. A text book of physics, for the use of students of science and engineering . the principal focus of O, so that the rayslemerge from O parallel, and also are very nearly parallel to the axis iscoming [of the tube. The function of theI reversed telescopic system EO[thus to render the rays,from a wide field, nearly parallel tothe axis of the tube. If the eyewere to look through O, a verymuch diminished image would beseen. The function of the telescopicsystem OE at the lower end ofthe tube is to produce a magnifi-cation, which in practice a littlemore than compensates for thediminution produced
. A text book of physics, for the use of students of science and engineering . the principal focus of O, so that the rayslemerge from O parallel, and also are very nearly parallel to the axis iscoming [of the tube. The function of theI reversed telescopic system EO[thus to render the rays,from a wide field, nearly parallel tothe axis of the tube. If the eyewere to look through O, a verymuch diminished image would beseen. The function of the telescopicsystem OE at the lower end ofthe tube is to produce a magnifi-cation, which in practice a littlemore than compensates for thediminution produced by the uppertelescope. The total magnificationof the two systems is about 1|. Before the rays from O come toa focus to form a real image, the45° prism P2 is interposed, whichrenders the rays horizontal andalso produces a final rectificationof the image ab, so that theimage ab seen on looking throughE is erect. There is always somearrangement of gearing to enablethe tube with the upper prism P1to be rotated in order to enablethe observer to look out in anydesired a
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Keywords: ., bookcentury1900, bookdecade1910, bookpublishe, booksubjectphysics
