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Updated: June 19, 2025
Balmer gave some time since, in the case of the hydrogen spectrum, an empirical formula which enabled the rays discovered later by an eminent astronomer, M. Deslandres, to be represented; but since then, both in the cases of line and band spectra, the labours of Professor Rydberg, of M. Deslandres, of Professors Kayzer and Runge, and of M. Thiele, have enabled us to comprehend, in their smallest details, the laws of the distribution of lines and bands.
The attendant laborious investigation, by the aid of photography, of metallic spectra, seemed to indicate the existence of what he called "basic lines."
It included 4,051 stars, distributed over a zone of the heavens extending from 20° north to 20° south of the celestial equator. More than half of these were white stars, while red stars with banded spectra occurred in the proportion of about one-thirteenth of the whole.
The absorption lines of the terrestrial atmosphere would form the best standard for this purpose if those which are sufficiently fine can be photographed. Wave Lengths. The determination of the wave lengths of the lines in the stellar spectra will form an important part of the work which has not yet been begun.
Professor Lockyer went on to state, however, that he is by no means altogether dependent upon the observations made at South Kensington. For certain purposes the Royal Observatory at Greenwich is in requisition, and there are three observatories at different places in India at which photographs of the sun-spots and solar spectra are taken regularly.
In 1868 Huggins compared the spectrum of Winnecke's comet with that of a Geissler tube containing olefiant gas, and found exact agreement. Nearly all comets have shown the same spectrum. A very few comets have given bright band spectra differing from the normal type. Also a certain kind of continuous spectrum, as well as reflected solar light showing Frauenhofer lines, have been seen.
It will contain the approximate place of each star for 1900, its designation, the character of the spectrum as derived from each of the plates in which it was photographed, the references to these plates, and the photographic brightness of the star. Catalogue of Spectra of Faint Stars. This work resembles the preceding, but is much more extensive.
Unmindful of the starving hordes of Paris and Berlin, of plague-swept Russia, or of the drowned thousands of the North Baltic Fleet, these two men calmly studied the procession of the stars the onward bore of the universe through space, and the spectra of newborn or dying worlds. It was a suffocatingly hot night and their foreheads reeked with sweat.
The spectra then both disappeared; and then the internal spectrum was blue; and then, after a second disappearance, became yellow, and lastly pink, whilst the spectrum of the field varied into red and green.
This wheel, by means of an axis, was made to whirl like a top; and on its being put in motion, a green colour was produced, corresponding with great exactness to the reverse spectrum of red. In contemplating any one or these reverse spectra in the closed and covered eye, it disappears and re-appears several times successively, till at length it entirely vanishes, like the direct spectra in Sect.
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