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To a gentleman of such great experience and knowledge as Mr. Dawes, small errors are great faults; but I question very much whether Mr. Darby ever dreamed of his book being of the slightest assistance to one whose library must be already full of works of far greater importance to the professional astronomer than this little handbook.
Yours truly, Manchester: May 5, 1865.
TO THE EDITOR OF THE ASTRONOMICAL REGISTER.
Sir,- In your May number of the Register you publish a notice of some errata in the Astronomical Observer, by the Rev. W. R. Dawes. I beg to express my obligations to Mr. Dawes for his corrections, although I think he attaches undue importance to them; for, with some two or three exceptions, they are either typographical errors, or trifling mistakes which cannot affect the general character of the book.
1. Mr. Dawes states that “the example given in the Introduction of converting sidereal time at Manchester into Greenwich mean solar time is erroneous in its method.” The method is based on the formulæ of the Nautical Almanac; a slight error has arisen from not embracing the whole of the decimal figures, but it is sufficiently accurate for the amateur. This method has been in use for some years at three observatories in Manchester.
2. “In the list (Introd. xxv.) of test objects, the epoch of the places is 1865; but the epoch of distance in the last column is very different; and, consequently, in several of the binary stars in the lists the distances given are very erroneous.” The tables in question are headed " from Smyth's Cycle of Celestial Objects." The only change I felt at liberty to make was to bring up the places to 1865, assuming that there could be no mistake as to Smyth's well-known epoch of 1840.
3. “ The omission of the epoch of the binary stars is a serious fault, and pervades the whole book.” The number of binary stars given is 20. In a few exceptions " Mr. Dawes admits that the epoch has been given: I do not see how the omission of the epoch from the remaining 12 or 15 binary stars could possibly affect the whole book !
4. “P. 5.--Antin. 185 p. xix. and 186. The description of these objects is almost entirely erroneous." The whole description is taken from “Smyth's Cycle," perhaps the most accurate astronomical work extant.
5. 55 Cassiop. “Both the R. A. and Dec. of this star are given erroneously.” Mr. Dawes should have looked in the list of errata, where he would have found both this and the next error he notices, 66 i (44) Bootis," corrected. , 6. P.60.-" 215 Libre [? 15 Libræ? This star is not double at all. The whole description is a mistake; as is also the remark that the R.A. is erroneously given in Mr. Bishop's Catalogue. Mr. Darby has confounded it with 51 Libræ . It is strange that Flamsteed's obvious mistake should have been adopted at all. Argelander, with his usual accuracy, has restored the star to Scorpio (in 1840), and omitted 51 Libræ.” The British Association Catalogue distinguishes those stars. 51 Libræ, though given as & Libræ by Struve, Sir John Herschel, Bishop, and Dawes, is not lettered & Libræ on any of the globes or star-charts in my possession. According to Admiral Smyth, Argelander, and even Mr. Dawes, & Libræ is a misnomer for 51 Libræ, and the star is properly & Scorpii. Baily does not, that I am aware, give 51 Libræ as one of the errors of either Bayer or Flamsteed. Malby's last globe, the most correct sidereal chart ever published, gives ? Libræ as Duplex.
7. “The object and plan of the body of the work (the Astronomical Observer) are excellent, being, in fact, an extension of the sidereal portion of the Rev. T. W. Webb's Celestial Objects; and if it were but comparable to that valuable little volume in point of accuracy, it would be in that department proportionably more useful." I regret much that Mr. Dawes has gone out of his way to contrast Mr. Webb's book and mine. My catalogue, I assure him, is not in any sense an extension of Mr. Webb’s; it was in MS., and in its present form, though not the same in compass, in 1859, before the publication of Mr. Webb's book. It is true that I have gleaned several objects and notices from Mr. Webb's excellent work, but I believe they are all honestly acknowledged. It is true also that in one particular I have followed Mr. Webb's example, in " omitting, with few exceptions, the epoch of the distances of the binary stars; " yet, from this "serious fault” (mea maxima culpa), Mr. Dawes absolves Mr. Webb, and condemns me. “O, upright judge !”
I may observe that the whole design of my catalogue is very different from that of Mr. Webb, as will be apparent from "a mere cursory inspection.” Mr. Webb (page 153) designed his catalogue for the regular astronomer-the possessor of an equatorial telescope. My catalogue, as the Introduction states (xii.), is designed to accommodate as far as possible the major part of the objects to the nonequatorial telescope, and to provide a help to observation for the now very numerous and increasing class of amateur astronomers.
