The Hartwell Experiment.
We tried an experiment on chromatic personal equation, in its simplest form, at Hartwell, on a fine evening, the second July, 1829. Having repaired a stone pedestal in front of the south portico of the house, on which was placed a Gregorian telescope of 5½ inches aperture, a party of visitors, consisting of six ladies and five gentlemen, were invited to gaze upon the double-star Cor Caroli; and they [*50] were each to tell me - sotto voce to prevent bias - what they deemed the respective colours of he components to be. The first who stepped out by request, was my good friend the late Rev. Mr. Pawsey - more addicted to heraldry than to astronomy - who, after a very momentary snatch, flatly declared that he “could make out nothing particular”: but the other spectators were a little more attentive to the plan proposed, and their respective impressions were thus noted down in the large Hartwell Album:-
Miss Tyndall | A. Pale White | B. Violet tint |
Mrs. Rush | A. Yellowish cast | B. Deadish purple |
Miss Honor | A. Yellowish | B. Lilac |
Miss Charlotte | A. Light dingy yellow | B. Lilac |
Miss Emily | A. White | B. Plum colour |
Miss Mary Anne | A. Paleish yellow | B. Blue |
Mr. Rose | A. Cream colour | B. Violet cream |
Mr. B. Smith | A. Pale tint | B. Darker blue |
Dr. Lee | A. Whitish | B. Light Purple |
Capt. Smyth | A. White | B. Plum-coloured purple |
Now, whatever may be said about instrumental means, tendency of metallic mirrors, weather influence, atmospheric light, or the object’s position as to meridian, it is clearly obvious that every condition was common to the whole party, and we doubtlessly all meant the same hues. It must be admitted, however, that the stars were new to most of the spectators, and, though some of the eyes were surpassingly bright, they had never been drilled among the celestials. Further observation, with an achromatic instrument, led me to record Cor Caroli in the Cycle for 1837, A flushed white, and B pale lilac; but, as Sestini found them to be yellow and blue in 1844, I again probed them in 1850, when A struck me as full white and B very pale but slightly ruddy under that paleness. From the lightness of the tints, this object offers less distinctness than deeper-coloured stars ; insomuch that in 1830 Herschel said - “With all attention I could perceive no contrast of colours;” yet, at my last [*51] inspection in 1855, three observers were unanimous that A appeared to be a pale reddish white, and B lilac, under a magnifying power of 240, and a fair sky. All this shows the urgent necessity of a chromatic scale being drawn up for general adoption; and that, as yet, we are only on the threshold of a very beautiful department of knowledge.
Mistaken notion.
Many persons may think that a mere glance at colours is enough to impress them at once on the memory, and that, without any practice at that sort of remembrance, they can keep any tint in their mind for a length of time; but a more erroneous idea was never entertained. To these unhappy persons greens are greens, and blues blues; for they heave never entered the magical region of colours, whereby a whole world of intellectual enjoyment is for ever closed against them. Bring them to the proof of their boasted powers; show them any portion of a landscape; and then place colours before them, and make them put down the various tints from memory, but this a week or two after the scene was witnessed. If hardy enough to attempt the task, every one of their tints will be found in error, and they will only put down one where nature had fifty. Even the painters confess, that, though colour may be a low branch of their art, yet it is the most difficult. Just look at the walls of the Royal Academy and see how rarely is a good colourist to be met with, and, when he is, how the initiated will gloat over the matchless and magic variety and mellowness of tints, while the uninitiated can see barely more than one, and that to them not noticeably different from the world of common-places beside it. Only look, too, at the characteristics of those painters who draw from nature, but do not colour also from her; who make their sketches in the open air with pencil or sepia, and fancy colouring to be so simple and so easily remembered, that they may do that afterwards comfortably at their home. Such works are detected wherever they are seen, by the poverty of tights, and by the uniformly monotonous colours that are always employed in the same manner. The human mind cannot invent to any extent, but can merely [*52] put together in a novel manner materials collected from the external world. Hence such materials in colouring can only be impressed on the memory by actual pains-taking and labourious copying and working from nature, by making the tints and applying them in imitation of her. By such training, this branch of memory may be strengthened as well as any other; for we find that the works of artists who adopt this method are always superior in their colouring to those of ethers, even when they paint from retentive memory or imagination. And one of the best colourists that we have ever had in landscape-painting was so impressed with the importance of cultivating the memory in this manner, that he used, even in the days of his prosperity and highest prices of his works, to spend much time in the open all- making studies in oil, and then, as soon as they were made, tore them up; so that, as the followers of Cortez saw the necessity of conquering when their commander burnt the ships in which they might have made an inglorious retreat, and exerted themselves accordingly, - in the same way, not being able to refer, when painting a picture at home, to the sketch made in the open air, he felt himself necessarily obliged to tax his powers of memory, and make them exert themselves to the very utmost.
