Researches on Astronomical Spectrum-photography

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J. Wilson and son, 1884 - Astronomical photography - 11 pages
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Page 272 - ... eliminated. The April number of the American Journal of Science contains an account of a photograph of the spectrum of this nebula taken by Dr. Huggins. I have not found the line at X 3730, of which he speaks, though I have other lines which he does not appear to have photographed. This may be due to the fact that he had placed his slit on a different region of the nebula...
Page 267 - ... or 12-inch achromatic without loss by diaphragms ; 3d, to permit the slit to be easily seen, so that the star may be adjusted on it; 4th, to avoid flexure or other causes that might change the position of the spectrum on the sensitive plate in pointing the telescope first on one and then on another object; 5th, to admit of observing the spectrum on the sensitive plate at any time during an exposure without risk of shifting or disarrangement. The dispersion is produced by two heavy flint prisms...
Page 265 - March of the same year, when the spectrum of this star (Sirius) was caused to fall upon a sensitive collodion surface, an intense spectrum of the more refrangible part was obtained. From want of accurate adjustment of the focus, or from the motion of the star not being exactly compensated by the clock movement, or from atmospheric tremor, the spectrum, though tolerably defined at the edges, presented no indications of lines. Our other investigations have hitherto prevented us from continuing these...
Page 272 - The hydrogen line near G, wave-length 4340, is strong and sharply defined ; that at h, wave-length 4101, is more delicate, and there are faint traces of other lines in the violet. Among these lines there is one point of difference, especially well shown in a photograph where the slit was placed in a north and south direction across the trapezium ; the...
Page 271 - I have been giving attention to the nebula in Orion, with two objects in view. First, to ascertain whether any changes are taking place in that body, by making a series of photographs, to be compared in the future with a similar series ; and, second, to photograph the spectrum of the nebula in various parts, so as to see whether any new lines could be found, and also whether the composition is uniform throughout.
Page 271 - In carrying out the second object two contrivances have been used ; first, a direct vision prism in the cone of rays from the objective before they had reached a focus, and second the two-prism spectroscope with which I have taken photographs of stellar spectra for some years past. During the month of March I have made two good phototrapbs with each of these arrangements.
Page 272 - X 4340, is of the same length as the slit, and where it intersects the spectrum of the trapezium stars, a duplication of effect is visible. If this is not due to flickering motion in the atmosphere, it would indicate that hydrogen gas was present even between the eye and the trapezium.
Page 264 - I had already constructed a silvered glass reflector of 15J inches aperture, which was commenced in 1858, and had taken with it many hundreds of photographs of the Moon. But as the mounting had been contrived for lunar photography and to avoid the Moon's motion in declination, the instrument was not suitable for the spectroscopic work contemplated. A reflector of twenty-eight inches aperture was therefore commenced in 1866, and in 1871 it was ready for use.
Page 269 - ... hypothesis, and it is this very condition of affairs that gives hopes of results valuable in their bearing on terrestrial chemistry and physics. In the photographs of the spectrum of Vega there are eleven lines, only two of which are certainly accounted for, two more may be calcium, the remaining seven, though bearing a most suspicious resemblance to the hydrogen lines in their general characters, are as yet not identified. It would be worth while to subject hydrogen to a more intense incandescence...
Page 266 - Aquilse and Venus, and sent a note concerning them to this Journal. Since that time Dr. Huggins has pursued the subject actively in spite of the London atmosphere, and has attained very fine results, which I had the pleasure of seeing at his observatory last spring. These he is preparing to publish shortly. In my observatory photographs have been taken of the spectrum of Vega, Arcturus, Capella, a Aquilae, Jupiter, Mars, Venus, the Moon, etc.

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