The London, Edinburgh and Dublin philosophical magazine and journal of science . Figr. —3 to half the intensity at the centre. As will be seen from theexpression for Ti? the intensity increases very rapidly from Focal Plane of a Telescope with Circular Aperture. 21 the rim towards the centre ; and from that for Ic, the decreasetakes place very rapidly as we pass from the rim the variation of intensity is greatest near the rim, butthe change does not take place abruptly; the intensity fadesaway gradually in the neighbourhood of the rim, as illustratedin the accompanying diagra
The London, Edinburgh and Dublin philosophical magazine and journal of science . Figr. —3 to half the intensity at the centre. As will be seen from theexpression for Ti? the intensity increases very rapidly from Focal Plane of a Telescope with Circular Aperture. 21 the rim towards the centre ; and from that for Ic, the decreasetakes place very rapidly as we pass from the rim the variation of intensity is greatest near the rim, butthe change does not take place abruptly; the intensity fadesaway gradually in the neighbourhood of the rim, as illustratedin the accompanying diagram* (fig. 9). The full line is fora = co, and the dotted line for a = 40. The image of a luminous disk, as seen through a telescope,is thus not sharply defined at the geometrical rim, where thechange of intensity takes place continuously. If the intensityfor the limit of visibility be less than Ir, the image of the diskwill appear to a slight extent broadened. 7. Lines of Equal Intensity. For practical purposes it is sometimes convenient to drawthe lines of equal intensity. For a circ
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Keywords: ., bookcentury1800, bookdecade1840, booksubjectscience, bookyear1840