Signor G. Lusieri.
In the early part of this century, it was my good fortune while in Athens to make the acquaintance of the late Signor Gianbattista Lusicri, the eminent landscape-painter engaged by Lord Elgin to work in Greece. This philosophical artist showed me a series of views, proving his gradual improvement through twenty years, by making Nature his model throughout; and he restricted himself, moreover, to the same hour of the day for colour; so that some pictures which he was unable to complete before a change of weather, he reserved tilt the same season of the following year. Hence in great measure arose the perfection of his pencil.
Spectral lines.
The second, or instrumental, method of determining colour,
need not be entered upon at much length here, as mere
amateurs are not very likely to practise it; and would be
[*53] working at a great
disadvantage compared with any instrument in a public
observatory specially devoted to this object-
Brightness is everything under such appliance, and this
must be commanded both by elevating the telescope into a
high region of the atmosphere, and by adopting the largest
possible size of aperture; for, not only must photometrical
determinations of the lucidity of different sections of the
spectra of stars formed by prisms be made, but the black
lines in the spectra of each star must also be carefully
examined into, as all the transcendent intelligibility of
modern optics depends on them. Still the task appears to be
equally prolix and toilsome; and, moreover, spectrum
explanations are much more fatiguing to the eye than
ordinary telescopic work while it is only on the finest
nights that the lines in the stellar spectra are steady
enough for measurement. Indeed the difficulties of
observation are now so complex, that the complete scrutiny
of the spectrum of a single star may probably be the work
of some years. [10]
Wollaston and Frauenhofer.
It is under no depressing view of the effects of progress that I perceive, however anticipations may be indulged in, the alliance between Astronomy and Chemistry is not yet definitively ratified so that at present it is rather perplexing to speculate upon the ultimate results of the connection. Suffice it here to note, it is to my late eminent friend Wollaston that we owe the discovery of the existence of a peculiarity in solar light, which reveals the deficient rays causing the black lines of the spectrum: and this was followed quite independently by the marvellous measures of them by Frauenhofer and of Munich, whose accurate determinations of their distances now form standard points of reference for apportioning the refractive powers of different medico on the rays of light. These opera-lions opened out away for the masterly metallic investigations of Kirchhoff and Bunsen. Such skilful and well-conducted researches [*54] are pregnant with the best augury; and the elaboration of successive variations of them must infallibly aid our future advance in the knowledge of STELLAR PHYSICS.
Advantages of instrumental method.
There is still, however, much to achieve before full reliance can be indulged in, as well respecting drilling the eye as the manufacture and use of its apparatus, and the subsequent delicate manipulation. When genius and perseverance shall have brought these conditions to bear in concentrated practice, then will this instrumental method of reducing colour to brightness and place prove invaluable; because - in addition to the exactness of the numerical determination of which it will then be capable - it would further overcome a most serious source of error - one which has barely been touched upon in all that has gone before in this our lucubration, and may affect to its fullest extent the method of the “senses,” namely, chromatic personal equation. In fine, it seems destined to become another means of augmenting the debt which pure Astronomy ewes to the powers of practical observation - which is the basis of all we know in the argument.
Proposed diagram of colour.
The instrumental desiderata above alluded to are mostly, as
yet, irreducible to general practice, especially upon
minute or dim objects; and, therefore, until certain
difficulties shall be overcome, the amateur may still
render good service to the cause, by noticing the stellar
hues according to the scheme of colours submitted to him on
the chromatic diagram appended. Where the mental impression
is not quite adequately represented by these tints, it can
be modified by an expressive adjective, as blueish green,
brownish yellow, and the like; but, in pronouncing upon
very delicate distinctions, the observer must keep in mind
that all colours are accompanied by their accidental or
opposite tinctures, or those which depend on the affections
of the eye, rather than on the light itself - and, when the
direct and accidental colours are of the same intensity,
the accidental is then called complementary, because
completing the series with the direct hue.
The very numerous shades from white to pale yellow are so
[*55] unfit for representation
and lamplight reference, that they are omitted in the
annexed form; but the careful observer may readily estimate
the intensity of almost colourless bodies according to the
following order - Creamy white 1, Silvery white 2, Pearl
white 3, and Pale white 4.
