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Admiral Smyth’s — Sidereal Chromatics

PART II. [*22]

DOUBLE STAR COLOURS CONTINUED

Opening remarks.

IN consecution of this fascinating subject, we will now follow the period of 1844, the date of the “Cycle,” by flint of 1860, the year in which the Hartwell Continuation appeared; after a further advertence to most of its matter, and considerable correspondence on the several points connected therewith. It has been suggested to me that some colours may undergo pulsations, but the adduced instances are mostly at low altitudes, where atmospheric influences are prevalent; and there may be a want of rigourous correction of the residual spectra of the refracting telescope. But embarrassments in the outset of any enterprize only enhance the value of proven examples.

It may be noted — en passant — that a slight perturbation pervaded the minds of observing neophytes on the averment pronouncing that there are only three primary colours, namely — red, yellow, and blue; and that the other four — orange, green, indigo, and violet — are de facto, to produced by combinations of the former, and are therefore secondary or compound colours. This is, however, comparatively easy, as well to suggest as to adopt; but when an arrogant Goethe — unversed even in first principles — steps forward in the pride and panoply of popularity to explain the physiological and chemical qualities of the same, in order to demolish the “nauseous precepts of Newton,” we are really taken aback by his temerarious effrontery. Only think, that because the artists in mosaic at Rome are said to employ 15,000 varieties of hues — each of which has 50 shades from the darkest to the lightest — he would saddle us with 750,000 different tints; and be it [*23] observed, the workmen in mosaic use opaque colours only. The intellectual giant had no business to go beyond his proper literary bounds, and poach upon science.

In now resuming our theme, we will submit a reprint, with increment, of the VIIth Chapter of the —

SPECULUM HARTWELLIANUM.

First the flaming red
Sprung vivid forth; the tawny orange next;
And next delicious yellow; by whose side
Fell the kind beams of all-refreshing green.
Then the pure blue that swells autumnal skies,
Ethereal play’d; and then of sadder hue,
Emerg’d the deepen’d indigo, as when
The heavy-skirted evening droops with frost.
Whilst the last gleamings of refracted light
Dy’d in the fainting violet away.

THOMSON.

The Sestini Comparisons.

In the Cycle of Celestial Objects (vol. i. page 300-4) I have dwelt generally upon the colours of double stars; and in the Bedford Catalogue, which forms the second volume of this work, have assigned such colours to all the objects as struck me at the time of observation. It seems that towards the close of the labours of Signor Benedict Sestini, of Rome, on a very extensive catalogue of stars, my book reached his hands, and led him to form the table which he has appended to his volume, [4] in hopes that the colours of stars may be more strictly watched. The conclusions which he had arrived at were, that of two thousand five hundred and forty stars (those of Baily’s Catalogue observed at Rome) the yellow stars are about half the total number, and equally distributed; the white stars are one-fifth, in scattered portions; and the orange rather more than one-fifth. The red and the blue are rare from the Pole to 30° of north declination; the blue then become numerous (=1/7) to the Equator, especially from [*24] AR 18h to 20h; and the red abound from 0° to 30°; south declination, and AR 16h to 20h.

Sestini’s method.

On Signor Sestini’s instituting the comparisons which he has described in his work, he carefully recorded the dates, as a step to ascertaining whether the colours may or may not be found to vary with time. Political furor — a deadly foe to science — drove De Vico, Sestini, and other distinguished members of the Collegio Romano, from their country; and the two former sought and found an asylum in America. In passing through London, Professor De Vico had given me notice of the use to which my Cycle had been applied; and I afterwards received a copy of Sestini’s work, with the following letter from the worthy author in English, dated George-town College, March 19th, 1849:

