The Astrophysical Journal, Volume 23University of Chicago Press, 1906 "Letters to the Editor" issued as Part 2 and separately paged from v. 148, 1967. Beginning in 2009, the Letters published only online. |
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absorption band Ångström angular aperture aperture apparatus appear asteroids Astrophysical Journal atmosphere atom axis bolometer bright broaden camera column comparison components corona curve determined diameter DIAPHRAGM discharge-tube disk distance double East West East eclipse effect electrons equations exposure faint film flocculi fluorite focal length fourth-type Fraunhofer lines give given grating Guelma hydrogen hydrogen lines instrument intensity investigations Lick Observatory light lines luminosity magnetic magnitude mean measures method mirror motion mounted nebula O-I O-I observations obtained optical orbit parallaxes period photographic plate photosphere position pressure prisms Professor radial velocity radiation radius region reversal ring rotation Rowland screw selenium slit solar spectra spectrograph spectroheliograph spectroscope spot spectrum stars structure sun-spots Sun's taken temperature tion tube ultra-violet variable Variable Stars velocity Wave wave-length West East West Yerkes Observatory Zeeman effect ΙΟ μμ
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Page 315 - Total Eclipse of the Sun, May 18, 1901. Reports on the Dutch Expedition to Karang Sago, Sumatra, N '. 4 : Heat Radiation of the Sun during the Eclipse", by WH JULIUS.
Page 238 - Thus the induced current is at all times directly proportional to the total change in the number of magnetic lines of force passing through the circuit. Besides, every induced current persists so long as the new number of lines of magnetic force through the circuit is not allowed to change. In the case of any particular ring K, the value of the current is it t . • v , , t . Hence aik = - = -j— , which shows that -j~- is a constant.
Page 53 - Yerkes refractor. As stated in this paper, the most satisfactory form of spectroheliograph is that in which the instrument is moved as a whole, while the image of the Sun and the photographic plate are stationary. The first spectroheliograph of this type was constructed in 1893, from Mr. Hale's general design, by Toepfer, of Potsdam, and employed in some attempts to photograph the solar corona without an eclipse, from the summit of Mount Etna.
Page 11 - It is only necessary to arrange the daily program of observations so that the spectroheliograph, which requires the finest definition, is used during the period when the seeing is best. Photographic work on the spectra of sun-spots follows, and after this is completed the conditions are entirely satisfactory for various other observations, such as holographic work on the absorption of the solar atmosphere, etc. The photographs reproduced in Plate VIII will give an idea of the results obtained with...
Page 245 - Experiment leaves this in doubt. 7. The shift of analogous lines due to different elements of the same general nature, elements of the same Mendelejeff group, should increase with increase of atomic weight, since the strength of an atom's magnetic field probably is an increasing function of atomic weight. 8. Any group of lines due to a given element, such as a series, that gives Zeeman effects proportional to the wave-length, should shift under pressure in the same ratio. 9. Ordinarily, lines of...
Page 392 - Fig. 140, is in the form of a guide which is bolted to the back of the lathe. It can be set at any desired angle with the axis of the lathe, the limit usually being a taper of about three inches per foot. The guide is graduated so Fig.
Page 32 - I have been able to make out yet, there is no difference as regards these fine lines between one spot and another. I have never yet seen any evidence of displacement in them due to motion, no " lumpiness" nor want of smoothness in them. When seeing is at the best, and everything favourable, close attention enables one to trace nearly all these lines out beyond the spot and its penumbra. But they are so exceedingly faint on the Sun's general surface that usually they cannot be detected outside the...
Page 202 - The pressure and purity of the gases, the shape and character of the discharge-tube, the material of the electrodes, and the time of exposure are all factors which have undergone investigation. METHODS OF MEASUREMENT The methods used were two in number. The values of all the lines were first obtained by the two-slit method, and these values were then checked by obtaining the stronger lines in the second spectrum and comparing their positions with known iron lines in the first spectrum. For this last...
Page 279 - ... whose phenomena would become predictable if we knew both the original quantity and kind of this heat; how it affects the constituents of the atmosphere on its passage earthward; how much of it reaches the soil; how, through the aid of the atmosphere, it maintains the surface temperature of this planet; and how in diminished quantity and altered kind it is returned to outer space.
Page 65 - X 5461 appears to be quite unique in the possession of its satellites. Of the hundreds of lines examined, not another one has been observed having so complex a structure when so feebly excited. PLUCKER TUBE SPECTRA Rarefied gases moderately excited show narrow lines of the simplest structure, but with a heavy current or capacity in parallel — if the 1 Comptes Rendus, 140, 848-851, March 27, 11505.