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voluminous a work as The Cycle is a consideration. A considerable number of objects, moreover, are added to this collection which do not appear in The Cycle.

But Mr. Darby's compilation does not completely satisfy us; and, in particular, we could have wished that the pages had been arranged with a greater regard to distinctness and perspicuity. According to the present plan, the objects, with their positions, magnitudes, descriptions, &c., are given in continuous lines in the same paragraph, all being mixed up together, as it were, in the same sized type. This we know from experience will prove exceedingly teasing and unnecessarily confusing when the book is consulted in the dim light which alone should be permitted during observations. We are quite aware indeed that it is extremely difficult, almost impossible, to so arrange a catalogue that it shall be at once clear, concise, and complete, and be equally useful to the observer with a telescope ordinarily mounted and the possessor of an equatoreal instrument. We are of opinion, nevertheless, that in this respect the work before us admits of considerable modification and improvement, which could be easily effected.

The book bears many indications, also, of having been hastily put together; and we fear the already lengthy list of corrigenda Jails to comprise all the errors to be found in the volume. Among other inaccuracies we especially notice that seconds of arc are sometimes misprinted for seconds of time; "dumbell," too, is surely not the correct orthography of the familiar designation of "27 M. Vulpeculse!" We would ask Mr. Darby, moreover, why, in the references made to "Bishop's" catalogue, "Bishop's" magnitudes, See., some distinct allusion was not made to the fact that that able and experienced observer, the Rev. W. R. Dawes, was the working astronomer ?—Mr. Bishop undoubtedly being one of the munificent patrons of the science. We certainly are at a loss to understand how every turn of a pinion working in a wheel of 360 teeth fixed to the axis of the telescope will move it one degree! (p. xiii.) It strikes us that the author has not been at the pains to convey his meaning in sufficiently precise terms.

We have felt it necessary to make these critical remarks in order that the author's attention may be drawn thereto, and that in a future edition he may re-arrange the plan of the work, and correct the many errors therein, which we cannot help thinking must be ascribed to over-haste in its preparation. On the whole, however, we consider the Astronomical Observer to be a desideratum to the amateur, from which, if used with a little caution, he, will derive assistance in acquiring a knowledge of celestial objects.

Le Ciel: Notions cFAstronomie a V Usage de la Jeunesse et des Gens du Monde. Par A. Guillemin.

This elegant book will be warmly welcomed by the amateur world; but this makes it the more to be regretted, that m his account of tho discovery of Neptune the author has entirely omitted the name and labours of Adams. As a Frenchman he may well be proud of LeVerrier; yet in thus acting he has not told the whole truth I It is, however, a very magnificent astronomical volume, and its numerous illustrations are correctly drawn and admirably ongraved.

CORRESPONDENCE.

N.B.—We do not hold ourselves answerable for any opinions expressed by our correspondents.

DATES PREFERRED BY FIREBALLS.

TO THE EDITOR OF THE ASTRONOMICAL REGISTER. Sir,—As fireballs of large size have lately appeared in more than ordinary numbers, perhaps some of your readers have felt the want of a correct guide or indicator to the dates, when a watch may be kept for such appearances with the best advantage. This guidance is yet

Earticularly necessary, as there are some dates when fireballs can ardly at all be expected to occur. But on other dates the year can hardly pass without an occurrence of this kind taking place in our own country or abroad. The trial which the accompanying diagram (see plate) has received during the past year is sufficiently successful to recommend it, without any further discussion, to the attention of your readers; but a brief description of its arrangement and a few particulars of the observations may at the same time not be quite devoid of interest. The diagram was constructed, before the commencement of the present year, from an extensive catalogue of fireballs of old and recent date, contained in the volume for 18 60 of the "British Association Reports," by correcting the dates of the older meteors for precession, and reducing the whole to the fixed equinox of 1850. In this form of Mr. Greg's Catalogue the prominence of particular dates is remarkably well defined; especially the absence of meteors on the 25th days of every month, August and September alone excepted, which are maxima, and the coincidence of several maxima with dates already distinguished by the falls of star-showers or of meteoric stones. The latter dates are enclosed by brackets in the diagram wherever they occur among the dates preferred by fireballs. The double brackets refer to the falls of meteoric stones. Since the time of its construction, the following star-showers, aerolites, and fireballs have occurred, and been observed to verify the indications of the diagram:—

1. 1863 Nov. 29; large fireball, Weston-super-Mare.