Notwithstanding the amount of obstacles that I have
mustered up, they are not insuperable to resolution ; for,
as in mundane affairs, the word impossible ought to meet
with no encouragement in scientific emprise. A specimen of
the advantages of a more exact method than that which has
hitherto obtained among us, may be here given, as showing
that the glow ascribed can readily be consulted, which the
mere guessing cannot. Indeed, if memory is to be trusted so
for, some notations on the old system may be contrasted
with our proposed plan, thus -
STAR | CYCLE | DIAGRAM | ||
51 Piscium | A. Pearl White | B. Lilac tint | A. White 3 | B. Purple 3 |
γ Andromedæ | A. Orange colour | B. Emerald green | A. Orange 2 | B. Bluish green 3 |
40 Persei | A. Pale white | B. Ash-coloured | A. White | B. Blue 4 |
225 P. Aurigæ | A. Creamy white | B. Pale grey | A. White 1 | B. Blue 4 |
δ? Hydræ | A. Light topaz | B. Livid | A. Yellow 4 | B. Purple 3 |
17 Virginis A. | A. Light rose-tint | B. Dusky red | A. Red 4 | B. Red 3 |
ι Boötis | A. Pale orange | B. Sea green | A. Orange 3 | B. Green 4 |
α Herculis | A. Orange | B. Emerald, or bluish green | A. Yellow 2 | B. Blue 3 |
Instance of β Cygni.
By the adoption of the new and firmer method of registry, many of the differences now on record may turn out to be more apparent than real, and will probably disappear before the organised process of using an accepted chromatic scale with educated eyes. We have alluded to the otherwise complicated embarrassments and uncertainties incident to this kind of observation; yet still there is basis enough to inspire the warmest hope for exertion. The beautiful pair of stars forming β CYGNI may be cited as a strong instance in point of [*56] the agreement of many eyes and instruments, even by the prevalent rule-of-thumb system; because that object has an advantageous position in altitude when on or near the meridian, to facilitate this branch of inquiry. It will be borne in mind that β is an optical pair; for, as I have elsewhere remarked, strong colours in the pulcherrima of the heavens are not at all indicative of motion. To moderate the ordinary complaints about bias, magnifying power, aperture, achromatism, spherical correction, and local atmosphere - and to test the merit of gazing “with all its imperfections on its head” -the eyes and telescopes of various observers, at various places, have been summoned in aid; and the results of the requisition are to the following effect:-
OBSERVER | DATE | RECORDED | COLOURS | PLACE |
Sir William Herschel | 1779 | A. Red [11] | B. Blue | Slough |
Sir William Herschel | 1781 | A. Pale red | B. Beautiful blue | Slough |
Sir William Herschel | 1783 | A. Red or orange | B. Blue | Slough |
Sir John Herschel | 1816 | A. White, or yellowish white | B. Blue | Slough |
Sir John Herschel | 1830 | A. Yellow | B. Blue (superb) | Slough |
Herschel and South | 1822 | A. Yellow | B. Blue (strongly contrasted) | Slough |
Admiral Smyth | 1830 | A. Bright yellow | B. Fine blue | Bedford |
Admiral Smyth | 1837 | A. Topaz yellow | B. Sapphire blue | Bedford |
Admiral Smyth | 1849 | A. Golden yellow | B. Smalt blue | Bedford |
Admiral Smyth | 1857 | A. Orpiment yellow | B. Turquoise tint | Bedford |
Mrs. Smyth | 1830 | A. Fine yellow | B. Blue | Bedford |
Mrs. Smyth | 1857 | A. Orange yellow | B. Greenish blue | Bedford |
Struve the Elder [*57] | 1832 | A. Yellow (colours sun insines) | B. Ceralean blue | Dorpat |
Benedict Sestini | 1844 | A. Orange gold | B. Azure | Rome |
Piazzi Smyth | 1856 | A. Pale yellow | B. Blue | Teneriffe |
Piazzi Smyth | 1862 | A. Yellow | B. Bluish Green | Elchica |
Padre Secchi | 1857 | A. Reddish yellow | B. Green (fine colours) | Rome |
Rev. W.R. Dawes | 1857 | A. Orange yellow | B. Greenish blue | Haddenham |
Rev. W.R. Dawes | 1857 | A. Crocus yellow | B. Greenish blue | Haddenham |
Isaac Flectcher | 1850 | A. Yellow | B. Blue | Tarn-bank |
Isaac Flectcher | 1857 | A. Rich yellow | B. Brilliant blue | Tarn-bank |
Isaac Flectcher | 1864 | A. Rich yellow | B. Greenish blue | Tarn-bank |
Mrs. Flectcher | 1850 | A. Fine yellow | B. Bluish green | Tarn-bank |
Lord Wrotesley | 1857 | A. Golden yellow | B. Greenish blue | Wrottesley |
Lord Wrotesley | 1857 | A. Reddish orange | B. Clear blue | Wrottesley |
Captain Higgens | 1864 | A. Golden yellow | B. Bluish green | Bedford |
Rev. T.W. Webb | 1849 | A. Fine yellow | B. Ultramarine blue | Hereford |
Rev. T.W. Webb | 1849 | A. Fine yellow | B. Aqua colesti blue | Hereford |
George Knott | 1864 | A. Golden yellow | B. Bluish green | Cuckfield |
Mrs. Knott | 1832 | A. Variable, with ruddy cast | B. Emerald green | Cuckfield |
