Abbe's Drawing Camera: Latest modification (Figs, 49 and 50). (Zeitschr. f. wiss. Mikroskopie, Vol. II, p. 289), 1894). The camera is attached to the tube by means of the clamping ring K and the Abbe double prism is centred by means of the screws L and H. The brightness of the drawing surface and the microscopic image are respectively regulated by a cap R encasing the prisms, which is provided with a clear opening and 5 moderating glasses of varying
degrees of density and by an excentric disc B pivoted below the prisms, which is also provided with a clear opening and 5 moderating glasses.
In order to completely utilize the increased cone of emerging rays obtained with low magnifications the usual prism having in its silvering an aperture of 1 mm can quickly and conveniently be exchanged for another with an aperture of 2 min (Fig. 50).
The prism together with the moderating glasses may be turned aside about the vertical pin Z. into the position indicated by the dotted lines shown in Fig. 49. When the prism is made to return into its original position it is fixed by a catch, which is not externally visible. The size and other features of the mirror arc the same as with No. 44.