2. „ Dec. 12; fireball, Nottingham, &c.

3. * „ „ 27; large fireball, Somersetshire, &c.

4. * 1864 Jan. 2; star-shower, generally observed in England.

5. „ „ 3, 7, 21; fireballs in England.

6. „ Feb. 1, 9; fireballs, Wimbledon and Hay (S. Wales).

7. „ March 12, 24; great fireballs, Manchester, Hampshire.

8. * „ April 10; star-shower, Hawkhurst.

9. „ ,, 13, 20 (a.m.); star-showers, Hawkhurst.

10. * „ May 14; aerolite, Orgueil, S. France.

11. „ „ 28, June 6, 7, and 10; fireballs at Hay, France, Jer

sey, Bagshot.

12. * ,, July 4 p.m. and 5 a.m.; two large fireballs, England.

13. * „ Any. 6, 9, 10, 16; fireballs, England and the Continent.

14. * „ Sept. 24; great detonating fireball, S. France (day-time).

15. * 1864 Oct. 18; shower of very bright meteors, Hawkhurst.

16. ,, Nov. 2, 11; fireballs, England and France.

17." „ „ 13 A.m.; great star-shower, Malta.

18. * „ „ 20; great fireball, many places in England (detonat

The indications of the diagram having been confirmed in at least eleven remarkable instances during the past year—namely, those marked with an asterisk in the foregoing list—it seems deserving of a trial, if the remainder of its dates will not be confirmed by a much wider sphere of observations.

A few words may not be out of place at the end of my letter to explain the particular language in which this diagram is intended to speak to the eye. The number of the meteors employed is on the average nearly four for every day of the year, which would enclose the whole circle of the year in a band of meteors of even width, if the supply were not suspended at some points of the circle so as to break it and be concentrated upon others. The meteoric curve is, therefore, not a circle, but consists of alternate depressions and prominences. Among the latter many maxima of a minor character nave, for simplicity of representation, been suppressed; but their dates are in each case correctly recorded near the heads of the general maxima. The meteors are more concentrated upon the latter than upon the former half of the year, and there are no indications of any decided reappearance of fireballs at the opposite nodes of their meteoric orbits. The peculiar character of the curve is the abruptness of its oscillations in certain cases, which is correctly represented in the diagram. The 10th April, 18 th October, and zoth November, are remarkably distinguished from the rest in this respect; but no shower of shooting-stars, m two hours, was observed at Hawkhurst on the 20th November (inst ), although star-showers icere observed on each of the two former occasions, viz. the 10th April and the 18th October last; and their radiant points were well determined.

I am, Sir, yours obediently,

ALEXANDER S. HERSCHEL.

Collingwood, Hawkhurst:
Nov. 25, 1864.

P.S.—Dec. 9. Since communicating to you a list of "Dates preferred by firebalh" other observations have come to my knowledge which confirm the dates of the diagram in a more or less remarkable maimer. They are briefly the following:—

* 1864. Aug. 16, A.m.—Very large fireball, and permanent streak. Up. Levantine (St. Gotthard^). The luminous streak assumed a variety of singular shapes before it disappeared.

* 1864. Aug. 26.—Large vari-coloured fireball, red prevailing. Nottingham, S. Wales, &c.

* 1864. Oct. 19.—Large fireball, with enduring streak. Malton, England.

* 1864. Nov. 29.—Large fireball. Paris. 1864. Dec. 4. Bolide, France.

1864. Dec. 9, A.m. Brilliant fireball. Collingwood. Instances might probably be multiplied if the dates of such appearances were more carefully preserved.

P.S.—Dec. i 2. I surmised above, that instances could be easily multiplied of the coincidence of recent fireball dates with the dates noticed in my diagram, if they should be more carefully preserved.

At p. 230 of Capt. Herford's " Stirring Times under Canvass" (8vo. Rd. Bentley, London, 1862), I find a very extraordinary meteor described in plain words as "Donati's Comet!" It was so Drilliant as to inspire terror to the hearts of the rebel Sepoys encamped near Lucknow at the time of the Indian Mutiny, in 1858. Happily, the date of the fireball is here recorded. It is the 25th of September; a date noted for fireballs of the largest class, and frequently seen by day.

THE SUNS SURFACE.

TO THE EDITOR OF THE ASTRONOMICAL REGISTER.

