The microscope; an introduction to microscopic methods and to histology . itions will be in true proportion and not distorted. The stage ofmost microscopes, however, extends out so far at the sides that witha 450 mirror the image appears in part on the stage of the order to avoid this the mirror may be depressed to some point below450, say at 400 or 35°(Fig. 114). But as the axial ray from the mirrorto the prism must still be reflected horizontally, it follows that the axialray will no longer form an angle of 90 degrees with the drawing sur-face, but a greater angle. If the mirro
The microscope; an introduction to microscopic methods and to histology . itions will be in true proportion and not distorted. The stage ofmost microscopes, however, extends out so far at the sides that witha 450 mirror the image appears in part on the stage of the order to avoid this the mirror may be depressed to some point below450, say at 400 or 35°(Fig. 114). But as the axial ray from the mirrorto the prism must still be reflected horizontally, it follows that the axialray will no longer form an angle of 90 degrees with the drawing sur-face, but a greater angle. If the mirror is depressed to 350, then theaxial ray must take an angle of no° with a horizontal drawing surface(see the geometrical figure Fig. 114, A). To make the angle 900 again,so that there shall be no distortion, the drawing board must be raisedtoward the microscope 200. The general rule is to raise the draw-ing board twice as many degrees toward the microscope as themirror is depressed below 45°. Practically the field for drawing CH. V\ DRA WING WITH THE MICROSCOPEB 127. Fig. 114. C Abbe Camera Lucida in position to avoid distortion. Fig. 114.— The Abbe Camera Lucida with the mirror at 35°. Axis, Axis. Axial ray from the microscope and from the drawing surface. A. B. Drawing surface raised toward the microscope 20°. Foot. The foot or base of the microscope. Mirror with quadrant {Q). The mirror is seen to be at an angle of 35°. Ocular. Ocular of the Microscope. P. P. Drawing pencil and the cubical prism over the ocular. W. Wedge to support the drawing board. A. Geometrical figure of the preceding, showing the angles made by theaxial ray with the mirror and the necessary elevation of the drawing board toavoid distortion. From the equality of opposite angles, the angle of the axial rayreflected at 35° must make an angle of 110° with a horizontal drawing board. Theboard must then be elevated toward the microscope 20° in order that the axial raymay be perpendicular to it, and
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectmicrosc, bookyear1901