Dr. Lee [*58] | 1832 | A. Orange tinge | B. Bright blue | Bedford |
Dr. Lee | 1864 | A. Pinkish yellow | B. Cerulean blue | Hartwell |
Mrs. Lee | 1864 | A. Orange | B. Green | Hartwell |
Sir Rowland Hill | 1864 | A. Yellowish orange | B. Bluish green | Hartwell |
Lady Hill | 1864 | A. Yellow orange | B. Green | Hartwell |
W.R. Birt | 1864 | A. Yellow dashed with orange | B. Clear pure blue | Hartwell |
Samuel Horton | 1864 | A. Fiery yellow | B. Sky blue | Hartwell |
William Huggins | 1864 | A. Yellow | B. Blue | Tulse Hill |
J.R. Hind | 1864 | A. Pretty deep yellow | B. Sapphire blue | Twickenham |
C.G. Talmage | 1864 | A. Straw-coloured | B. Blue | Twickenham |
Frederick Bond | 1864 | A. Pale yellow | B. Light emerald green | Birmingham |
Rev. Robert Main | 1861 | A. Yellow | B. Blue | Oxford |
Rev. Robert Main | 1861 | A. Orange | B. Sea green | Oxford |
Mrs. Main | 1864 | A. Orange | B. Sea green | Oxford |
Rev. G. Fisher | 1864 | A. Bright orange | B. Violet | Hartwell |
Replies to my request.
In this enumeration all those observations given after the year 1856 were specially noted at my request - a request always acquiesced in with kind readiness by the parties addressed; and, as some of the replies contain matter in illustration of the recorded facts, the reader shall be treated to a few extracts from them in the order in which they were received.
Sir John Herschel.
Sir John Herschel, in answer to my inquiries, states - under date July 4th, 1864 -“From general recollection of the object when looked at, I should certainly say the observation of [*59] November 3rd, 1816, does not make the large star enough coloured.” And, to a query regarding one of Sir William’s epochs, his son has since informed me, that he copied verbatim what he found written as to β Cygni in the registered sheets taken from his father's diaries. The excerpt, which is valuable in this relation, stands thus :-
Sep. 12, ’79. Two fine stars. One red, the other blue.
Sep. 6, ’81. The large star (pr.) pale red, nlsi pretty red. The small, a beautiful blue. 227; under 460, estimation of colours the same.
Feb. 8, ’83. Large, red or orange. Small, blue or purple.
The Rev. W. R. Dawes.
The Rev. W. R. Dawes, in a letter of July 5th, 1864, says - “I succeeded last night in getting some very satisfactory observations of β Cygni for the colours of the components. I examined them with powers from 93 to 890. With 93,153,and 258, I pronounce the colours to be
“With one of Horne and Thornthwaite’s so-called ‘Aplanatics’ - which is certainly as achromatic as possible in all parts of the field - power 302, the colours were precisely the same as with the lower powers above quoted. Each star being alternately concealed by a small field in my solar eye-piece, the colours remained the same, so they were also with a perforated diaphragm over the whole object glass. For comparison I noted the colours of the components of α Herculis -
“The night was favourable for such observations,
being free from haze, and calm. The scarcely varied colours
with the highest powers compared with the lower, arises I
doubt not from the fine correction of this object-glass,
which is not over-corrected. In the violently
over-corrected Munich ones there is great difference
between the high and low powers. Mine [*60] is, I think, almost exactly like
your old Bedford favourite in respect of
correction.”
The same post also brought me dispatches of the same date
and on the same subject from my friends Captain Higgens and
the Rev. T. W. Webb. The Captain informs mc, that,
“after the spell of cloudy weather which we have had
so long, I almost despaired of being able to see the stars
last night; but a clear came on before sunset, and as the
darkness increased the definition became very good. I think
I never saw Jupiter so well before at so low an altitude as
I did soon after sunset. As the night advanced objects
became at rimes a little blotty, but on the whole we had a
good time of it.
“We had a long scrutiny of β Cygni. My wife
sees the pair as follows: A golden yellow; faded
sapphire blue; while I make A golden yellow, and B bluish
grey. I have no doubt we mean the same tints.
“I am sorry that I have not looked at this object
oftener, I see a note in my log of May 24th: A golden
yellow, B faintish blue, and I cannot help thinking that
the colour of the latter is not so vivid as I saw it last
year. I shall keep it well in sight during the remainder of
its appearance. We looked. at it with 115 to 200 (Cooke's
4-inch, 5-foot focus), which arc the powers best adapted
for my telescope for ordinary objects when testing
colours.”
