ZOOI.iHJY AN'IJ I'.OTANV, MICROSCOPY, KTC. 233 



The object-carrier eno-ages in a very exact gearing, wliich secures that the 

 optical axis of the ]\Iicroscope passes exactly throngh the rotation-centre 

 of the stage. 



When used for optional centring and for Fedorow's stage (fig. 9), 

 the object-carrier is removed, and the objective is fixed l)y tlie pinch- 

 grip ji? : the Bertrand lens B now passes to A. To fix the Fedorow stage 

 the Microscope stage is brought to zero (Vernier n-^) ; the apparatus is 

 placed so that the axis of rotation i/i is perpendicular to the plane of 

 symmetry, and the limb is on the right. By means of the fixation 

 screws this axis can be set parallel to the corresponding thread of the 

 network without the necessity of turning the stage of the Microscope. 

 The rings and the central lens V are in the same plane. The height of 

 the Microscope stage will be regulated by the consideration that the 

 tube s'hould be supported by its middle part. The polarizing and 

 analyzing nicols are movable ; the divisions and 90°, on their gradua- 

 tions, correspond to the fuiidamental positions of the principal sections, 

 crossed or pai'allel, according to the plane of symmetry of the Microscope 

 or its perpendicular. The stage, mounted on a guide-block, can be 

 raised or lowered for the use of long frontal distances, and is firmly and 

 solidly fixed by help of the knob /. iVt the height of the focal plane of 

 one of the negative oculars the tube is pierced with an opening q at 

 4,')'' of the plane of symmetry analagous to that which is situated above 

 the clip ;;. This aperture can be screened if desired ; a similar opening 

 is pierced in the corresponding ocular. The displacements of the ocnlar 

 apparatus, which is controlled by a I'ackwork d, can be read off on a 

 graduation contrived on the tul)e. In the opening A a Bertrand lens 

 can be inserted whose focus is independent of the position of the tube. 

 The condenser can be removed if desired. The stage carries two verniers, 

 //j and Wo, whose graduations are in the same sense, and whose zeros are 

 distant by loS", in addition to a mark tk, whose index is at 45° from 

 the zero of n^ The adjustment is then finished, and the apparatus 

 is ready for work. 



The new model (fig. 10) of Fedorow's stage is constructed as follows : 

 The axis ?/j is a part of the same metal piece as that forming the 

 exterior disk x which carries the vernier m. The rotations of the axis //i 

 are measured on _/, whose limit is doubly divided from o to 180°. A 

 second ring //r, graduated completely can tnrn on the disk x, and carries 

 the trunnions of a second axis H, which is usually placed perpendicular 

 to //p and which is served by the vernier m. The central disk t can be 

 sloped l)y rotation around H, and its inclinations measured either with 

 the circular arcs W mounted on hinges on the ring y., perpendicularly to 

 the axis H, or Ijy sight on the borders of the disk t and read off on the 

 vernier y, after the axes H and /y^ have been brought into coincidence 

 at the zero of the vernier m. The mount of the central glass V can lie 

 turned in the disk t, and its position is noted by the divisions of /. 

 This lens bears a cross whose centre is at • 15 mm. Ijelow the crossing- 

 point of the axis y^ and H. This point is also common to the I'otation 

 axes of the disks y^ and t. When the adjustment is once finished the 

 Microscope axis should also pass through this point. 