Soon after I had completed this collection of observations, I conceived the design of sending a copy to you, not only as a mark of respectful esteem, but also from having profiled by your Celestial Cycle in the arrangement and comparison of the observations that I myself had made in the Observatory of the Roman College. But the unmerited expulsion and exile that I and my brethren have suffered, have obliged me to leave almost everything, and the printed copies of the little Memoria remained in the printer’s hands, where I think they are yet. Luckily, a while ago I found a few copies in a trunk, sent to me after the death of our dear De Vico. Therefore I send you now what I could not send you before, and at the same time, and without troubling you, I would desire to know what you advise upon this sort of observations. And, as I have the same objective glass of Cauchoix that I have used in Rome to collect these observations, I desire to know if you approve a review, not entirely but sufficiently general in order to examine if the difference of the climate have any influence on the colour of stars. You can also, if you please, suggest more advisable means than those I have adopted, and I should be very happy if the opportunity of having the same and so good an objective glass that I have used for ten years in Italy could give me the means of lending some advantage to the science: what so sincere a lover of this beautiful science as you are can easily find. On another occasion, and when I become better acquainted with the English language, I hope to thank you for all your favours and kindness. Then also will I tell something of the new observatory of this George-town College, erected and very well furnished by the care of H. Curley, a very able and industrious professor, my colleague.
The observations made and published with my first Memoria are reprinted and collected together with all the others of this second Memoria. [*25] Nevertheless, if I had here a copy, I would join to the second. and I would send both to you.

Remarks to Sestini.

In reply to Signor Sestini, I expressed my satisfaction with the course of his inquiries, as they might yet be of great value in a very interesting branch of physical phenomena. He should, however, remember that the colours recorded in the Cycle were frequently noted after the eye was fatigued and biassed by previous working in an illuminated field, and reading minute divisions on graduated micrometer-circles. There were also the imperfections of the sight, the materials of the object-glass, and the various atmospheric media to be considered before any crucial exactness could be expected; but that still, under every objection, approaches to satisfactory conclusions must inevitably follow stricter attention to the subject. I therefore recommended occasional references to the heavens for this object only, with the eye kept in sharp order for the purpose, having carefully tested the capacity of that organ in strictly identifying the several gradations of colour. Many of the tints of stellar companions would of course turn out to be merely complementary contrasts; but the inherent colours would become additionally valuable, as strict observation upon them, under efficient means, advanced. Indeed, I added, it may be considered as fully proved, that the hue of some stars is not the effect of contrast, but a physical reality. [5]

Death of De Vico.

The unfortunate exiles — De Vico and Sestini — obtained a refuge in George-town, on the banks of the Potomac, in the United States; hoping for employment in the newly-erected observatory there. Shortly afterwards, in furtherance of instruments and other scientific objects, the former recrossed the Atlantic Ocean; but, worn with fatigue and anxiety of mind, he died in London on the 15th of November, [*26]
Though usually known as a successful comet-hunter, De Vice was alive to all other branches of celestial research; and he had promised me that, whenever opportunity offered, he would follow up “i colori insigni delle stelle.”

Ladies’ aid called in.

The question is pregnant with interest; and, considering that it may be advantageously encountered by any diligent, sharp-sighted amateur who, possessed of a good telescope and inclined only to easy and pleasing work, is nevertheless zealous to become useful in the cause of knowledge, I have herewith subjoined the list of chromatic comparisons or Sestini’s observations with mine; to which are added those colours which I have since noted at Hartwell. Several of them were confirmed in direct comparison by Dr. Lee; it was an occasion on which the eyes or ladies also were prized, and the tints were mostly pronounced without reference to the older records.
Here follow the details :-

