William F. Denning.

Telescopic Work for Starlight Evenings online

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| 6266. | 62. | 16 54·2 | -29 57 | Stars of 14th-16th mags. In |
| | | | | Scorpio. |
| 6333. | 9. | 17 12·8 | -18 24 | Much compressed group of |
| | | | | 14th mag. stars. Diam. 4′. |
| 6341. | 92. | 17 13·8 | +43 15 | A mass of stars and star-dust.|
| | | | | 7° N, π Herculis. |
| 6402. | 14. | 17 31·8 | - 3 11 | Chiefly stars 15th mag. |
| | | | | Diameter 4′. |
| 6656. | 22. | 18 29·7 | -24 0 | Stars of 11th-15th mags. |
| | | | | In Sagittarius. |
| 6779. | 56. | 19 12·3 | +30 0 | Stars 11th-14th mags. Between |
| | | | | β Cygni and γ Lyræ. |
| 6809. | 55. | 19 33·0 | -31 14 | Fine, large, round cluster of |
| | | | | stars 11th-13th mags. |
| 7078. | 15. | 21 24·7 | +11 41 | Group of stars and star-dus. |
| | | | | Diameter 5′. |
| 7089. | 2. | 21 27·8 | - 1 19 | Exceedingly small stars. |
| | | | | Diameter 5′. |
| 7099. | 30. | 21 34·1 | -23 41 | Stars 12th-16th mags. |
| | | | | Diameter 3′. |
+————————-+——————-+—————————+————————+———————————————————————————————+

III.—NEBULÆ.