The same night, July 4th, Captain Higgens turned his
instrument upon 95 Herculis charged with magnifying powers
of 115 and 200; the definition was good, and the normal
colours plain, but faintish.
The Rev. T. W. Webb.
The Rev. T. W. Webb entered warmly into the question,
saying; “We have had such a prevalence of cloud of
late, that, although I determined to take the very first
opportunity of attacking your object, I feared it might be
long deferred. Last night, however, proved unexpectedly
clear, and I set to work at once, and with various powers -
65 and 111 Ramsden, 170 Huyghens, 264 single lens, 323
Steinheil, and 600 Huyghens, and “macro-micro”-
I had the same result, which was [*61] quite independent of your own
estimates, as I had forgotten their precise terms. A
appeared to me a full yellow, varying to topaz, B an
‘aqua colestis’ blue, with a very slight tinge
of green.
“By ‘aqua colestis’- an old alchymical
name which I picked up I know not where - I mean the
splendid blue produced by adding ammonia to a solution of
sulphate of copper, - ammoniuret of copper is, I fancy, its
chemical name. The star reminded me at once of this, only
in comparison its blue appeared a trifle greener. This
comparison is made from memory only, as I have not seen any
of the liquid so called for years, and have not the
materials for making it at hand.”
Chemical tests are of material use in watching the colours
of stars, since they can be made and adapted at all times,
and, generally speaking, in all places.
G.Knott.
Mr. George Knott, who complied with my request (July 6th) as “a most pleasant duty,” reported in these terms: “On Monday evening at about 11 o’'clock the clouds cleared off, and, accompanied by my sole assistant, Mrs. Knott (‘ an astronomer's best assistant’ as I think the talented Astronomer-Royal for Scotland says somewhere), I adjourned to the observatory with a view of attacking the redoubtable β Cygni with my Alvan Clark refractor. The images of the stars were, however, rather confused, and the state of the atmosphere not favourable to colour observations, for which a really fine night seems almost as indispensable as for delicate measurements; but the following are our entirely independent estimates - valeant quantum:-
7½-inch Equatorial, full. aperture. Powers 173 and 328 - Thornthwaite’s aplanatic:-
With the aperture contracted to 3.7 inches, and negative
eye-piece of power-258, I thought A full golden, with ruddy
cast, and B pale blue green; and my estimates were
confirmed by Mrs. Knott.[*62]
“Last evening was finer, and I had
some very good views of this glorious pair with various
powers and apertures, and estimated
“With 3.2 inches aperture I thought the colour of B
more decidedly bluish, but still with a green cast. In the
finder (2 inches in aperture and magnifying power 20) B
appeared more decidedly bluish; but in the large telescope,
with apertures from 4 to 7.33 inches, its tint was a very
delicate and decided bluish green.
“To enable you to judge of my colour estimates
better, I fixes examined a and 95 Herculis, with the
following results:-
On the 10th of August, Mr. Knott wrote to me again,
announcing a fresh testimony-
“Thinking you might perhaps be interested to learn
what could be made of the colours of β Cygni with one
of the Silver on Glass reflectors, I wrote to an
ingenious correspondent (Mr. Bird of Birmingham) who has a
large one of his own make, 11 5/8 inches aperture, and of
excellent quality (he discovered the duplicity of the small
star following Procyon at a distance near the parallel,
consisting of two 9-10 mag. stars, distant from each other
about 0.6"), and asked him to oblige me by examining that
glorious pair.
“I received his reply a day or two ago, and now
proceed to quote the ipsissima verba of his report:-
“I had several looks at β Cygni for the colours of the stars, and my impression is, that the large star is a pale yellow and the small one a light emerald green stained with blue. The green is very obvious with a large aperture, and the field seems to be tinted with it. Mrs. Bird does not see the green so plainly, but a young lady staying with Its pronounced decidedly for the green, toned with blue. When the stars are put out of focus, the blue seems to be the most prominent. I should esteem it an honour to know that Admiral Smyth was in any way interested in the showing of colours by my silvered-glass speculum and Munich prism, &c. &c.” [*63]
“Thus the blue green colour of B is quite confirmed. The testimony of a reflector is very interesting on the point.”
Earl of Rosse.
Among those whom I petitioned on this occasion was the Earl
of Rosse, for I was desirous of obtaining such evidence
also as would be afforded by his noble gigantic
instruments. Unfortunately for my object, his Lordship was
in England, and a letter from Brighton of the 7th of July
thus informed me: “Although I have so often seen
β Cygni with both our telescopes, I have never made
any memorandum which would enable me to answer your
question. In fact I have merely regarded it as a splendid
object for visitors who were not astronomers.
“My assistant, I am sorry to say, is now absent at
the seaside, being very unwell, and I could not rely upon
any of the men about the observatory, as they have merely
been trained to work the instruments. The first opportunity
we will do our best to answer your question
accurately.”