Stars

STAR	Cycle No.	Epoch.	SMYTH A	B	SESTINI Epoch	A	B	SMYTH Epoch	A	B
35 Piscium	7	1837.9	Pale white	Violet	1844.8	Yellowish	Azure	1850.7	White	Purplish
13 P O Ceti	17	1832.8	Cream yellow	Small Blue	1845.8	Yellowish	Azure	1849.7	Yellowish	Fine Blue
146 P O Ceti	23	1837.9	Pale topaz	Violet	1845.8	Orange Yellow	Dull azure	1849.7	Yellow	Flushed blue
η Casseopeiae	29	1843.2	Pale white	Purple	1845.6	Yellow	Orange	1850.6	Dull white	Lilac
65 Piscium	31	1838.2	Pure yellow	Pale yellow	1844.8	Yellowish	Azure	1850.8	Pale yellow	Pale yellow
Psi Piscium	37	1833.9	Silvery White	Silvery White	1845.8	Fine Azure	Fine Azure	1849.7	Flushed white	Pale White
α Ursa Minoris	44	1838.2	Topaz yellow	Pale white	1843.6	Yellowish	Azure	1849.6	Yellow	Dull white
ζ Piscium	47	1839.0	Silver-White	Pale grey	1844.8	Yellowish	Dingy yellow	1849.7	White	Greyish
37 Ceti	48	1838.9	White	Light Blue	1844.8	Yellow	White	1849.7	Cream white	Dusky
ψ Casseopeiae	52	1836.3	Orange tint	Blue	1844.8	White	White	1850.2	Golden yellow	Ash coloured
83 P.I Piscium	54	1837.0	Yellow	Pale blue	1844.8	Yellow	Pale Azure	1855.4	Pale yellow	Bluish
γ Arietis	72	1837.9	Bright white	Pale grey	1844.9	White	White	1850.7	Full white	Faint Blue
λ Arietis[*27]	79	1830.9	Yellowish-white	Blue	1844.9	White	Pale azure	1857.7	Faint blue	Flushed blue
α Piscium	81	1835.9	Pale green	Blue	1844.8	White	White	1850.8	Greenish	Pale blue
γ Andromedæ	82	1843.3	Orange	Emerald Green	1846.5	Red orange	Lighter red	1850.3	Deep Yellow	Sea Green
14 Arietis	86	1833.9	White	Blue	1844.9	Yellowish	Bluish white	1857.7	Pale white	Grey
72 P.II Casseopeiae	97	1834.8	Pale yellow	Lilac	1845.6	White	White	1857.7	Yellowish white	Purplish
θ Persei	109	1833.6	Yellow	Violet	1845.6	Red orange	Lighter red	1849.6	Yellow	Dusky blue
π Persei	115	1838.8	Orange	Smalt blue	1845.7	Golden orange	Azure	1850.7	Reddish yellow	Blue
32 Eridani	147	1843.2	Topaz yellow	Sea-green	1845.9	Yellow	White	1850.3	Bright yellow	Flushed Blue
φ Tauri	158	1832.8	Light Red	Cerulean Blue	1845.8	Golden orange	Azure	1852.5	Pale red	Blue
χ Tauri	160	1831.9	White	Pale sky blue	1815.8	White	Azure	1850.7	White	Grey
62 Tauri	161	1835.9	Silver white	Purple	1845.8	White	White	1850.7	White	Pale purple
88 Tauri	169	1832.9	Bluish white	Cerulean Blue	1845.8	White	White	1852.5	Bluish white	Blue
τ Tauri	171	1831.9	Bluish white	Lilac	1845.8	Very white	Azure	1852.5	Pale white	Violet
ω Aurigae	174	1833.8	Pale Red	Light Blue	18457	White	White	1850.7	Flushed white	Light blue
62 Eridani	175	1831.9	White	Lilac	1845.9	Light yellow	Azure	1852.5	Pale white	Flushed blue
14 Aurigae	188	1832.8	Pale Yellow	Orange	1845.7	White	Azure	1850.7	Greenish yellow	Bluish yellow
23 Orionis	197	1835.2	White	Pale grey	1845.9	Yellowish	Bluish white	1850.2	Creamy white	Light blue
111 Tauri	198	1832.9	White	Lilac	1845.9	Yellowish	White	1857.7	Pale white	Lilac
118 Tauri	205	1838.9	White	Pale blue	1845.9	White	White	1850.2	White	Bluish
δ Orionis	211	1935.1	Brillant white	Pale violet	1843.9	Yellowish	Very white	1850.2	Pale white	Flushed white
λ Orionis	215	1813.1	Pale white	Violet	1843.9	Yellowish	Bluish white	1850.2	Pale yellow	Purplish
ι Orionis	218	1832.1	White	Pale blue	1843.9	White	Pale blue	1852.5	Pale white	Bluish
26 Aurigae	220	1833.1	Pale white	Violet	1845.7	Yellowish	Blue	1849.7	Deep blue	Pale blue
σ Orionis	222	1832.2	Bright white	Bluish	1843.9	Yellow	Azure	1850.3	White	Grey
ζ Orionis	223	1839.2	Topaz yellow	Light purple	1843.9	Yellowish	Azure	1850.3	Yellow	Flushed blue
