ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 



497 



divided into 360°. 

 Bertrand lens. 



On the front of the tube is a slit for receiving the 



Leitz' Mechanical Stage.*— This (fig. 89) is an improvement on 

 the earlier form noticed in this JournaLf It will be seen that the hori- 

 zontal pinion goes right through the stage and carries a milled head at 

 each end. The previous pattern had the screw-head only on the right- 

 hand. The two rectangular movements are fitted with scales and verniers. 

 The ranges are respectively 50 and 30 mm. 



Object-stage, with Sliding Measurement Adjustment.^— J. Tuz- 

 son and M. Herrmann have sought to produce a measuring apparatus 

 which should be accurate, easy to manage, and independent of the lens 



Fig. 89. 



system. The principle of their method consists in pushing the object 

 under the fixed cross-threads of the ocular by means of a specially con- 

 structed micrometer screw. The amount of the push-movement is 

 obtained by direct reading and without calculation. 



The general appearance of the apparatus is shown in fig. 90, and in 

 section in fig. 91. The rotatory object-stage A is of ordinary construc- 

 tion, and, by means of a hollow circular flange (conical in section), 

 works in the slide-rest B without play. This slide can be urged back- 

 wards and forwards in a straight line in a prism-groove of the ground 

 plate C, which is rigidly attached to the Microscope stand. The arrange- 

 ments are such that the Abbe illumination is unaffected, and the movable 



* Catalogue No. 41 (Mikroskope) 1905, pp. 83-4. 



t J.K.M.S., 1904, p. 105. 



% Zeitschr. wiss. Mikrosk. xxi. (1904) pp. 1S9-99 (4 figs.). 



Aug. 16th, 1905 2 L 



