The spectroscope and its applications / by J. Norman Lockyer.

Date:
1873
Catalogue details

Licence: Public Domain Mark

Credit: The spectroscope and its applications / by J. Norman Lockyer. Source: Wellcome Collection.

Provider: This material has been provided by the Royal College of Physicians of Edinburgh. The original may be consulted at the Royal College of Physicians of Edinburgh.

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    saw that the hydrogen lines were much developed ; and in a further examination, carried on by the method in which the spectrum of hydrogen and other vapours which he wished to examine were absolutely visible in the field of view at the same time as was the spectrum of the star, Mr. Huggms was astonished to find that the hydrogen lines no longer occupied their usual positions, but that they were all jerked, so to speak, a little to the side of the place which they occupied in the spectrum of the hydrogen which he rendered incandescent in his tubes. The F line of hydrogen which he observed in the spectrum of Sirius he found did not exactly occupy the same position in the spectrum as did the Jlydrogen at Atmospheric pressure SolarSpectrum Line F Spectruvt, of Sirius Hydrogen in Vacuum tube Fig. 56—Alteration of wave-length of the hydrogen in the atmosphere of Sirius. actual F line of hydrogen, the incandescent hydrogen with which he compared it (Fig. 57). Owing to a phy- sical law, which I have not time to explain to you now, it is perfectly easy, by means of the prism, to determine the velocity with which the light-source is moving to or from us; and therefore, if this holds