γ Leporis	225	1832.1	Light yellow	Pale green	1843.9	Orange yellow	Orange red	1852.2	Pale yellow	Flushed
8 Moncerotis [*28]	245	18342	Golden yellow	Lilac	1845.9	Pale yellow	Yellowish	1850.8	Yellow	Flushed blue
15 Geminorum	247	1832.0	Flushed white	Bluish	1845.9	Orange	Yellowish	1852.4	Pale white	Ash coloured
20 Geminorum	252	1834.0	Topaz yellow	Cerulean blue	1815.9	Yellowish orange	Yellow	1849.7	Yellow	Pale blue
π² Canis Majoris	270	1834.1	Flushed white	Ruddy	1845.9	Yellowish	Reddish	1851.3	Bluish white	Ruddy
α Geminorum	292	1843.1	Bright white	Pale white	1845.9	Yellowish	Yellow	1849-2	Very white	Pale white
ζ Cancri	315	1813.1	Yellow	Orange tinge	18460	Yellow	White	1849.2	Yellow	Bright Yellow
φ² Cancri	320	1813.2	Silvery white	Silvery White	1846.0	Yellowish	White	1819.2	White	Pale white
υ¹ Cancri	321	1848.2	Pale white	Greyish	1846.0	White	White	1819.2	White	Dusky white
72 P.VIII Argo Navis	323	1830.8	Red	Green	1846.1	Orange red	Yellowish	1851.3	Orange	Bluish green
108 P.VIII Hydrae	326	1839.1	Pale yellow	Rose tint	1846.0	Orange	Orange	1849.2	Full yellow	Flushed
ι Cancri	336	1836.2	Pale orange	Clear blue	1846.0	Fine orange	Azure	1851.3	Dusky orange	Sapphire blue
τ¹ Hydrae	360	1831.9	Flushed white	Lilac	1846.1	Yellow	Yellow	1851.3	Pale white	Dusky
6 Leonis	363	1832.2	Pale rose tint	Purple	1846.0	Fine orange	White	1851.3	Flushed yellow	Pale purple
7 Leonis	364	1832.2	Flushed white	Violet tint	1846.0	Rother blue	White	1851.3	Bluish white	Pale violet
9 Sextantis	371	1832.2	Blue	Blue	1846.0	Dingy orange	Dingy orange	1851.3	Flushed blue	Pale blue
33 Sextantis	384	1839.1	Topaz yellow	Smalt blue	1816.1	Pale yellow	Pale yellow	1851.2	Rich yellow	Ceruleau blue
54 Leonis	391	1839.3	White	Grey	1846.0	Yellow	White	1851.3	Silvery white	Ash coloured
Phi Leonis	405	1831.2	Pale yellow	Violet	1846.2	Pale yellow	White	1851.3	Pale yellow	Dusky red
90 Leonis	421	1835.4	Silvery white	Purplish	1846.1	White	White	1851.3	Silver white	Pale purple
δ Corvi	446	1831.3	Pale yellow	Purple	1846.3	Slightly yellow	White	1851.3	Light yellow	Purple
24 Coma Berencis	451	1836.1	Orange colour	Emerald tint	1844.4	Gold	Azure	1851.3	Orange	Lilac
143 P.XII. Virginis	453	1833.3	Pale yellow	Greenish	1846.3	Red	Azure	1851.3	Yellowish	Flushed blue
12 Canum Venaticorum	466	1837.4	Flushed white	Pale blue	1844.5	Yellowish	Blue	1850.5	Full white	Very pale
ζ Ursa Majoris	480	1839.3	Brilliant white	Pale emerald	1841.5	White	Yellowish	1819.2	White	Pale green
ι Boötis [*29]	508	1838.2	Pale yellow	Creamy	1844.5	Orange yellow	Azure	1850.6	Light yellow	Dusky white
π Bootis	517	1836.5	White	White	1844.4	Yellow	Less yellow	1850.6	White	Creamy
10 Hydrae	519	1831.5	Pale orange	Violet tint	1846.4	Yellow	Yellowish	1851.4	Deep yellow	Reddish violet
212 P.XIV. Librae	524	1833.4	Straw colour	Yellow	1846.3	Orange	Orange	1851.4	Yellow	Dusky
44 Boötis	529	1842.5	Pale white	Lucid grey	1844.5	Orange	Orange	1858 6	Pale yellow	Dusky
δ Boötis	537	1835.5	Pale yellow	Light blue	1844.5	Gold yellow	Yellowish azure	1851.3	Yellow	Lilac
μ¹ Boötis	542	1832.3	Flushed white	Greenish white	1844.5	Yellow	Yellowish azure	1860.6	Yellowish	Greenish white
ζ Corona Borealis	549	1842.6	Bluish white	Smalt blue	1844.5	White	White	1850.6	Flushed white	Bluish green
54 Librae	558	1842.5	Bright white	Pale yellow	1844.4	Orange	Orange	1850.6	Creamy white	Pale yellow
β Scorpii	559	1833.4	Pale white	Lilac tinge	1846.4	Yellow	Whitish	1851.4	Yellowish white	Pale blue
