ARTICLE PAGES

Admiral Smyth’s - Sidereal Chromatics

INTRODUCTION LETTER

[*v.] TO JOHN LEE, ESQ., Q.C., LL.D.,
F.R.S., F.S.A., F.R.A.S., F.G.S., ETC.

St. John’s Lodge, 1-8-64.

MY DEAR FRIEND,

ALTHOUGH the discoveries in sidereal astronomy since the advent of the elder Herschel, have been equally gratifying and marvellous, there is every prospect of still further triumphs for assiduity and observational skill to obtain. For this most desirable consummation, every department to which practical vigilance can render its aid, ought to be furnished to the utmost with sifted materials, in order that, from a mass of recorded facts, safe conclusions may be arrived at. This impression, together with the present number and efficiency of achromatic telescopes, induces me again to call attention to the still vague and indeterminate state in which the COLOURS of multiple stars are registered, with a word or two as to the steps for bettering it. In our confabulations on this material point we agreed, that a reprint of my former suggestions in a portable form, would probably attract the notice and suit the convenience of many observers; the present brochure was therefore undertaken to carry out this view.

The method which has hitherto been pursued in these examinations is both trite and inexact, having been mostly practised when fixed eye, at all times a delicate organ, has been fatigued by taking and reading-off measures [*vi.] made with an illuminated field; and some oil-servers register the position and distance with the magnitudes of the objects, without a word as to their colours. Now I would advise that for this purpose the objects be brought into a dark field, and only on very fine nights, by those amatures scientiæ; who are possessed of powerful telescopes, but yet have no intention to labour in that most delicate branch of celestial operations, the mensuration of the angle of position of double stars and their distance from each other. In the discrimination of colours zeal and ability can render good service to the general cause, yet without the observers’s encountering heavy work or foiling on monotonous reductions.

Having already stated the why and the wherefore of the question elsewhere, it only remains to show the necessity of acting in concern, and on a settled plan, so as to obtain a more exact nomenclature in χρωμα. Our having noted the colours from fruits, flowers,vegetables, jewels, and the like, involves conflicting uncertainty, since most of those objects are of various tints. Indeed, as a proof of the imperfection of such comparisons, I will here cite a sample from my own practice, placing the inexact epithets which I have used in Roman print, and what was probably meant is expressed in Italics:-

From various auspicious circumstances, the present appears to be a very seasonable time for bringing this interesting natural feature before our volunteer astronomers; and, as you so liberally undertook to furnish them with my hints on the subject, the recommendation before us is launched; while to it is appended a chromatic diagram, as a first step towards simplifying the records hereafter to be obtained.

This pamphlet merely touches upon the common order of colours and their complementaries — without entering into the relation of the light absorbed to the light reflected — and by no means pretends to treat of the almost infinite shades and tints which philosophers and artists distinguish in nature. The recent discovery or a mono-chromatic light occasioned by the [*viii.] combustion of the new and curious metal Thallium, establishes the Newtonian theory of the spectrum, as being more correct than the ostensible dogma of only three primary colours, which had nearly supplanted it of late; while the mysterious lines within the arch of seven primitively refracted rays, open out a wonderful scope in the development of planetary and sidereal physics. Indeed the rigorous spectrum analysis now in hand, as applied to the stars – albeit of operose difficulty — is rich in promise; and already do the observations of Kirchoff, Donati, and Rutherford., with the masterly experiments of Miller and Huggins, indicate that a cause for the difference of colour may thus be sought in the various constitutions of the investing stellar atmospheres.

But, even were those beautiful inquiries more matured and correlative than they are as yet, the call now made to the efficiently armed amateur would not be the less necessary, seeing what a series of well observed and accurately described facts may be reaped by diligent appliance.

You must well remember the attempt that we made in July 1829, hereafter recounted, to come to a conclusion regarding the colours of the double-star familiarly designated Cor Caroli; and how eleven pairs of eyes, of which six couple were directed by ladies, widely differed in their mental appreciation of the hues before them. Yet in the autumn of 1855, myself and two other observers were unanimous in pronouncing that the same object was −

A. Pale reddish white. & B. Lilac ; the which might have been more satisfactorily and [*ix.] more exactly expressed according to the diagram herein proposed, in this form:- A. Red ⁴, B. Purple ³.

At this last epoch, by direct experiment on the mild tints of Cor Caroli and the stronger ones of Rasalgett, I was satisfied that, however telescopes may vary as to the intensity of the hue imparted, according to the accuracy of their chromatic correction, and even under different powers by the same instrument, yet the general tone is in fair accordance. It follows then, that the adoption of the proposed line of action, till a better one is presented, will assuredly be productive of many desirable results; and therefore, hoping for a realization of the wish, I am always

Yours very truly,

W.H.Smyth

Last Update : 26th April 2017

Southern Astronomical Delights © (2012-17)

For any problems with this Website or Document please e-mail me.