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water. Surely this little experiment must convince the most obtuse that the moon does rotate on its axis.
Heckington Hall, Sleaford, Lincolnshire: W. LITTLE.
P.S.—I expected no other answer to ray pea question from such an able correspondent as Mr. Dawes.
TO THE EDITOR OF THE ASTRONOMICAL REGISTER.
Sir,—Allow me to ask for replies to the following questions:— 1. How often does the earth turn round its own axis while travelling around the sun?
a. Why have we 365J solar days, and 366J sidereal days, and why do they differ exactly by unity?
3. Why are the solar days variable, and the sidereal days always of uniform length?
4. * Is axial rotation the only way of turning round?
5. What would be the effect if the moon turned about her axis in the contrary direction once every time she orbitated round the earth?
6. After walking half round a circle, should we face the same point of the compass as if we walked straight across the circle?
7. Is parallel motion in a circle a single movement or a double motion f
8. * Must a body turn about its own centre of gravity in order to present all parts of its surface to every point of the compass?
Dec. 8, 1864. CASSANDER.
The Moon's Rotation.—The following note has been handed to us by a correspondent:—In the Philosophical Transactions, vol. i., p. 89, in an account of Dr. John Wallis's " Hypothesis of the Flux and Reflux of the Sea," the following passages occur:—" Now that the earth has such a motion about its own axis, whereby it might be fitted to carry about the moon, is evident by its diurnal motion. And it seems as evident that the moon has Not, because of the same side of the mom always turned towards us ... . Therefore, we have reason
to believe, not that by the moon's motion about its axis, &c
but that by the earth's revolution about its axis in twenty-four hours, the moon should be carried about it in about twenty-nine days, without any motion on its mm axis."
Lunar Observations.—We have to acknowledge the receipt of copies of the Forms promised by the Lunar Committee of the British Association for the Advancement of Science for aiding in the formation of a Catalogue of Lunar Objects, and for the construction of a Map of the Moon, in which each object in the catalogue is to be inserted. Form No. 1 is for recording observations; Form No. 3 is for the registration of objects; and Form No. 4 is for computing the positions of objects.
NOTES AND GLEANINGS.
Bremiker's Logarithms Dr. Weiss has published the following
errata in this well-known and valuable work: we transfer these to our pages, as many of our readers may be glad to be made acquainted with them.
Celestial Chemistry is the title of an important article by Mr. T. W. Burr in the January Intellectual Observer. The writer enters at considerable length into recent speculations deduced from spectroscopic observation, and the paper is accompanied with an excellent coloured diagram of the spectrum, showing the stellar and solar lines in correspondence. There is also a drawing of the apparatus employed, of which, in a future number, we hope to present a copy to our readers.
Planetary Distances.—Mr. K. S. Browne communicated to the British Association the following series of numbers as representing more accurately than " Bode's Law the distances of the planets:—
Encke's Comet.—The following approximate ephemeris of this short-period comet has been computed by Mr. Farley, and was presented to the Astronomical Society by Mr. Hind :—
Large Fireball.—Account of a large fireball seen at Poggio Ubertini, near Florence. (Extract of a letter from Madame Baldelli):
"On the 1st of last month (November), wandering out after dark, I saw at about six minutes to 11, in the direction of the Stella Polaris, one of the most remarkable meteoric appearances in the sky I have ever seen (and I have seen some very curious ones). A white globe of fire many times larger than the full moon seemed hanging almost motionless in the air; a large portion of the surrounding heavens was lighted up by it, so much so that my head being turned away from it, I mechanically apprehended it was moonlight, though, had I thought at all, I should have known that no moon was at that time in sight; but a bright shimmering of light on a tall bay tree not far from me recalled my attention, and turning I saw this fireball, white for a moment, shades of orange and blue passing over its surface, the latter gaining on the former. After a full minute's time (after I had turned towards it) it disappeared suddenly—vanishing, not appearing to move from where it was; only just before its disappearance a smaller ball was seen immediately "below it, of a fiery orange colour, the first one appearing at that moment of the same hue. I called Baldelli often whilst looking at it, but he had left the drawing-room, which opened on the grounds, and did not hear me. The servants in the kitchen (also on the ground-floor, but far away from where I was) thought the bright light came from sheet lightning."
