The microscope and its revelations . hat the Educational ilicroscope for which they invited competition (§ 31),should be furnished with such a power. This recommendation having beenadopted, the instrument selected has been specially fitted for the class ofobjects above aUuded-to. N 2 180 MANAGEMENT OE THE MICEOSCOPE. which it is desired to illuminate them. If the object bemounted in a slide of glass or wood, upon a large opaquesurface, the slide must be laid on the stage in the usualmanner, and the object brought as nearly as possible intoposition by the eye alone (§ 84). If it be not so mount
The microscope and its revelations . hat the Educational ilicroscope for which they invited competition (§ 31),should be furnished with such a power. This recommendation having beenadopted, the instrument selected has been specially fitted for the class ofobjects above aUuded-to. N 2 180 MANAGEMENT OE THE MICEOSCOPE. which it is desired to illuminate them. If the object bemounted in a slide of glass or wood, upon a large opaquesurface, the slide must be laid on the stage in the usualmanner, and the object brought as nearly as possible intoposition by the eye alone (§ 84). If it be not so mounted, itmay be simply laid upon the glass stage-plate, resting againstits ledge; and the diaphragm-plate must then be so turned, asto afford it a black back-ground. Eor all ordinary purposes,a piano- or double-convex lens, of about 1| inch diameter,and 2 inches focus, either mounted upon a separate stand (asin Eig. 45), or so attached by a jointed support to the Micro-scope itself as to admit of being placed in any required Fig. Arrangement of Microscope for Opaque Objects. position, will ansAver extremely well as a Condenser.—If Day-light be employed, the microscope should be so placed thatthe strongest light may fall obhquely upon the stage, and pre-ferably from the left hand side ; there will then be no difficultyin so disposing this condenser, as to afford an illuminationsufficient for almost any kind of object, provided the quahtyof the light itself be good. Direct sunlight cannot be hereemployed, without the production of an injurious glare, andthe risk of burning the object; but the sunlight reflected from a DIEECTIOX OE ILLUiyilNATIOy FOR OPAQUE OBJECTS. ISl bright cloud is tlie best light possible. The condenser shouldalways be placed at right angles to the direction of theilluminating rays, and at a distance from the object -NThichwill be determined by the size of the surface to be illuminatedand by the kind of light reqmred. If the magnifying poweremployed be
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