+————————-+——————-+——————————————————+———————————————————————————————+
| | | Position, 1890. | |
| No. | No. +————————-+————————+ |
| N.G.C., | M., | | | Description. |
| 1888. | 1781. | R.A. | Dec. | |
+————————-+——————-+—————————+————————+———————————————————————————————+
| | | | | |
| | | h m | ° ′ | |
| 185. | | 0 32·9 | +47 44 | Very large; pretty bright. |
| | | | | Resolvable into stars. |
| 224. | 31. | 0 36·7 | +40 40 | Great nebula in Andromeda. |
| | | | | |
| 253. | | 0 42·2 | -25 54 | Very, very large and bright. |
| | | | | 24′ by 3′. |
| 598. | 33. | 1 27·6 | +29 57·1| Exceedingly bright and large.|
| | | | | Nucleus. |
| 650. | 76. | 1 35·4 | +51 1 | Very bright double nebula. |
| | | | | |
| 1365. | | 3 29·4 | -36 30 | Very bright and large. |
| | | | | Elliptical. |
| 1501. | | 3 57·5 | +60 37 | Pretty bright planetary |
| | | | | nebula. Diam. 1′. |
| 1514. | | 4 2·4 | +30 29 | Star of 9th mag. in nebula 3′ |
| | | | | diameter. |
| 1952. | 1. | 5 27·9 | +21 56 | Great Crab Nebula, near |
| | | | | ζ Tauri. Stars. |
| 1976. | 42. | 5 29·9 | - 5 28 | Great nebula involving θ |
| | | | | Orionis. |
| 1990. | | 5 30·6 | - 1 16 | Star (ε Orionis) involved in |
| | | | | nebulosity. |
| 2070. | | 5 39·5 | -69 9 | Visible to naked eye. Great |
| | | | | “looped” nebula. |
| 2392. | | 7 22·7 | +21 8 | Nebulous star of 9th mag. |
| | | | | |
| 2403. | | 7 26·2 | +65 50 | Very large and bright. |
| | | | | Elliptical. |
| 2655. | | 8 41·2 | +78 38 | Very bright. Condensed in the |
| | | | | middle. |
| 2681. | | 8 45·6 | +51 44 | Very large and bright. |
| | | | | Centre = star 10th mag. |
| 2683. | | 8 45·9 | +33 51 | Very large and bright. |
| | | | | Elliptical. |
| 2841. | | 9 14·4 | +51 26 | Very large and bright. |
| | | | | Centre = star 10th mag. |
| 2903. | | 9 25·9 | +22 0 | Large, elliptical, double |
| | | | | nebula. |
| 3031. | 81. | 9 46·5 | +69 35 | Exceedingly bright and large. |
| | | | | Elliptical. |
| 3034. | 82. | 9 46·7 | +70 13 | A bright ray. In field with |
| | | | | preceding. |
| 3242. | | 10 19·5 | -18 5 | Bright planetary nebula. |
| | | | | Diameter 45″. Blue. |
| 3372. | | 10 40·8 | -59 6 | Great nebula surrounding |
| | | | | ζ Argûs. |
| 3556. | | 11 5·4 | +56 16 | Large, rather bright. |
| | | | | Elliptical. |
| 3587. | 97. | 11 8·4 | +55 37 | Fine planetary nebula. Diam. |
| | | | | 3′.Near β Ursæ Majoris. |
| 3623. | 65. | 11 13·2 | +13 42 | Large, bright, elliptical. |
| | | | | Near following one. |
| 3627. | 66. | 11 14·5 | +13 36 | Large elliptical nebula. Near |
| | | | | β Leonis. |
| 4254. | 99. | 12 13·3 | +15 2 | Very fine 3-branched spiral |
| | | | | nebula. |
| 4321. | 100. | 12 17·4 | +16 26 | Very large 2-branched spiral |
| | | | | nebula. |
| 4382. | 85. | 12 19·9 | +18 48 | Very bright; pretty large. |
| | | | | Round. |
| 4472. | 49. | 12 24·2 | + 8 37 | Bright; round. Resolvable into|
| | | | | stars. |
| 4486. | 87. | 12 25·3 | +13 0 | Large; round. Bright centre. |
| | | | | Third of three. |
| 4565. | | 12 30·9 | +26 36 | A ray of bright nebulosity E. |
| | | | | of Coma. |
| 4736. | 94. | 12 45·7 | +41 43 | Large and bright. Nucleus. |
| | | | | Resolvable. |
| 5128. | | 13 19·0 } -42 27 | Very large and bright. |
| | | | | Elliptical. Bifid. |
| 5194. | 51. | 13 25·2 | +47 46 | Great spiral nebula near |
| | | | | ζ Ursæ Maj. |
| 5236. | 83. | 13 30·8 | +29 18 | Fine object. 3-branched |
| | | | | spiral. |
| 5367. | | 13 51·1 | -39 27 | Very large and bright. |
| | | | | Condensed in the middle. |
| 5907. | | 15 13·0 | +56 44 | Large, elliptical. Another |
| | | | | very close to it. |
| 6369. | | 17 22·6 | -23 40 | Pretty bright, small |
| | | | | ring-nebula. |
| 6514. | 20. | 17 55·7 | -23 1 | Bright; large. Trifid. Double |
| | | | | star involved. |
| 6523. | 8. | 17 56·9 | -24 23 | Bright, with loose cluster of |
| | | | | stars. |
| 6618. | 17. | 18 14·4 | -16 13 | Bright and extremely large. |
| | | | | 2-hooked. |
| 6720. | 57. | 18 49·5 | +32 54 | Ring-nebula between β and |
| | | | | γ Lyræ. |
| 6826. | | 19 41·8 | +50 16 | Pretty large and bright |
| | | | | planetary nebula. |
| 6853. | 27. | 19 54·9 | +22 25 | The “Dumb-bell” Nebula. Fine |
| | | | | object. |
| 6960. | | 20 41·1 | +30 19 | Large and bright, κ Cygni |
| | | | | involved. |
| 7009. | | 20 58·2 | -11 48 | Very bright, small, planetary |
| | | | | nebula. Elliptical. |
| 7662. | | 23 20·6 | +41 56 | Very bright, pretty small, |
| | | | | planetary or ring-nebula. |
+————————-+——————-+——————————————————+———————————————————————————————+


FOOTNOTES:

[55] Sir W. Herschel at first entertained this view, finding that with
every increase of telescopic power more nebulæ were resolved. But in
1791 he said, “perhaps it has been too hastily surmised that all milky
nebulosity is owing to starlight only.” Lacaille had remarked in 1755
that “it is not certain the whiteness of parts of the Milky Way is
caused by clusters of stars more closely packed together than in other
parts of the heavens.”

[56] This is exclusive of 47 new nebulæ discovered by Prof. Safford,
which form the appendix to the catalogue.

[57] Chambers says only four examples are known, but this is erroneous,
as Lord Rosse’s telescope has added five ring-nebulæ to the four
previously catalogued.

[58] Some of the nebulæ in Messier’s list were discovered by Mechain at
Paris, who, like Messier, earned celebrity by his cometary discoveries.
He was born at Laon in 1744, and died at Valencia in 1805.