W. A. DÁRBY, M.A. St. Luke's Rectory, Manchester.
[Further correspondence on this subject must be inserted in the Appendix.-Ed.]
OCCULTATIONS OBSERVED AT MENTONE LAST WINTER, by D. A. FREEMAN, Esq.-On October 9, 1864, I observed the occultation of B Capricorni. In the 48 minutes preceding, three other stars were occulted, including 79 Capricorni. They were all by the dark part of the moon. On December 3, at 5.10 P.M. L. M. T., on first turning the telescope on the moon, I observed a bright flickering light on the dark side ; in a few seconds it disappeared suddenly. It was, I believe, 187 Capricorni, 7th m. On December 5, at gh. gm. P.M. L. M. T., I observed the occultation of x Aquarii on the dark side. On March 3. last, at 11.7 L. M. T., I observed the occultation of in the same field there was a fine double star, which was, I presume, 177 and 179 Tauri. On April 6, at 8.27.30 P.M. L. M. T., I observed the occultation of 16 Sextantis; on April 12, at 11.17.20 L. M. T., at the bright side of the moon, that of 8 Libræ; and at 11.30.20 L. M. T., that of a Libræ ; and on May 2, at 8.36 L. M. T., that of k Cancri. The disappearance of all appeared to me instantaneous. Telescope used, a 43-in. refractor, by Messrs. Cooke & Sons.
3 Tauri. 40 or 50 seconds sooner there was occulted a star of about the 8th m., a little north of 83, and n. f. at about 20' or 25' from ;3; and
THE PLANETS FOR JULY.
Mercury passes from Gemini into Leo in July, and may be observed in the evening at the end of the month. It is very close to Regulus on the afternoon of the 27th.
ist R.A. 6 40 18 Dec. N. 24 25 Diameter sko 3180 » 10 21 17
612 Venus attains its greatest westerly elongation on the 17th, remaining in Taurus. It is an excellent object for the transit instrument in the morning, passing the meridian a few minutes before 9 A.M. each day during the month.
ist Ř.A. 3 34 23 Dec. N. 15 32 Diameter 27":6 3180 25 30 58
9 20 234 , 2010 Illuminated portion of the disc of Venus=0.488. Mars can now be seen only with difficulty, owing to its near approach to the sun. It is near Regulus on the 13th, and remains in Leo during the month.
ist R.A. 9 41 16 Dec. N. 15 8 3180 . 10 51 22 5 8 18
Nluminated portion of the disc of Mars=0.963. Jupiter, allowing for its low altitude, is well visible in the evenings, remaining in the constellation Ophiuchus. It rises about a quarter to 7 in the evening at the beginning, and about half-past 4 at the end of the month, remaining above the horizon eight hours only.
ist R.A. 17 25 47 Dec. S. 22:50 Diameter 42''.8 3180 , 17 14 35 , 22 45
, 401.8 Saturn sets shortly after midnight at the beginning, and about half-past 10 at the end of the month.
ist R.A. 13 31 15 Dec. S. 6 484 Diameter 16'•o
318t 13 34 40 2 7 17 Dimensions of ring-Outer major axis, 39'':0; Outer minor axis, 9'5.
THE MINOR PLANETS. The following are the minor planets which will arrive at opposition this month. Full particulars will be found in the Supplement to the Nautical Almanac for 1868:
Magnitude . Right Ascension Declination Hestia ... ... ... 11'0 July 10... ... 20 27 | 1 S. 15 22 Asia ... ... ... ... 10'4 '
... 18 30
II 25 Feronia ... ... ...
This celebrated object is now on its return to these parts of space. Though its perihelion passage does not take place till next year, astronomers will at an early date be called upon to direct their telescopes in search of it. The ephemeris, which will appear month by month in the Astronomical Register, has been computed by Dr. Michez.
For Greenwich Mean Noon. 1865 R. A. Decl. 1 1865 R. A. Decl.
h. m. S. July 24 ....0 18 37 ... +18 408 July 28 ... O 20 9 ... +18 16:0
25 ... O 19 0 ... +18 49•6 29 ... O 20 32 ... +19 2497 26 ... O 19 23 ... +18 58.4
30 ... O 20 50 ... +19 33'2 27 ... O 19 46 ... +18 7.2 31 ... 21 8 ...+19 417
COMET I. OF 1865.
The following elements are by M. Moesta, of Santiago :
Perihelion passage 1865, Jan. 14'3 G.M.T.
Longitude of Perihelion = 142 58
= 87 42
Retrograde. They do not differ much from Mr. Hind's, published in our last number.
G. F. C.