. The microscope; an introduction to microscopic methods and to histology. Microscopes. 126 DRAWING WITH THE MICROSCOPE \_CH. V. Fig. 113. One of the latest and best forms of the Abbe Camera Lueida (Bausch & Lomb Optical Co. ). § 59 and the prism loosened and raised or lowered to the proper level ; but in doing this one should avoid setting the prism obliquely to the mirror. In the latest and best forms of this camera lueida special arrange- ments have been made for raising or lowering the prism so that it may be used with equal satisfaction on oculars with the eye-point at differ- ent lev
. The microscope; an introduction to microscopic methods and to histology. Microscopes. 126 DRAWING WITH THE MICROSCOPE \_CH. V. Fig. 113. One of the latest and best forms of the Abbe Camera Lueida (Bausch & Lomb Optical Co. ). § 59 and the prism loosened and raised or lowered to the proper level ; but in doing this one should avoid setting the prism obliquely to the mirror. In the latest and best forms of this camera lueida special arrange- ments have been made for raising or lowering the prism so that it may be used with equal satisfaction on oculars with the eye-point at differ- ent levels, and the prism is hinged to turn aside without disturbing the mirror. One can determine when the camera is in a proper position by looking into the microscope through it. If the field of the microscope appears as a circle and of about the same size as without the camera lueida, then the prism is in a proper position. If one side of the field is dark, then the prism is to one side of the center ; if the field is consid- erably smaller than when the prism is turned off the ocular, it indicates that it is not at the correct level, i. e., it is above or below the eye- point. § 183. Arrangement of the Mirror and the Drawing Surface. —The Abbe camera lueida was designed for use with a vertical micro- scope (Fig. 109). On a vertical microscope if the mirror is set at an angle of 450, the axial ray will be at right angles with the table top or a drawing board which is horizontal, and a drawing made under these conditions will be in true proportion and not distorted. The stage of most microscopes, however, extends out so far at the sides that with a 450 mirror the image appears in part on the stage of the microscope. In order to avoid this the mirror may be depressed to some point below 450, say at 400 or 35°(Fig. 114). But as the axial ray from the mirror to the prism must still be reflected horizontally, it follows that the axial ray will no longer form an angle of 90 degrees
Size: 2228px × 1122px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1900, booksubjectmicrosc, bookyear1901
