. A Manual of botany : being an introduction to the study of the structure, physiology, and classification of plants . Botany. 770 COMPOUND r and in 949 it is mounted. The woodcuts are exactly wne-half the real size, and give a good idea of the instrument, a detailed description of which is not required. In fig. 950 a representation is given of one of Smith and Beck's microscopes for students. A is the brass stand, sup- ported firmly on three feet, and having two upright flat cheeks, to the top of which the stage-plate, d, is fixed. Into the stage-plate is screwed an upright round
. A Manual of botany : being an introduction to the study of the structure, physiology, and classification of plants . Botany. 770 COMPOUND r and in 949 it is mounted. The woodcuts are exactly wne-half the real size, and give a good idea of the instrument, a detailed description of which is not required. In fig. 950 a representation is given of one of Smith and Beck's microscopes for students. A is the brass stand, sup- ported firmly on three feet, and having two upright flat cheeks, to the top of which the stage-plate, d, is fixed. Into the stage-plate is screwed an upright round tube, to which is attached an open tube, g, in which the body of the instrument, fh, slides. By moving the body up and down in this tube, the coarse adjust- ment is effected, and when the instrument is brought near to the object on the stage-plate, d, a finer adjustment is made by means of the screw with the milled head, e, which either raises or depresses the part by which g is attached to the up- right tube. The mirror is re- presented at h, supported on trunnions, and capable of mo- tion upwards or downwards, so as to reflect the light on the object placed on the stage- plate ; c' is the diaphragm or stop, or perforated plate attached to the stage, with the view of shutting ofi' the extreme rays of light. The object-glass or objective is placed at the lower end of the instrument, /, and the eye-piece or ocular at the upper part, h. In fig. 951 a diagram is given to explain the mode in which the compound microscope acts. In this figure, o is the object, above which is seen the triple achromatic object-glass or objective, consisting of three achromatic lenses, which are combined in one tube ; c c is the eye-piece or ocular, consisting of two plano-convex lenses, one at e, being the eye-glass, and the other at c, the field-glass. Three rays of Fig. 950, Smitli and- Beck's compound microscope for students. A, brass stand, sup- ported on three feet; 6, mirror supported on trunni
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Keywords: ., bookcentury1800, bookdecade1870, booksubjectbotany, bookyear1875