κ¹ Herculis	560	1835.4	Light yellow	Pale garnet	1844.5	Yellow	Orange	1851.3	Pale yellow	Reddish yellow
ν Scorpii	561	1831.5	Bright white	Pale lilac	1846.5	Yellowish	White	1850.6	Pale yellow	Dusky
σ Scorpii	568	1838.3	Creamy white	Lilac tint	1846.5	Yellow	White	1851.4	Dusky white	Plum colour
236 P.XVI Scorpii	593	1833.4	Yellowish white	Pale green	1845.5	Yellow	White	1851.4	Creamy white	Greenish
μ Draconis	602	1839.5	White	White	1844.5	Yellow	Azure	1850.7	White	Pale white
36 Ophiuchi	604	1842.4	Ruddy	Pale yellow	1846.5	Orange	Yellow	1851.4	Ruddy tint	Yellowish
39 Ophiuchi	607	1838.5	Pale orange	Blue	1846.5	Orange	Yellow	1851.4	Pale orange	Bluish
ν Serpentis	610	1832.6	Pale sea green	Lilac	1846.5	Yellow	Red	1851.4	Silvery tint	Native copper
ρ Herculis	613	1839.7	Bluish white	Pale emerald	1844.4	Yellow	Deeper yellow	1850.5	Greyish	Greenish
53 Ophiuchi	618	1836.5	Bluish	Bluish	1844.5	Bluish	Bluish	1850.5	Greyish	Pale blue
95 Herculis	631	1838.8	Greenish	Cherry red	1844.5	Gold yellow	Gold yellow	1851.3	Pale green	Reddish
70 Ophiuchi	633	1842.5	Pale topaz	Violet	1845.9	Fine orange	Copper colour	1849.5	Topaz yellow	Purplish
ω Draconis	672	1837.9	Orange yellow	Lilac	1844.5	Reddish	Red orange	1851.3	Orange	Lilac
15 Aquliae	678	1831.6	White	Lilac tint	1846.5	White	Yellow	1851.4	Yellowish white	Red lilac
28 Aquilae	699	1831.4	Pale white	Deep blue	1844.5	White	Yellowish	1851.4	Dusky white	Lilac blue
β Cygni	700	1837.6	Topaz yellow	Sapphire blue	1844.5	Orange gold	Azure	1849.6	Golden yellow	Smalt blue
ε Sagittae [*30]	704	1833.8	Pale white	Light blue	1844.5	Yellow	Bluish yellow	1850.6	Faint yellow	Bluish
54 Sagittarii	705	1837.6	Yellow	Violet	1845.5	Orange	White	1850.7	Yellow	Pale Lilac
ζ Sagittae	718	1838.6	Silvery white	Blue	1844.5	Yellowish white	Azure	1850.6	Flushed White	Cerulean blue
56 Aquilae	722	1834.6	Deep yellow	Pale blue	1846.5	Yelllow	Yellow	1850.6	Yellow	Bluish
κ Cephei	743	1838.8	Bright white	Smalt blue	1844.6	Yellowish	Azure	1851.3	Pale yellow	Blue
γ Delphni	769	1839.7	Yellow	Light emerald	1844.5	Orange	Yellow	1850.7	Golden yellow	Flushed grey
ε Equulei	770	1838.8	White	Lilac	1844.5	Gold orange	Azure	1551.4	Pale yellow	Bluish lilac
1 Pegasi	782	1833.9	Pale orange	Purplish	1844.5	Orange	Azure	1851.4	Deep yellow	Lilac blue
β Cephei	789	1843.1	White	Blue	1844.6	White	White	1851.3	Yellowish	Flushed blue
3 Pegasi	790	1837.8	White	Pale blue	1844.5	White	Yellow	1850.5	Flushed white	Greyish
ε Pegasi	794	1833.6	Yellow	Blue	1844.5	Gold yellow	Azure	1851.4	Bright yellow	Blue lilac
μ Cygni	795	1839.6	White	Blue	1841.5	Yellow	More yellow	1850.6	White	Pale blue
29 Aquarii	800	1830.8	Brilliant white	White	1846.5	Red orange	Same. lighter	1852.7	White	Bluish
χ Cephei	809	1839.6	Bluish	Bluish	1844.6	White	Yellowish	1851.4	Flushed	Pale blue
ζ Aquarii	813	1812.6	Very white	White	1845.8	Orange yellow	Pale yellow	1859.2	Flushed white	Creamy
δ Cephei	815	1837.7	Orange tint	Fine blue	1841.8	Orange	Azure	1819.2	Deep yellow	Ceruleau blue
τ¹ Aquarii	822	1838.7	White	Pale garnet	1845.5	White	Azure	1819.2	Pale white	Flushed
ψ Aquarii	833	1834.9	Orange tint	Sky blue	1845.8	Gold	Azure	1850.8	Topaz yellow	Ceruleau blue
94 Aquarii	834	1838.9	Pale rose tint	Light emerald	1845.8	Orange yellow	Orange	1850.5	Orange tint	Flushed blue
101 P.XXIII. Casseopeiae	839	1830.9	Light yellow	White	1845.6	White	Yellowish	1852.7	Pale white	Yellowish
107 Aquarii	844	1832.8	Bright white	Blue	1845.8	Yellowish white	Yellowish	1850.7	White	Purplish

