. A practical treatise on the use of the microscope, including the different methods of preparing and examining animal, vegetable, and mineral structures. Microscopes; Microscopy. 198 USB OF THE MICEOSCOPE. the small condenser, before described at page 123; this, gene- rally speaking, is a double convex lens of two or three inches. Fig. 126. focus, either supported on a separate foot, or else attached to some Immovable part of the stand of the microscope, and should be so placed that the rays of light from the large condenser may fall upon it. These rays being slightly con- vergent, and fallin
. A practical treatise on the use of the microscope, including the different methods of preparing and examining animal, vegetable, and mineral structures. Microscopes; Microscopy. 198 USB OF THE MICEOSCOPE. the small condenser, before described at page 123; this, gene- rally speaking, is a double convex lens of two or three inches. Fig. 126. focus, either supported on a separate foot, or else attached to some Immovable part of the stand of the microscope, and should be so placed that the rays of light from the large condenser may fall upon it. These rays being slightly con- vergent, and falling upon a plano-convex lens, will be ren- dered more convergent, and brought to a focus, F, upon the object, C, as seen in fig. 126, where L represents the lamp, D E the large condenser, and A B the smaller. The small condenser answers uncommonly well for daylight, for, in this case, the rays being parallel, they will be made to converge and be brought into focus upon the object. This mode of illuminating an opaque object appears to have been first contrived by Hooke, in 1675, for, in his Micrographia, plate 1, the same arrangement is represented as the one above described, but, instead of a large condenser, a globe of glass full of water was used by him. The other mode of illuminating an opaque object by oblique light is that by the side reflector, the invention of Mr. Ross: it consists of a concave oblong silver cup, described at page 127, which is attached to some immovable part of the stage or stand of the instrument, and is supplied with a sliding arm and a ball and socket joint for adjustment, so that it may be used for an opaque object either placed on the stage, or held by the forceps; the mode is as foUows:—. 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 Quekett, John, 1815-1861. London, H. Baill
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