[59] O. Struve had expressed views identical with these in 1857 (see
‘Monthly Notices,’ vol. xvii. p. 230).

[60] Humboldt says this “name is evidently derived from the voyage of
Magellan, although he was not the first who observed them.”

[61] I have selected the various objects in these lists from the New
General Catalogue.

[62] These forms are more numerous than the annular nebulæ. They often
exhibit a blue colour, and the spectroscope shows them to consist of
gas.




NOTES AND ADDITIONS.


LARGE AND SMALL TELESCOPES.

P. 19.—With reference to mountainous sites for large instruments,
a remark in Sir Isaac Newton’s ‘Opticks’ (1730) may be
quoted:—“Telescopes ... cannot be formed so as to take away that
confusion of rays which arises from the tremors of the atmosphere. The
only remedy is a most serene and quiet air, such as may perhaps be
found on the tops of the highest mountains above the grosser clouds.”

P. 27.—Lieut. Winterhalter, of the United States Navy, recently
visited a large number of European observatories, and in describing
that of Nice says:—“M. Perrotin declares that two hours’ work with
a large instrument is as fatiguing as eight with a small one, the
labour involved increasing in proportion to the cube of the aperture,
the chances of seeing decreasing in the same ratio, while it can
hardly be said that the advantages increase in like proportion.” The
Nice Observatory, and its splendid instruments (including a 30-inch
refractor), are due to the munificence of M. Bischoffsheim, who has
expended about five million francs upon them.

P. 36.—The large refractor to be erected on Wilson’s Peak of the Sierra
Madre range of mountains, in Southern California, is to be 40 inches in
diameter. The rough unground disks of glass are already in the hands of
the Clarkes, of Cambridgeport, Mass. It is estimated that the complete
object-glass and cell will cost something like $65,000, and the focal
length of the instrument will be about 58 feet.


THE SUN.

P. 100.—The last minimum of sun-spot frequency appears to have occurred
at the middle of 1889. Conspicuous spots were very rare in the first
half of 1890, but some fine groups were presented in the last half of
the year. On Aug. 31 I saw a group extending over 113,000 miles in
length, and on Nov. 27 there was another, which measured 123,700 miles.

P. 111.—Thompson’s cardboard disks have been favourably spoken of as
enabling observers to determine the positions of spots at any season of
the year.


MERCURY.

P. 137.—At the meeting of the British Astronomical Association on
Nov. 26, 1890, Mr. G. F. Chambers expressed his firm belief in the
existence of an intra-Mercurial planet. The President (Capt. W. Noble)
in his inaugural address pointed out the desirability of effecting
further observations, both of Mercury and Venus, with a view to
redetermine their rotation-periods. He justly remarked that moderately
small instruments might be fittingly employed in the work, and that
Schiaparelli’s deductions (mentioned on pp. 142 and 149) ought to be
accepted with extreme reserve pending their verification.


MARS.

P. 160.—Prof. W. H. Pickering observed some of the canals on Mars in
1890 with a 12-inch refractor, but was not able to double any of them.
He says that, in examining these objects, the power employed should
not “exceed one or two hundred.” This is quite contrary to the advice
of others, who recommend high magnifiers; and perhaps it accounts for
Prof. Pickering’s failure in recognizing the duple canals.

With the great 36-inch refractor Mr. Keeler saw, on July 5 and 6, 1890,
some curious white spots on the edges of the gibbous limb of Mars,
something similar to those visible on the unilluminated part of the
lunar disk. The canals were observed as feeble diffused bands. The two
satellites were seen by a lady visitor, though previously unaware of
their existence.

P. 161.—The method of deriving the rotation-period of Mars is
exemplified by Mr. Proctor in the ‘Monthly Notices,’ vol. xxviii. p.
38. An interesting paper, “On the Determination of the Rotation-Period
of Jupiter in 1835,” will be found in the ‘Memoirs,’ vol. ix.


PLANETOIDS.

P. 167.—The 308th planetoid was discovered by Charlois on March 5, 1891.


JUPITER.

P. 170.—Dupret, in Algiers, saw Jupiter with the naked eye on Sept. 26,
1890, and following days, twenty minutes before sunset.

P. 191.—M. Guillaume, during a recent transit of the shadow of
Jupiter’s second satellite, observed a duplicate shadow, fainter than
the ordinary one, which partly covered its southern side.


COMETS.

