day, extending from 1859, March 23, to July 21. Mr. Hind, as

Superintendent of the Nautical Aimanac, has published an extension of this ephemeris, giving the places for every day from April 20 to July 24. Copies of Mr. Hind's circular have been forwarded to the various private observatories throughout the country.

The following letter from Mr. Maclear to Admiral Smyth contains some further intelligence respecting Donati's comet:"At page 67 of No. 2, vol. xix. of the Royal Astronomical Society's Notices, it is stated that Donati's Comet was first seen at Rio de Janeiro, on October 7; Buenos Ayres, 7; Loando (W. Africa), 7; Cape of Good Hope, 11.

"Omitting Loando, for the geographical reason of that station being some 24 degrees to the north of the Cape, the Comet should have been seen at the other stations about the same date nearly, weather permitting. I give from our Meteorological Journal the state of the sky at the evening Göttingen mean times of observation, viz. at Cape mean times 5h 34 and 9" 34" P.M.; as follows:

[merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][ocr errors][merged small][merged small][merged small]

:

[blocks in formation]

"The number 9 implies that nine-tenths of the visible hemisphere were clouded at the time of observation; 7, that seven-tenths were clouded, &c. &c.; from which the state of the sky between 5" and 9" may be inferred.

"It is said to have been seen at Green Point for a few minutes on the 9th, through a break in the clouds.

"On the 10th I saw the head while pointing the telescope, but it was covered by a cloud immediately after; and I remained at the telescope for about an hour, hoping for an opening. The weather cleared up on the 11th.

"The numbers for the 7th and 8th will explain why it could not be seen on those evenings.

"We have pursued it through a considerable segment of the orbit, having hauled off only a fortnight back!

[ocr errors]

"The number of stars compared with it amount to about 120. Cape of Good Hope, 1859, March 19."

[merged small][subsumed][merged small][subsumed][merged small][subsumed][subsumed][merged small][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][merged small][merged small][ocr errors][subsumed][merged small]

Five of the principal groups were visible to the naked eye, namely, those of June 4, August 28, October 16, November 9, and November 29. The group of November 9 had a diameter of 65" 7 - 683. The diameter of the group observed on the 29th of the same month amounted to 205" 8. The greater number of spots appeared in the southern hemisphere. The two most extensive groups were those of March 17 (diameter from east to west 243"-8) and September 30 (diameter 321"-3, also from east to west).

Equatoreal Instrument for Sale.

The object-glass was the property of the late Dr. Ritchie, and was examined and an account of its performance given by the late Rev. Samuel King, in vol. v. of the Monthly Notices of the Society. The aperture of the object-glass is about 73 inches; it is furnished with several astronomical and one terrestrial eyepiece, a finder, illuminating apparatus, and parallel line micrometer.

The mounting is of the Frauenhofer kind, with circles reading by verniers to one second of time and ten seconds of declination, and horary motion by clockwork. The entire mounting was prepared by Troughton and Simms.

This instrument may be seen at the observatory of the late A. K. Killmister, Esq., at Leek, Staffordshire; and any further information obtained either from Messrs. Troughton and Simms, or G. R. Killmister, Esq, West Bank, near Macclesfield.

The price asked is 250l., less than half its original cost.

[merged small][ocr errors][merged small][merged small][merged small][ocr errors][merged small][ocr errors][merged small][merged small][merged small]

Sir William Keith Murray has recently forwarded to the Society a printed description of the observatory erected by him a few years ago at Ochtertyre, Perthshire. He has also sent along with this description a set of plans, which serve to give a clear idea of the different parts of the building. It is generally known to astronomers that Sir W. Keith Murray possesses an equatoreally mounted refractor of 9 inches clear aperture, by Messrs. Cooke and Sons of York. Results indicative of the favourable performance of this instrument have been published from time to time in the Monthly Notices.

[blocks in formation]
[ocr errors][ocr errors][ocr errors]
[ocr errors]
[merged small][merged small][merged small][merged small][ocr errors][ocr errors][ocr errors][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors]
[ocr errors]
[blocks in formation]

read

77

[same in least terms].