Sir,—In the number of your valuable periodical for November there is a notice of two papers on the Sun by Professor Phillips and myself, which were read at the Meeting of the British Association at Bath. At the close of the paragraph it is said, " Sir Wm. Herschel termed them ' self-luminous clouds;' and the Rev. W. R. Dawes entitled them ' granulations.'"

May I be permitted to correct a mistake in this statement, lest, if it should pass unnoticed, its correctness might be supposed to be acknowledged?

Sir W. Herschel's "self-luminous clouds" are the large masses which, differing considerably in brightness, and being intermingled throughout the sun's surface, produce the coarse mottling which is readily seen with a small telescope—a good 2-inch object-glass, and power 30 or 40 being sufficient. The bright speckled appearance to which I applied the term "granulations" (borrowed from Mr. Stone's appellation " rice-grains," but less restrictive as to form and size) is produced by a minute subdivision of the " self-luminous clouds;" and though under good circumstances these granulations are visible with a very good refractor of moderate size, yet the mottling they produce is extremely fine compared with the effect of the large luminous masses, each of which contains many of them. Sir W. Herschel has well described these granulations. Under date 1792, Sept. 9, he writes: "There is all over the sun a great unevenness in the surface, which has the appearance of a mixture of small points of unequal light;" and he considered them to arise from "a roughness of high and low parts." I first saw these bright points with the excellent 5-foot refractor by Dollond, which I erected at Ormskirk in the spring of 1830; and not having previously heard of them, I thought they were something new, until m the following year I met with Herschel's paper in an interesting little book, entitled Readings in Natural Philosophy, by the Rev. C. C. Clarke. From this I concluded that they were a recognised feature of the sun's surface. For recent observations of them, see my paper in the Monthly Notices of the R.A.S. for May, and the Astronomical Register for June, in the present year.

I remain, Sir, your obedient servant, Hopefield Observatory, 'W. R. DAWES.

Haddenham, Bucks: 1864, Dec. 16.

OF THE SURFACE OF THE SUN. (Second Letter.)

TO THE EDITOR OF THE ASTRONOMICAL REGISTER.

Sir,—In sketching the solitary spot on the sun's disc on the 14th ult, immediately after apparent noon, finding the penumbral outline and radial shadmg (often so clear) considerably confused and indistinct, especially on its eastern side, my attention was drawn to its surrounding neighbourhood, when I was agreeably surprised by the realisation of the elongated very minute lenticular forms, which have been compared to willow-leaves, overlapping the penumbra, and diffused over the whole surface. In making ninety-seven sketches of spots during the last three and a half years, nearly all immediately after taking meridian transits (and not unfrequent observations at other times), I never before or since saw anything beyond the mottled surface, which has been described as parchment, rice-grain, flocculent chemical precipitatelike appearance, &c.; all which have seemed appropriate comparisons at different times—sometimes one, sometimes another—depending, I have supposed, on the state of the air: had long given up all expectation of witnessing this appearance, supposing it far beyond the reach of so small an aperture (4^-inch, p. 100, used), but always visible through large instruments with a fair medium air; but, if so, it seems incredible that it should have escaped the penetrating, eagle eye of so acute an observer as that of our friend W. R. Dawes, even on the supposition of its only very occasional apparition. I have been urged to communicate the foregoing, from an idea not only that it might not be entirely devoid of interest, but that it might possibly be of some use in helping to decide what now appears to have become questionable to some extent—i.e. should the same have been observed at t':e same time, even by a similarly obscure and imperfect observer. Am not aware of anything very peculiar in the then atmospheric condition: I may, however, subjoin a few extracts from my meteorological register of that day:—

At 9b. A.m., 14th of xi. 1864.

Barometer 28-68 in.

Rainfall during preceding 24 hours=0-o8 in. Maximum temperature do. do. . 460 Minimum do. do. do. . 35-5 Hygrometer, dry and wet bulb equal, i.e. 440 Wind S. calm, cloudy, damp m. with short gleams—then fine and mostly sunny; continued still rain vespc

Height of telescope above the mean water-mark at Liverpool= 489ft. 6in.; no building within a mile on meridian south; aspect south, across a valley below.

I am, Sir, yours, &c., Thornton-in-Craven: 17, 12, 1864. T. W.

THE SUN'S DIAMETER.

TO THE EDITOR OF THE ASTRONOMICAL REGISTER. Sir,—The following observations of the sun's apparent diameter I received from Mr. Howlett, F.R. A.S., in October last, who considers them a suitable reply to the objections which Mr, Hickson urges in

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