P. 250.—On Nov. 16, 1890, Dr. Spitaler, while looking for Zona’s Comet
with the 27-inch refractor of the Vienna Observatory, discovered a new
and very faint comet only 23′ distant from the object of his search.
That two of these bodies should be found almost simultaneously and so
near together must be regarded as a very singular coincidence.


METEORS.

P. 261.—Mr. Proctor held the view that certain meteorites may have
originally been ejected from the Sun. A recent writer thus summarizes
our knowledge of them:—“That they are independent bodies, moving in
orbits of their own in space; that these dark bodies are abundant in
the interplanetary spaces; that those within the near range of solar
or planetary attraction move with great velocity; that many swarms of
them follow well-known orbits; and that, in general, their origin is
undoubtedly the same as that of other celestial bodies” (‘Sidereal
Messenger,’ June 1890, p. 284).

P. 267.—On May 2, 1890, a brilliant fireball, leaving a long train of
fire and smoke, and exploding with a noise like thunder, was seen at
many places in Northern Iowa, Minnesota, U.S.A. Some fragments of the
meteor fell on a farm a few miles from the south line of Minnesota.
The largest piece was sold by auction for $100, but it soon transpired
that the person who sold it was only the lessee and not the owner
of the ground on which the meteor fell. The aerial visitor and its
purchase-money were therefore peremptorily seized by legal authorities,
pending the decision of a Court of Justice as to the rightful ownership.

P. 267.—On December 14, 1890, at 9^h 42^m a large fireball of dazzling
lustre, and giving a report like thunder, was widely observed in the
southern parts of England. At the end-point the fireball appears to
have been only 8 miles in height, and over a point near Brentwood, in
Essex.


THE STARS.

P. 309.—Prof. Chandler, of Cambridge, Mass., estimates that the total
number of variable stars visible with a common field-glass is about
2000, but with a large telescope there are probably hundreds of
thousands within reach. He further states that quite five sixths of the
variable stars are reddish in colour, and that the redness is usually a
function of the length of the period of variation. The redder the star
the longer its period.

P. 312.—In a recent communication to the Academy of Sciences, M.
Lescarbault (the alleged discoverer of Vulcan in 1859) announced that
on the night of January 11, 1891, he discovered a bright body in Leo
which he could not identify in any star-map, and hence concluded it
to be a new star, or one suddenly increased in brilliancy. The “new
star,” however, subsequently turned out to be the planet Saturn! This
ridiculous mistake (so easily avoidable with a little care) will
naturally divest the supposed discovery of Vulcan of the importance
attached to it by some writers, for M. Lescarbault obviously lacks the
experience and caution necessary to command credit.


NEBULÆ AND CLUSTERS OF STARS.

P. 327.—Mr. Roberts, from a comparison of his photographs, has found
distinct evidence of variability in the nucleus of the great nebula
in Andromeda. In some of the photographs the nucleus is shown to
be stellar, while in others there is no trace of this. Mr. Roberts
remarks:—“We may reasonably infer that the nucleus of the nebula is
variable, and that it will be practicable to study the character of
the variability without the necessity of giving long exposures of the
plates.” The period of the variation has now to be determined, and it
is advisable that telescopic observations of the nucleus should be
made with the view of confirming the photographic results. It would be
premature to regard the changes as demonstrated before they have been
submitted to thorough investigation.

P. 327.—In the _Comptes Rendus_ for March 2, 1891, M. Bigourdan has
a paper on the variability of the nebula N.G.C. 1186, situated near
Algol. This nebula was discovered by Sir W. Herschel in 1785, and
though Sir J. Herschel re-observed it in 1831, Lord Rosse looked for
it without success in 1854 and 1864. On Nov. 8, 1863, D’Arrest failed
to detect the nebula, though he searched for it with assiduity at a
time when the sky was very favourable. He was led to conclude that
the object did not exist. M. Bigourdan finds that the nebula is again
visible in the position indicated by the two Herschels, viz. R.A. 2^h
54^m 20^s, Dec. +42° 10′, he having observed it on Jan. 31 and Feb. 26,
1891. It is difficult to believe that this object could have escaped
the scrutiny of Lord Rosse and D’Arrest in 1854, 1863, and 1864; hence
the variation is probably real. The nebula may be easily found, as it
is very near the binary B.D. +42° (1123 G.C.), the position of which
for 1891 is R.A. 2^h 58^m 6^s, Dec. +42° 29’ (‘Nature,’ March 12, 1891).