16

22+

7

e'4

[ocr errors]
[ocr errors]
[ocr errors]
[merged small][ocr errors]

4 evection

[ocr errors][ocr errors]

~ 3e +

e3

5

es

[merged small][ocr errors][merged small][merged small][merged small][merged small][merged small]
[merged small][ocr errors]
[merged small][merged small][merged small][ocr errors]

e"

[ocr errors]

I

[blocks in formation]

25 e' 384

[blocks in formation]

e's

[merged small][ocr errors][merged small]

233, 234

Note from the ASTRONOMER ROYAL.-Mr. WEBB, Traces of Eruptive Action in the Moon.

234, 235

VOL. XIX.

May 13, 1859.

No. 7.

[blocks in formation]

Notice of Traces of Eruptive Action in the Moon.
By the Rev. T. W. Webb.

The inquiry as to the continuance of volcanic or explosive action on the surface of the moon must be admitted to be a

very interesting one. Astronomers are generally agreed as to its entire cessation on any conspicuous scale; but this would not necessarily infer the impossibility, or even improbability, of minor eruptions, which might still continue to result from a diminished but not wholly extinguished force. Till the publication of the labours of Beer and Mädler the necessary data for the determination of the question were very imperfect; and since that time the general impression would seem to be adverse to the idea of any physical change. Before, however, it is entirely acquiesced in, it may be well to see whether any evidence of an opposite nature exists. Want of leisure has hitherto prevented me from entering upon the subject in any other than the most incidental manner; but I would request permission to direct attention to one or two regions where an accurate investigation might be desirable.

One of these is the spot named Cichus, near the south extremity of the Mare Nubium. Here, many years ago, in comparing Schröter's drawings with the moon, I was struck with the apparent enlargement of the small crater which has defaced one side of the ring. On procuring the map of Beer and

Mädler I found that they had also seen it enlarged. Could we, in this instance, depend upon the older drawings, we might reasonably infer the probability of a change since the year 1792. Schröter was, undoubtedly, a coarse draftsman, but still he was faithful and careful; nor does there seem any appearance, but the reverse, that his designs were copied from one another to save trouble; if not, the agreement of three separate figures seems fair evidence that this little crater was not then of its present magnitude.

The second case seems more satisfactory. It is that of the spot Messier, in the Mare Fæcunditatis, where two small craters lie side by side at the end of two parallel white streaks, resembling the divided tail of a comet. In consequence of an observation of Schröter, Beer and Mädler directed their attention especially to this region, and examined it more than 300 times between the years 1829 and 1837, with the result that the two craters were perfectly and singularly alike in size, shape, height of ring, depth of cavity, and even the position of some peaks upon the rings. I cannot say that I have ever been able to obtain a perfectly distinct view of this spot, from atmospheric causes; but every sight I have had of it has strengthened my impression that this remarkable similarity no longer exists. I first noticed a difference in the aspect of the two craters, 1855, Nov. 14. Since that time, in the occasional use of four instruments of very different size and power (one, an object-glass of 5 inches by Alvan Clark, now in my possession), I have invariably felt convinced that neither in size, form, or depth, are those two craters any longer precisely similar, but that, on the contrary, under suitable angles of illumination, such as must have repeatedly occurred during the 300 examinations by Beer and Mädler, the difference between them is obviously so great as to indicate some permanent alteration in the surface during the space of twenty years. May 12, 1859.

Sur la Variation Séculaire du Moyen Mouvement de la Lune. Par M. de Pontécoulant.

(Communicated by the President.)