Literary And Philosophical Society Of Manchester At the
meeting on November 10, Mr. Baxendell read a " Note on the Period and Changes of the Greenwich Variable in Vulpecula, No. 1773 of the Twelve-Year Catalogue."
"In No. 1500 of the Astronomische Nachrichten, Dr. Schonfeld, Director of the Observatory at Mannheim, expresses a doubt as to the variability of several of the stars in Mr. Chambers's Catalogue of Variable Stars. One of the objects which he thus points out as doubtful is No. 1773 of the Greenwich Twelve-Year Catalogue, which was entered in Mr. Chambers's list on my authority, as I had satisfied myself from occasional observations made since 1861, that its light was subject to periodical changes, though not to the extent indicated by the observations of Messrs. Rogerson and Glaisher, made in 1837. I have since reduced my observations, and have obtained from them the times of maximum and minimum brightness. The mean of the two values of the period is 67-92 days. The interval from minimum to maximum brightness is 30-8 days, and from maximum to minimum 37-1 days. This variable, therefore, like many others, increases in brightness more rapidly than it diminishes. Its magnitude at maximum is 8-8, and at minimum 9-8, the range of variation being therefore one magnitude. It is one of the highly-coloured stars, both Mr. Hind and myself having always noted it as "being very red."
Observations of the same star, and of five companions close to it, by Mr. G. Knott, of Cuckfield, Were also communicated to the Society by Mr. Baxendell.
CORRESPONDENTS' QUERIES AND REPLIES.
Are there any indications of water action on the moon? C. E. -W.
Can you give any information as to when the new edition of the Cycle will he published? A Subscriber.
Now that we seem approaching the close of the "Lunar Rotation" controversy, there will be more space for matter of perhaps more general interest and utility. Yet it is a special value of the Astronomical Register, that it admits of free interchange of thought; if it brings out errors or ignorance, as well as elicits truth and information, it is by no means to be regretted. Should the Moon controversy be revived ten years hence, the Register will furnish plenty of matter for such lucubration! G. J. W.
Lescarbatjxt's Planet.—D. A. B. writes apparently under the belief that this planet may be expected to transit across the sun regularly twice in every year: so it would if it revolved in the plane of the ecliptic; but as its orbit is inclined thereto, it only appears on the sun s disk after certain (at present unknown) intervals, as is the case with the other inferior planets. Not enough is yet known of this new planet to make it possible to foretell these occurrences, though the day may come. G. F. C.
Uranus.—An almanac and a celestial atlaSj plus a little experience, will enable any one to find this planet. It shmes with a steady light, essentially different from that of stars of similar magnitude. When found it is not worth looking at, except by those possessing very large telescopes. I think T. D. would do well to husband his patience for something more interesting, unless he has at command an 8 or 10 inch refractor. G. F. C.
Comets.—In the opening chapter of Mr. Hind's work on The Comets there is this passage :—" The Chinese astronomers, though they looked upon comets without any fears of their malignant agencies, had a very fanciful opinion respecting them, which nevertheless led to the frequent observation of the position of these bodies," &c. What was the fanciful opinion alluded to P—Notes and Queries.
Omar Cheyam, Abouliiassan Kuschiar, And Jarnab'u-din.— The first of these three is said to have been one of the eight astronomers Jelal'u-din Malek Shah employed to regulate the Persian state calendar about A.d. 1075; the second is mentioned in Herschel's Outlines of Astronomy (3d ed. p. 365); and the third is said to have regulated the Chinese calendar in the 13th century. Fuller information respecting them and their works, with references to authorities, will greatly oblige J. B.—Notes and Queries.