I have merely inserted this in order to acquaint the
reader that, if Lord Rosse’s promised appreciation of
the colours of this double star comes to hand before the
finis of this brochure, it shall be duly
appended.
Isaac Fletcher.
Mr. Isaac Fletcher (July 9th) writes from Tarn Bank: Isaac Fletcher. “Since I received your request to examine the colours of the components of β Cygni the nights have all been cloudy except last night, when at 10 o’clock I levelled the 12-foot refractor at β, and examined the colours with various powers from 134 to 425. I make the colours as follows:-
“Afterwards on referring to the ‘Speculum,’ Mrs. Fletcher said that Mr. Dawes’s description of A as ‘crocus yellow’ was to her mind exactly specified.”
Dr. Lee
Dr. Lee, in a report from Hartwell dated 20th of July,[*64] remarks: “The colours of
β Cygni were observed with a power of 118 on the
equatorial instrument, after the stars had been examined
under an eye-piece magnifying 50 times. A diaphragm with a
wide slit was inserted, by which each star could be
examined separately; but no alteration was effected in the
estimation of the components as otherwise scrutinized. As
you seemed desirous of obtaining the appreciation of
various eyes, in addition to those sent to you already, I
may add that Miss Wilkinson, and Messrs. Drummond Davis,
Douglas Brown, and J. E. Hall, were agreed in pronouncing
the colours to be yellow and blue. Mr. D. A. Freeman,
however, thinks that the larger star appeared to him red,
not deep red; the smaller, under various powers, was light,
blue.
“With an eye-piece magnifying 240 times, Mr. Birt
was impressed with the great purity of the blue of
the star B, and on calling it to mind afterwards was
disposed to regard it as fine azure: Mr. Horton compared it
to the blue colour of the egg of the hedge-sparrow,
certainly a rural,- but very applicable, comparison.
“That the telescope was in excellent working order
was evinced by its sharp definition of the clusters in
Perseus, the annular nebula in Lyra, and various parts of
the moon’s surface,- she then being a little after
her first quarter. Your two variable stars following 80
Messier have re-appeared, and are duly noted for
use.”
Sir R. Hill.
Sir Rowland Hill, whom I have long appreciated as an amateur astronomer, [12] thus described the hues ill question: “On the 11th of July, we examined the fine double-star β Cygni, the recorded estimates of colour, with power 118, being as under-
“A lower power (50) gave a rather bluish tint to the smaller star; but the concealment of one of the stars by a [*65] diaphragm of metal did not alter the previous impressions; thus proving that the colours really emanated from the stars, and were not merely complementary tints.
Lord Wrottesley’s.
Besides Lord Wrottesley’s colour-notation of July 19th, above recorded, he was good enough to send me the micrometric leg. measures of the angle of position and the distance between the components of β Cygni, as expressly noted by Mr. Hough, his lordship's astronomical-assistant; and which I received on the 21st of that month. Now as these determinations directly confirm the declared opticity of this object, and therefore Lear out my dictum that vivid colours are by no means indicative of motion, I will enrol them here:
Mag./Colour. A. |
Mag./Colour. B. |
Position | W. | n. | Dist. | w. |
No. of Obs. |
Power |
Date 1864 |
3 Pale gold | 4-5 Bright blue | 56o 28' | 6.9 | 10 | 34".532 | 0.1w. | 10 | 459 | July 6 |
- Light orange | - Greenish blue | - | - | - | - | - | - | 83 | July 8 |
3 Light orange | 4-5 Light blue | 54o 28' | 6.8 | 10 | 34".405 | 6.8 | 10 | 450 | July 13 |
3 Golden orange | 4-5 Light blue | 55o 39' | 5.5 | 8 | 34".255 | 5.1 | 8 | 450 | July 14 |
In the above table W. and w. are the sums of the weights assigned to each single observation, divided by 10.
Fixity of β Cygni
The fixity of β Cygni being rather a standard point to establish in stellar Chromatics, we will repeat the results of the former operations, which are extended by reducing right ascensions and declinations into angles and distances, so that Bradley and Piazzi may be received in evidence. The whole presents a singular view of the agreement of various observers and various instruments in different places, and at different epochs, insomuch that ALBIREO must be deemed one of the best determined stars in the heavens, and therefore very fitting for the object before us. Its place in latitude and longitude is, of course, beyond cavil, it being settled by the meridian labours of many public observatories; while the extra-meridional operations exhibit the following deductions:- [*66]
OBSERVER. | POSITION. | DISTANCE. | EPOCH. |
Bradley | 57o 31' | 34.20" | 1755.00 |
Hersehel I.. | 54o 52' | 34.83" | 1782.45 |
Piazzi | 54o 31' | 34.28" | 1800.00 |
Struve I. | 54o 30' | 34.29" | 1821.76 |
Herschel II. and South | 54o 45' | 34.51" | 1830.54 |
Dawes | 55o 32' | 34.38" | 1822.98 |
Smyth, W.H. | 55o 23' | 34.2" | 1830.81 |
55o 36' | 34.4" | 1837.58 | |
56o 12' | 34.1" | 1854.67 | |
Fletcher | 56o 25' | 34.412" | 1850.83 |
55o 41' | 34.370" | 1857.42 | |
Lord Wrottesley | 55o 26' | 34.557" | 1857.47 |
Padre Seechi | 54o 57' | 34.419" | 1858.29 |
Smyth., C. Piazzi | 55o 25' | 34.59" | 1862.72 |
Hough | 55o 21' | 34.297" | 1864.53 |
Main | 56o 00' | 34.28" | 1864.63 |
Mean of the above.