"Dans la théorie de la Lune qui forme le quatrième volume de ma Théorie Analytique du Système du Monde,* j'avais adopté pour l'expression analytique du coefficient de l'inégalité séculaire de la longitude de la Lune, la formule trouvée par M. Plana dans son important ouvrage sur la même Théorie, mais depuis cette époque j'ai refait moi-même le calcul des différents termes qui composent cette expression, et j'ai trouvė, en négligeant les quantités dépendantes de l'excentricité et de l'inclinaison, pour déterminer l'inégalité dont il s'agit, l'équation suivante:

[merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small]

remarque dans les coefficients des termes dépendants des puissances de m' et m7, tiennent sans doute à quelques incorrections qui se seront glissées dans la suite de ces longs calculs et qu'il sera facile de faire disparaître en les soumettant à une nouvelle révision. Mais si l'on compare l'expression précédente à celle donnée par M. Adams dans le No. du Compte-Rendu Mensuel des Travaux de la Société Royale Astronomique du 8 Avril, 1859 (p. 207), on voit que la discordance se fait sentir dès les termes de l'ordre m1, ce qui provient de la considération de nouveaux termes que M. Adams a cru devoir introduire dans les formules analytiques d'où cette expression est déduite et auxquels on n'avait point en égard jusqu'ici. Or l'influence de ces termes est considérable puis qu'elle ne va à rien moins qu'à réduire à 5"-7, l'accélération du moyen mouvement lunaire dans un siècle, c'est à dire, à la moitié de la valeur à-peu-près qu'on était habitué à lui attribuer jusqu'à présent et à détruire, par conséquent, l'admirable accord qui semblait exister sur ce point entre la théorie et l'observation. Cette conséquence seule paraîtrait déjà rendre très problématique l'existence des nouveaux termes introduits par M. Adams, et il est, en effet, facile de démontrer, par une analyse très simple, que l'intégration des formules différentielles du mouvement lunaire ne produit dans l'expression de l'inégalité séculaire du mouvement moyen aucun terme différent de ceux qu'on a été accoutumé à y considérer jusqu'ici. J'aurai l'honneur d'adresser prochainement à l'Académie une note détaillée sur cet objet, et j'ose espérer qu'elle voudra bien, attendu l'importance de la question, lui donner une place dans le précieux recueil de ses mémoires, mais j'ai cru qu'il était indispensable de ne pas laisser passer, sans en faire l'objet d'une réclamation immédiate, une assertion qui aurait pour conséquence de jeter du doute sur l'un des plus remarquables résultats de la théorie du système du monde. "Paris, May 28, 1859."

[merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][ocr errors][ocr errors][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small]

Extract of a Letter from Prof. Hansen to the Astronomer Royal, dated Gotha, May 31, 1859.

"Delaunay's Säcularänderung der mittleren Mondlänge muss ich entschieden für unrichtig halten. Ich habe folgende drei Resultate durch die Theorie erhalten :

(1)

+11′93, Ast. Nach. No. 443,

(2)

+11'47,

...

No. 597,
(3) +12 120, in den Mondtafeln angewandt.

"Die Bestimmungen (1) und (3) sind durch zwei total von einander verschiedene Methoden erlangt, die ich in der Explication der Berechnung der Mondstörungen, die ich jetzt in Arbeit habe, erklären werde. Die nahe Uebereinstimmung verbürgt die Richtigkeit meiner Methoden und Rechnung. Die Differenz ist nur o".25.

"Die Bestimmung (2) ist nach derselben Methode wie (3) berechnet, aber ich hatte bei der Berechnung von (2) zu wenige Glieder hinzugezogen, daher rührt die grössere Differenz.

"Worin der Fehler von Delaunay liegt, kann ich in diesem Augenblick nicht sagen, aber man kann als nicht unwahrscheinlich annehmen, dass bei der Entwickelung der Mondstörungen nach den Potenzen von m, Glieder, die mit sehr hohen Potenzen multiplicirt sind merklich werden können.

Ueberhaupt hat man ja gar keinen Beweis von der Convergenz dieser Reihen, und sie müssen nothwendig bei vergrössertem Werthe von m divergiren. Ich habe bekanntlich diese Art der Entwickelung gar nicht angewandt, sondern von Annäherung zu Annäherung die erhaltenen Störungen in die

[merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][ocr errors][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][ocr errors][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][ocr errors][merged small]

238, 239

Occultation of Saturn.

[merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small]

Notes by Mr. Main [M.].-The instrument used was the Sheepshanks' equatoreal; for the disappearance the eye-piece used was No. 4 with a high power, probably about 300; for the reappearance No. 1 was used, power about 100. The only points of interest noticed were, first, that at the disappearance when the moon's edge (unenlightened) was passing over the shadows lying on the apparently upper portion of the ring behind the ball, a curious flickering kind of light was produced as if disappearing and reappearing. Secondly, that at the reappearance of the planet, the faintness of its light as compared with that of the moon was very striking, and this might perhaps produce a trifling error in the observation of the first reappearance, which was however considered to be tolerably accurate. Mr. Main also observed the disappearance of a star of the 8th magnitude, which took place accurately at 9h 11m 36.9 Greenwich Mean Solar Time; it was afterwards ascertained to be identical with one which is numbered 17237-8 in Lalande's Catalogue.

By Mr. Glaisher [G.]-With the 39-inch achromatic telescope and a solar chronometer. The power was very low (only about 30) and the planet very faint; little confidence was felt in the observation of the first disappearance, and it was considered likely that it was fully a second too late. It was impossible with so low a power to detect the first reappearance at the bright limb. The observations of final disappearance and reappearance were considered good. The interval of time after emersion before the planet was distinguished with the naked eye was remarkable, and amounted to at least ten minutes.

By Mr. Dunkin [D]. With the 46-inch achromatic telescope in the Octagon Room, and a sidereal chronometer. At the disappearance the moon and Saturn were exceedingly tremulous, and it was found impossible to use more than a very low power (about 40); the observations were considered doubtful, particularly that of the disappearance of the ball, in consequence of the indistinctness of the planet. At the reappearance, Saturn was very faint, and the images were still unsteady; they were, however, much better than at the disappearance, so that it was found practicable to use a considerably higher power (about 150), the observations being all considered satisfactory.

By Mr. Ellis [E]. -- With the altazimuth, and a power of about 100. The observations were all considered satisfactory.

[ocr errors]

239, 240 By Mr. Criswick [C]. With the telescope formerly at tached to the west equatoreal, placed in the Octagon Room, and a solar chronometer. The observations of the disappearance were considered satisfactory, but those of the reappearance rough, in consequence of the extreme faintness of the planet. The power used was about 70.

By Mr. Lynn [L]. With the north equatoreal, and a power of about 60. It unfortunately appeared that at the disappearance the moon was hidden behind one of the turrets of the observatory, and no observation therefore could be made. The planet at the reappearance was very faint, and the first reappearance was therefore not caught, nor could satisfactory observations of the reappearance of the ball be obtained; that of the final reappearance was, however, considered accurate.

[merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small]

Observed by William Simms, Jun., Esq.

The telescope employed was of 4 inches' aperture and 57 inches focal length; power 200.

The dark limb of the moon, which was clearly seen previously with a low power, passed steadily over the planet, without the slightest distortion appearing to either body, the unobscured portion of the planet retaining its usual light up to the disappearance of the edge of the ring.

The reappearance, which was carefully looked for, took place at a very rugged part of the moon's bright limb, and escaped observation until a considerable part of one of the ansæ of the rings was projected; so feeble was the light that I could not, for three or four seconds, believe it to be the planet. When the body was advanced about two-thirds of its diameter, I saw the band of dark shade over the planet, accompanying the edge of the moon, similar to the appearance noticed by myself and several observers at the last occultation of Jupiter; and which I now believe to be caused by the violet fringe of the secondary spectrum, seen round all very bright objects in refracting telescopes.

May not the projection of stars upon the moon's limb, frequently seen at occultations, be caused by the ray from the star having to pass through this violet fringe in its passage to the eye at the time of contact? Telescopes differing greatly in the amount of this colour might account for the irregularity of the observation of this phenomenon; and which, as far as I am aware, has not been seen in reflecting telescopes.

Observed by J. W. Jeans, Esq., at Grantham.

The time of first contact is uncertain to one or two seconds, also that of first reappearance; but it is, I think, more accurate than the former; the times of total immersion and emersion

« PreviousContinue »