. The microscope; an introduction to microscopic methods and to histology. Microscopes. 200 THE PROJECTION MICROSCOPE CCh. VI (8) For all but the highest powers a substage condenser is not needed; and one can hght objects up to 50 or 60 mm. in diameter if the object is placed in the right position in the cone of Ught (fig. 124). (9) For objectives of higher power than 4 mm. a substage con- denser should be used, and if an ocular is used as well as an objective then the substage condenser is advantageous for powers above 8 mm. equivalent focus. For lighting see § 104, 107, Fig. 121. iLLUM
. The microscope; an introduction to microscopic methods and to histology. Microscopes. 200 THE PROJECTION MICROSCOPE CCh. VI (8) For all but the highest powers a substage condenser is not needed; and one can hght objects up to 50 or 60 mm. in diameter if the object is placed in the right position in the cone of Ught (fig. 124). (9) For objectives of higher power than 4 mm. a substage con- denser should be used, and if an ocular is used as well as an objective then the substage condenser is advantageous for powers above 8 mm. equivalent focus. For lighting see § 104, 107, Fig. 121. iLLUMiNATrNG Objects of Various Sizes in Micro-projection WITH THE Main Condenser Only. (From Optic Projection). The object must be put in the cone of light at a point where it will be fully illuminated. For high powers it will be at or very near the focus (/). For larger objects and low powers at 2 or 3, or even closer to the condenser face. Arc Supply The right-angled carbons of the arc lamp. Li Li The first and second elements of the triple condenser. Waler Cell The water cell for absorbing radiant heat. It is in the parallel beam between the first and second elements of the condenser. Axis The principal optic axis on which all the parts are centered. (10) One of the most important points is to have a very white screen. A cloth or wall screen painted with Artist's Scenic White gives a very perfect screen which does not yellow with age, and its primitive whiteness is restored by an occasional coat of fresh white. Semi-mirror screens are successful orily in narrow rooms. For short screen distances (i or 2 meter screen distances) white cardboard or a sheet of very white bristol board gives excellent results. The apparatus, in contrast to the screen, should be dull black. § 312a. Masks for demonstration slides. —The paper to use should allow the red and orange to pass, but cut off the green-blue end of the spectrum. An. Please note that these images are extracted from scanned pag
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