Anomalies. [*31]

All the differences in the above list are subject to several doubts, and many of the records have been noted without a very strict attention to the question. In the Cycle, the main disagreements arc mentioned between the tints of stars as given by Sir William Herschel and myself; and the anomaly is partly accounted for by his peculiarity of vision, and partly by the composition of metal in his reflectors. But I am at a loss why refractors should differ so widely as here shown ; and therefore hope the subject will be more closely pursued than it has hitherto seen. We are aware that the notations independently made at various epochs will vary in term, though to the observers mind they may mean nearly the same tint, still some of the differences mentioned by Signor Sestini in his interesting Memoir arc singularly striking. He says — “Now, beginning with the companion of γ Andromedæ, we have Smyth emerald-green and Sestini white; but Herschel and Struve at another date call it azure. Moreover, observing it again after a lapse of two years, and four years after Smyth, I find it no longer white, but a strong blue !” And again — now see B (95) Herculis ; according to Smyth, one greenish and the other red ; but we think them both golden yellow. A Ophiuchi, by Smyth, one ruddy and the other pale yellow, but we both take them as being orange. The contrary occurs in ι Boötis, the components of which by Smyth are both pale yellow; but we deem one to be orange and the other azure.

Sir David Brewster’s Experiment.

Under the circumstances already alluded to, I am not at this stage disposed to theorise on the objects thus brought into juxta-position: and the colours of double-stars must be much more accurately assigned, and more ably experimented upon, before we can really admit that the nature and character of those suns do actually change in short periods. Sir David Brewster observes, that there can be no doubt that in the spectrum of every coloured star certain rays are wanting which exist in the solar spectrum; but have no reason to believe that the absent rays are absorbed by any atmosphere through [*32] which they pass. And in recording the only observation perhaps yet made to analyse the light of the coloured stars, he says :- “ In the orange-coloured star of the double-star ζ Herculis, I have observed that there are several defective bands. By applying a fine rock-salt prism, with the largest possible refracting angle. to this orange-star, as see in Sir James South's great achromatic refractor, its spectrum had the annexed appearance (in the Campden Hill Journal), clearly showing that there was one defective band in the red space, and two or more in the blue space. Hence the colour of the star was orange, because there was a greater defect of blue than of red rays.” This instance shows, that an approximation by instrumental means to the spectra of the brighter stars ought not to be despaired of ; and that prospect should not admit of any relaxation in our present motive call.

Teneriffe Experiment.

