Metallurgy; an introduction to the study of physical metallurgy . nt ofthe source of Mght would be disturbed. By leaving the body-tube approximately in one position and effecting the otheroperations by moving the stage this frequent re-adjustment isavoided. The movable stage also has the advantage that awider gap can readily be provided between stage and objective,and this allows of the use of long-focus objectives and of thickspecimens of metal. In this type of metallurgical microscope the usual practice isto employ a special vertical illuminator, which is screwed tothe bottom of the body-tub
Metallurgy; an introduction to the study of physical metallurgy . nt ofthe source of Mght would be disturbed. By leaving the body-tube approximately in one position and effecting the otheroperations by moving the stage this frequent re-adjustment isavoided. The movable stage also has the advantage that awider gap can readily be provided between stage and objective,and this allows of the use of long-focus objectives and of thickspecimens of metal. In this type of metallurgical microscope the usual practice isto employ a special vertical illuminator, which is screwed tothe bottom of the body-tube, the objective being screwed tothe illuminator. The objective differs from most lenses of thiskind only in being mounted in a very short mount or tube inplace of the longer ones ordinarily employed. This allows thereflector of the vertical illuminator to come quite close to therear surface of the lens, and this tends to minimise the internalscattering of light which is apt to render images obtained fromimproperly adjusted illuminators weak or milky. PLATE Fig. 4.
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectmetals, bookyear1922