And now I quote myself (Cycle, vol. ii. p. 450) in
remarking that these conclusions display a very remarkable
constancy both in angle find distance, especially as the
two components appear to be affected with proper motions,
the amount of which does not differ so much in the several
reductions, as in the course of direction of the march. [13] The following are the [*67] inferred present values and signs,
and the next rigorous comparison may decide between
PIAZZI. | BAILY. | ||||
Star A in AR. | -0s.07 | Dec. +0".05 | Star B in AR. | +0s.03 | Dec. +0".12 |
Star B | -0s.13 | -0".01 | Star B | +0s.05 | +0".04 |
Mr. Main's recent investigation gives no change in declination for A, and only 0s.002 in AR. : wherefore, considering all the infirmities still adhering to even the best observations, it seems necessary to wait a little longer for absolute conclusions.
W. Huggins.
Mr. William Huggins, of Upper Tulse Hill, wrote to me on
the 30th of July, announcing -” The earliest possible
opportunity to attack β Cygni occurred last night. In
a small box, which you will receive by the same post as
this note, you will find the colours of β, as they
appeared to me, with my telescope, last night. The coloured
solutions are to be observed in the dark, by means of the
light of a paraffin lamp.
“The blue pleases me much - with the yellow I am
less satisfied. I tried many other yellow-tinted solutions,
but with less success. The brighter star appears less
yellow when in tint is not heightened in the eye by the
simultaneous view of its blue companion. I estimated the
colours by viewing each star separately, and should name
the tints:-
“With my new spectrum apparatus I saw separated the
spectra of A and B. They differ, as was to be expected, in
as marked a degree as do thc colours of the stars to the
eye. I refrain from describing the spectra at present, as I
wish to re-observe them on an evening when the state of the
atmosphere is more favourable. The spectrum of B ie
exceedingly teazing to the eye. It being of the smallest
magnitude which admits of analysis by the spectrum with my
telescope of eight inches aperture.”
Now here is the proof of what has been advancing
respecting [*68] being near
enough in latitude.the difficulty of making these most
delicate observations, for I can aver that the night of the
20th was what a star-meter would call beautiful for
micrometric measures, yet the spectrum appliance required
the welkin not only to be fine, but superlatively fine. The
results, however, when obtained are wonderful: Sirius - a
brilliant object for the purpose - displays a spectrum
containing five strong bands, and numerous finer lines. The
occurrence of sodium, magnesium, hydrogen, and probably of
iron, has been negatively detected in that star’s
atmosphere, which is probably more charged with vapours
than that of our sun - a strong argument for the
pluralism of Worlds.
The changes of colour which stars of the first magnitude
are alleged to have undergone (see ante, page 16)
are hinged upon very inadequate bases; but we are preparing
to bequeath such matters to posterity in a more tangible
and convincing form than has hitherto been known. The
effects of light, absorption, and high refrangibilities are
now becoming unveiled.
J.R. Hind
Mr. John Russell Hind, on the 2nd of August, says, in
answer to my inquiry: “I looked at β Cygni this
morning, the first opportunity I have had since receiving
your note. I make the large star a pretty deep yellow,
while I cannot describe the colour of the small one to my
vision better than by your term, “sapphire blue.
Power 70.”
Mr. Hind then continues his letter with an interesting bit
of intelligence which, though not stringently necessary
here, may not prove altogether out of place.
“I shall write you about your remarkable companion
of Procyon [14], as soon as I receive
an answer from Dr. Luther as to the possible error of the
elements of Hebe at the time of your observation carried
back from the elements of 1847. Luther has Hebe in hand,
and I find by careful calculation that she would be within
a short distance of the spot where you saw the
orange-coloured star, but I believe it is difficult
to [*69] bring her near enough
in latitude when the longitudes agree. What a sensation you
would have created at that epoch (1833) had you recognised
this planet!”