In the year 1856, on my son’s going to the island of Teneriffe to make his “Astronomical Experiment,” it occurred to me that it would be a singularly fine opportunity to test sidereal polychromy; since it would be marked by a spot where some thousands of feet of the grossest portion of the atmosphere are eliminated.
This meritorious expedition, which “at once converted into an actual and successful tact a theoretical idea, long thought well of, but never previously carried into practice,” may be recognized as the foundation of the of the branch so appropriately designated Mountain Astronomy. Indeed the advantages of elevated stations are sufficiently obvious to countenance the hope of reaping, thereby, results of the utmost importance to knowledge. Newton himself sounded a tocsin to this effect, in asserting that telescopes “cannot be so termed as to take away that conclusion 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.” It was under a conviction of this truth — and having a personal knowledge of both sites — that I earnestly wished my friend Lassell his huge equatorial on ætna, instead of Malta.[*33]
Such being the justifiable expectations of the problem, my son accordingly scrutinised the following stars from the “Cycle” for me; they having been chosen out of those objects which then happened to be in apparition from the mountain, during his interesting continuance upon it. The observations were made at two stations: the colours noted on the 29th of July and 4th of August were examined with the 5-foot Sheepshanks equatorial, at Guajara, a height of 8870 feet; and those of September 4th, 5th, and 6th, were made with the Pattinson telescope of 7.25 inches aperture, and parallactic movement, at the Alta Vista, where the altitude is 11,000 feet. The following are his registered results, with comparisons from the “Cycle ;” Which last are of various dates from 1830 to 1843:-

OBJECTS	TENERIFFE		BEDFORD
JULY 29th.
α Herculis	A. Cadmium yellow	B. Greenish	A. Orange	B. Emerald, or blue
39 Ophiuchi	A. Pale yellow	B. Faint blue	A. Pale orange	B. Blueish green
5 [V?] Serpentis	A. Pale yellow	B. Warm lilac	A. Pale yellow	B. Light grey
ξ ? Herculis	A. White	B. Bluish	A. Blueish white	B. Pale emerald
95 Herculis	A. White	B. White	A. Light apple green	B. Cherry red
70 Ophiuchi	A. Pale yellow	B. Greyish	A. Pale topaz	B. Violet
α Lyrae	A. White	B. Violet	A. Pale sapphire	B. Smalt blue
AUGUST 4th.
α Herculis	A. Cadmium yellow	B. Greenish	(as above)	(as above)
95 Herculis	A. and	B. both yellow with a tinge of bluish green	(as above)
70 Ophiuchi	A. Yellow	B. Warm green	(as above)
5 Aquilae	A. Pale yellow	B. Bluish C. Blue	A. White	B. Lilac. C. Blue
28 Aquilae	A. White	B. Blue	A. Pale White	B. Deep blue
β Cygni	A. Pale yellow	B. Blue	A. Topaz yellow	B. Sapphire blue
186 Antinoi	A. Yellow	B. Blue	A. Pale white	B. Sky blue
SEPTEMBER 4th
α Scorpii	A. Coppery Red	B. Blue	A. Fiery red	B. Pale
α Herculis	A. Orange	B. Greenish	(as above)
ζ Sagittae [*34]	A. Yellow	B. Blue	A. Silvery White	B. Blue
α¹ Capricorni	A. Yellow	B. Blue	A. Pale yellow	B. Blue
1 Pegasi	A. Yellow	B. Blue	A. Pale orange	B. Purplish
β Cephei	A. White	B. Purple	A. White	B. Blue
3 Pegasi	A. Whitish	B. Warm grey	A. Pale	B. Pate blue
ζ Piscium	A. Yellow	B. Grey	A. Silver white	B. Pale grey
γ Arietis	A. White	B. White	A.Brilliant sapphire	B. Pale grey
λ Arietis	A. Pale yellow	B. Bright lilac	A. Yellowish	B. Blue
α Piscium	A. Blue	B. White	A. Pale green	B. Blue
SEPTEMBER 5th.
α Aquilae	A. Pale yellow	B. Grey	A. Pale yellow	B. Violet tint
γ Delphni	A. Cadmium yellow	B. Orange tinge	A. Cadmium yellow	B. Bright emerald
τ¹ Aquarii	A. Light yellow	B. Pale violet	A. White	B. Pale garnet
α Piscis Australis	A. White	B. Blue	A. Reddish	B. Deep sky blue
ψ Aquarii	A. Cadmium yellow	B. Blue	A. Orange red	B. Sky blue
94 Aquarii	A. Yellow	B. Light warm blue	A. Pale rose-tint	B. Light emerald
101 Casseopeiae	A. Light yellow	B. Grey blue	A. Light yellow	B. Violet
	C. Blue	D. Violet	C. Blue	D. (not noticed)
107 Aquarii	A. Pale yellow	B. White	A. Bright yellow	B. Blue
35 Piscium	A. Yellow	B. Pale violet	A. Pale white	B Violet tint
113 Ceti	A. Rich yellow	B. Warm grey	A. Cream yellow	B. Smalt blue
γ Arietis	A. Light yellow	B Light yellow		(as above)
222 Arietis	A. Grey	B. Blue	A. Topaz yellow	B. Deep blue
	C. Lilac	D. Yellow	C. Lilac	D. Pale blue
α Piscium	A. White	B. White	(as above)
γ Andromedæ	A. Orange	B. and C. Green	A: Orange	B. Emerald green
32 Eridani	A. Orange	B. Greenish	A. Topaz yellow	B. Sea Green
SEPTEMBER 6th
σ Casseopeiae	A. Pale yellow	B. Light blue	A. Flushed white	B. Smalt blue
35 Piscium	A. Pale yellow	B. Pale lilac	(as above)
113 Ceti	A. Yellow	B. Warm grey	(as above)
146 Ceti	A. Yellow	B. Pale violet	A. Pale topaz	B. Violet tint
π Casseopeiae	A. Yellow	B. Indian red	A. Pale white	B. Purple
65 Piscium	A. White	B. White	A. Pale yellow	B. Pale yellow
ψ¹ Piscium	A. White	B. White	A. Silvery white	B. Silvery White
ζ Piscium	A. White.	B. Reddish	(as above)