P. 329.—While examining the Pleiades on the night of November 14,
1890, Mr. Barnard discovered a new and considerably bright, round,
cometary nebula 36″ S. and 9″ following Merope. The reason why this
nebula has not been detected by photography is because it is so near
Merope that the over-exposed light from the star obliterates it. But
it is certainly very strange that the object alluded to has never
been telescopically discovered before; for the Pleiades have been
scrutinized repeatedly with all sorts of telescopes, and particularly
since Tempel announced his discovery of a large faint nebula involving
Merope in 1859. Mr. Barnard says the new nebula is 30″ in diameter,
and that it is visible in a 12-inch refractor when Merope is hidden
with a wire.




INDEX.


Action in Sun-spots, Cyclonic, 108.

Active volcanoes on the Moon, 120.

Adams theoretically discovers Neptune, 222.

Advantage of Equatoreals, 54.

Aerolites, 264.

Air and water on the Moon, Absence of, 115.

Algol, 310.

Alleged satellite of Venus, 152.

Almanacks, 83.

Alphabet, Greek, 287.

Alpine Valley, 127.

Altitudes of markings on Jupiter, 185.

Amateur’s first view of Mercury, 139.

Ancient ideas concerning meteors, 260.

Andromeda, Great Nebula in, 334.

Andromedes, 276.

Angles of Position, Measurement of, 291, 306.

Announcement of a new comet, 244.

Annual rate of cometary discoveries, 255.

Antares, 309.

Anthelme, Discoverer of a new star in 1670, 313.

Apennines, 132.

Aperture and Power required for Comet-seeking, 252.

Apparitions, Meteoric, 261.

Appearance of Comets, 228.

—— of Mars, 155.

Aquarids, 275.

Archimedes, 127.

Argelander’s magnitudes of stars, 294.

Aristarchus, 120.

Ascertaining positions of Comets, 257.

Aspect of the rings of Saturn, 204.

Atmosphere of Jupiter, 177.

—— of Mars, 161.

—— of Mercury, 139.

—— of Venus, 151.

Atmospheric undulations, 29.

Attractions of Telescopic work, 85.

Auwers, Discoverer of a new star in 1860, 314.


Bacon, Roger, Early hints on refracted rays, 3.

Barnard, His cometary discoveries, 255.

—— observes Brooks’s multiple Comet, 239.

—— observes new stars in the Trapezium, 319.

—— observes a new nebula in the Pleiades, 351.

Beauty and brilliancy of Venus, 145,

Belts of Sun-spots, 104,

—— on Jupiter, 172.

—— on Saturn, 198.

—— on Uranus, 218.

Berthon’s dynamometer, 50.

Biela’s Comet, 238.

Bigourdan observes a variable Nebula, 351.

Binary Stars, 300.

Birmingham discovers a new star in 1866, 314.

Bond, G. P., discovers Crape-ring of Saturn, 202.

Brahe’s, Tycho, new star of 1572, 312.

Bright objects near the Sun, 107.

Brightness and position of Jupiter, 170.

Brooks on Comet-seeking, 253.

—— on Occultation of Jupiter, 187.

—— on Shower of telescopic Meteors, 272, 274.

Brooks’s double Comet of 1889, 239.

Brorsen’s Comet, 239.

Browning and reflecting-telescopes, 60.

Brunowski discovers a new star, 313.

Burnham, Discoverer of double Stars, 31, 320.

—— discovers a group of 18 new nebulæ, 341.

——, Measures of the companion to Sirius, 307.

—— on the inutility of “stops,” 58.


Calver compares light of reflectors and refractors, 37.

——, Maker of glass specula, 16, 17.

Canal-shaped markings on Mars, 159.

Canis Majoris α, 307.


Cassegrain’s reflecting-telescope, 10.

Cassini, Diameter of his object-glasses, 9.

—— discovers four satellites and the divided ring of Saturn, 9.

——, Observations of Jupiter, 172.

——, —— of Saturn, 198.

——, —— of Venus, 147.

Celestial Globe, 63.

Centauri α, Diameter and distance, 299.

Ceres, 168.

Chambers on Coloured Stars, 316.

—— on the intra-Mercurial Planet, 348.

Chandler on Variable Stars, 350.



Online LibraryWilliam F. DenningTelescopic Work for Starlight Evenings → online text (page 30 of 32)