ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 



G13 



condenser is easily removable, as, whon using low magnifications, it is 

 advisable to work with the lower condenser lens only. A sliding sleeve, 

 within which the polariser may be revolved by means of a lever, is 

 situated below the revolving and graduated stage, 



Zeiss' Small Model Polarising Microscope.* — This stand (fig. 117), 

 indexed as VI b , is one of Zeiss' smaller models adapted for work with 

 polarising apparatus. It bears a revolving stage (diam. 80 mm.) with 

 a graduated peripheral scale. A centring appliance for objectives is 

 situated on the lower extremity of the tube. Objectives of the highest 

 power can be used, and the stage can bo completely rotated. 



Messter's Attachable Mechanical Stage.f — M. Marpmann highly 

 praises this accessory for its cheapness and convenience. The object- 

 slide, which fits into a space of suitable size, is secured by two clamps. 

 The stage itself is easily attached to any Microscope : the upper screw 

 fits into a hole of the table and the trigger-shaped part on the right is 

 secured to the pillar, so that the stage is rigid in all positions. Of 

 the two screws which control the stage motions the lower imparts a per- 

 pendicular movement from front to rear within limits of 30 mm., and 

 the front one a lateral movement within a range of 50 mm. These 

 dimensions serve for preparations of large size. Positions are noted by 

 means of two scales which are easily read to 0* 1 mm. 



Fig. 118. 



Huntingdon's Tilting-stage for Holding and Adjusting Minerals. 

 —This apparatus (fig. 118), made by Messrs. E. and J. Book, consists 

 of a pair of brass plates which grip a ball, held in two circular holes 

 cut in the plates. The ball is surmounted by a small stage, and from 

 its inferior aspect projects a rod by which the specimen is oriented. By 



* Catalogue, English edition, 1902, pp. G'J-. r >. 



t Zeitsch. f. angew. Mikr., ii. (11)01) pp. 230-4 (1 fig.). 



