The Astrophysical journal . 14 th September 1906 R 1-= nearlv 2 PENUMBRA IN SUN-SPOTS 275 small size of the picture. The breadth of the filaments, especiallyat their sharper end, is, on the enlarged image, only two or threetenths of a millimeter. The same object on the image at the focus ofthe telescope must therefore have a size of only one or two hundredthsof a millimeter. It does not seem that so narrow lines can be printedwithout confusion on a silver-bromide film. Consequently, wherethe filaments are shining more brightly their confusion causes a largepatch of sensitive film to be blacken
The Astrophysical journal . 14 th September 1906 R 1-= nearlv 2 PENUMBRA IN SUN-SPOTS 275 small size of the picture. The breadth of the filaments, especiallyat their sharper end, is, on the enlarged image, only two or threetenths of a millimeter. The same object on the image at the focus ofthe telescope must therefore have a size of only one or two hundredthsof a millimeter. It does not seem that so narrow lines can be printedwithout confusion on a silver-bromide film. Consequently, wherethe filaments are shining more brightly their confusion causes a largepatch of sensitive film to be blackened. At points where the sharp-ening of the filaments renders their light both narrower and fainter,their confusion prevents any action of the light to be marked on thefilm. The granules of the photosphere are very small, their diametervarying from 3 to 1 or a little under 1, and yet they come outdistinctly where the filaments of the penumbra appear only in is true; but the diameter of these granules, even those
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectspectru, bookyear1895