This would have been a pleasing vision, but that - as I
have elsewhere declared - Mr. Fletcher’s observation
of 1850 precludes its indulgence. On consulting this
accurate astrometer on the subject, he pointedly says:
“It is true my observation is a lopsided one, the
distance most unfortunately not having been taken; but I
have no doubt whatever, and never had any, that the object
observed by you in '33 and by me in '50 is a star - a
variable one, no doubt.
“Not long after my observation was made my memory
was rigorously ransacked to recall the circumstances
attending it. The facts were these: after measuring the
position angle, I referred to the Cycle, and, finding my
angle nearly the same as yours in 1833, Brought,
“Well, this is only an optical double star. It is not
worth while noticing it any further.”
“Some one (I forget who) sometime ago suggested that
my measure of position referred to a very distant object in
the same direction; but I am certain that it did not, for
so great difference in distance from your star would at
once have rivetted my attention.”
On the 4th of August Mr. Hind addressed me again, saying:
“Since writing to you, Mr. Talmage, assistant in Mr.
Bishop’s Observatory, who is gifted with a remarkably
strong sight (though I cannot say how far that may be of
service in this case), has examined β Cygni with
powers 70, 108, and 200. He calls A straw-coloured and B
blue, but not so deep as sapphire blue.”
The Rev. R. Main.
The Rev. Robert Main on the 15th of August brought the great Oxford heliometer to bear on the object specially for this record, he having noticed the colours three years before. “My judgment,” he remarks, “is formed by the impression on the eye after forming a single image of each component by making the images cover each other as they now do at the zero, where they arc perfectly round. The magnitudes are 3 [*70] and 7 - a good 7. As I thought you would like to have cotemperaneous measures of this most ineresting star, I proceeded immediately to measure the distance and position, which are as follows: distance by a mean of 10 measures = 34".28. angle of position = 56o 00'.“
The Rev. G. Fisher.
In a “report“ to me of his eye-impression of the
hues of the components of β, Mr. Fisher, the
well-known arctic astronomer, observes, that to make his
estimation of colour be in accordancee with Admiral Smyth's
chromatic scale - which he had recorded his observations in
Dr. Lee's book - instead of a bright orange he would have
stated the colour of A bright yellow with a tinge of
red. “This,” he continues, “ affords
another instance of the necessity of establishing some
well-defined standard scale of colours for such cases, that
might be generally accepted by astronomers.”
“The magnifying powers used were 50, 118, and 240,
all of which in harmony as to the actual tints: these were
negative eye-pieces, but, from acident, we did not use the
single lenses you recommended us to do. From a very slight
display of prsimatic effect on the evening of September the
5th - which although fine was damp - we were led to suspect
a slight deposition of moisture on the object-glass; yet
the dew cap was on.
“By the enclosed extract which Dr. Lee has sent, you
will find that a few nights since his friend Mr. Norman
Lockyer pronounced A to be yellow, and B sea-green.”
The finding.
On overhauling the forgoing details, and sifting them through a numerical adjustment, it appears that the conclusive finding to be pronounced upon the colours of the star under trial, in general terms, is - according to the tabulated matter -
Now as the deliberative sentence the adjudged represents the medium hue of many observations, extending over a period of 85 years, and the object is in apparition to us copiously as to be in working sight from months, it constitutes a desirable target [*71] for the Tyro to trim his eye and instrument by, whenever he is bent upon a chromatic onset in that quarter. And as such it carries my recommendation.
[10] Notwithstanding this sombre view, there are rays of hope on the horizon. Already has the Astronomer Royal directed his powerful abilities to the subject-matter; and he has suggested an apparatus for facilitating observations of the of he spectra of stars. This is described in the twenty-third volume of the Astronomical Society's Notices, pages 188-191.
[11] For the prevalence of red in Sir William Herschel's star-tints, see the remarks, ante p.15.
[12] Sir Rowland's scientific bias was developed long before his great and effective POSTAL REFORM; he having been elected into the Astronomical Society in 1822.
[13] "Twenty years after the above was is written, my son, discussing β Cygni, says - “In magnitude, B is supposedly the slightly variable. In colour, there would seem to be yellow pulsations; at their maximum, converting the simple yellow of A into golden yellow, and the blue of B into greenish blue.”
“In position and distance these stars present one of the most remarkable instances known of near conformity amongst all ages, countries, and kinds of observers. In position this is partly due to tile large distance, but not altogether; and in distance, the same largeness should tell rather adversely; so that there is in fact only this only explanatory supposition left, if it does explain anything, viz. that, as Professor de Morgan has shown, in his treatise on the Theory of Probabilities, that there must be occasionally amongst men "lucky individuals;" so amongst the double stars, there may be found here and there a happy pair, where no one can well avoid making a good observation.”
[14] See the Cycle of Celestial Object, page 182; and the Speculum Hartwellian, pages 236-238.