. The microscope; an introduction to microscopic methods and to histology. Microscopes. CH. If] LIGHTING AND FOCUSING 51 one made of metal with a slit-opening covered with an oblong cover- glass is more satisfactory, as the source of light is more restricted. Very excellent results may be obtained, however, with the ordinary bed-room lamp furnished with the usual glass chimney. The new acetylene light promises to be . excellent for micro- scopic observation and for photo-micrograph}-. (See under photo- micrography.). Fig. 53. 1. Lamp with slit-opening in metal chimney. 2. Bull's eye on separat
. The microscope; an introduction to microscopic methods and to histology. Microscopes. CH. If] LIGHTING AND FOCUSING 51 one made of metal with a slit-opening covered with an oblong cover- glass is more satisfactory, as the source of light is more restricted. Very excellent results may be obtained, however, with the ordinary bed-room lamp furnished with the usual glass chimney. The new acetylene light promises to be . excellent for micro- scopic observation and for photo-micrograph}-. (See under photo- micrography.). Fig. 53. 1. Lamp with slit-opening in metal chimney. 2. Bull's eye on separate stand. 3. Screen showing image of flame. Whenever possible the edge of the flame is turned toward the microscope, the advantage of this arrangement is the great brilliancy, due to the greater thickness of the flame in this direction. § 94. Mutual Arrangement of Lamp, Bull's Eye and Micro- scope.—To fulfill the conditions given above, namely, that the object be illuminated by the image of the source of illumination the lamp must be in such a position that the condenser projects a sharp image of the flame upon the object (Fig. 53), and only by trial can this posi- tion be determined. In some cases it is found advantageous to discard the mirror and allow the light from the bull's eye to pass directly into the condenser. This method is especially excellent in photomicro- graphy (see Ch. VIII). § 95. Illuminating the Entire Field.—With low objectives and large objects, the entire object might not be illuminated if the above method were strictly followed ; in this case turn the lamp so that the flame is oblique, or if that is not sufficient, continue to turn the lamp until the full width of the flame is used. If necessary the. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Gage, Simon Henry, 1851-1944. It
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