General discussion of the foregoing list. [*35]

In the preceding list there to be a very general similarity of eye-judgment between my son and myself; whence it would appear that the difference made by 11,000 feet of the lower atmosphere on the colours, is not so great as might have been anticipated. But the most striking and inexplicable difference in the comparison is that of 95 Herculis; for, in the observations at the Peak of Teneriffe, the tints of the two stars — though not quite the same at each examination — were judged to be common to both, and the impression was ratified by the evidence of some Spanish visitors at the astronomical aerie. Not a little taken aback, however; by the unexpected announcement — the more unexpected in consequence of the general agreement which existed throughout the list, even in some of the most delicate hues I took the earliest opportunity of returning to the charge, when there was the A Apple green and B cherry red, as recorded by me nearly a quarter of a century before! To avoid all suspicion of bias I invited my colleagues to the task, and soon received an answer from Mr. Dawes, saying — “On referring to my colour-estimations, I find that they agree very nearly with your own.” Lord Wrottesley pronounced A to be greenish and B reddish in 1857.46; and at the same epoch Mr. Fletcher reported that A, to his eye, was light green and pink ; while to his brother H. A. Fletcher one was bluish green and the other orange, and to Mr. T. W. Carr A was either light blue or green, and B dull red. To add to the perplexity of the instance, Sestini saw them both golden yellow at Rome, in 1844; while his colleague, De Vico, in the memoirs of the “Osservatorio dcl Collegio Romano,” in the same place and with, the same instrument, dubs them “rossa e verde.” Assuredly this is most passing strange, since the means in these cases were pretty equally powerful, and chromatic personal equation-or the faculty in a greater or less degree of appreciating differences of colour, cannot be entitled to consideration with the discrepancies of 95 Herculis.

ENDNOTES

[4] A selection from these, twenty nine in number, was communicated by the late Professor de Vico to Schumacher at Altona, in Isis; who published the details in Astronomische Nachrichten; No. 684.

[5] Secchi (Osservatorio del Collegio Romano) says — “Until now a means has been wanting to decide the degree of colour of double stars with precision. If I do not deceive myself I have succeeded, at least to indicate a means by which we can determine it without mistake in centuries to come: this means is derived from the spectrum of the electric spark (questo dallo spectiro della scintilla electrica), and I will shew it in conclusion. My attempts hitherto, for want of time and apparatus, have not been reduced to practice.”

Last Update : 26th April 2017