216 SUMMARY OF CURRENT RESEARCHES RELATING TO 



MICROSCOPY. 



A. Instruments, Accessories, &c* 



(!) Stands. 



Watson and Sons' Club Microscope.f — In appearance this instru- 

 ment (fig. 25) is very similar to the Van Heurck model manufactured by 

 Watson and Sons, but the idea has been to simplify the general details, 

 and to provide in it such mechanical conveniences as are desired by an 

 amateur, omitting the refinements that are only required by and of im- 

 portance to the expert and critical worker. 



The tripod foot has a spread of !) in. ; the stage is 5 in. in diameter, 

 and has mechanical and rotary movements ; the substage has rackwork 

 to focus and screws to centre, and can be turned aside from the optic 

 axis with the apparatus contained in it when desired. The instrument is 

 of full size, measuring in height 12| in. when racked down. 



Watson and Sons' Praxis Penological Microscope.^ — This is a 

 Penological Microscope (fig. 26) of continental model, with the horse- 

 shoe foot and the upright pillar cast in a solid piece. The body contains 

 an analyser prism and a Klein's quartz plate. The polariser, which is 

 carried in a plate beneath the stage, can be turned aside from the optic 

 axis when desired. The coarse-adjustment is by diagonal rack-and- 

 pinion, and the fine-adjustment is Watsons' standard lever pattern. 



Watson and Sons' School Microscope, 1905 Modeli — Several 

 modifications have been made in this instrument (fig. 27). The foot 

 and the upright are cast in one solid piece, also the stage and the limb 

 are cast solid. The stage has been fitted with an ebonite covering, and 

 although the instrument is made with a coarse-adjustment by diagonal 

 rack-and-pinion only, provision has been made for the subsequent 

 addition of fine-adjustment should it be desired. 



Reichert's New Large Mineralogical Stand. || — This instrument 

 (fig. 28) differs from the one described in the Journal, 1905, p. 245, in 

 that the limb is altered to the handle form, and the fine-adjustment 

 located therein for greater security. 



* This subdivision contains (1) Stands ; (2) Eye-pieces and Objectives ; (3) 

 Illuminating and other Apparatus ; (4) Photomicrography ; (5) Microscopical 

 Optics and Manipulation ; (6) Miscellaneous. 



+ W. Watson and Sons' Catalogue, 1906, p. 36. 



t Tom. cit., p. 84. § Tom. cit. ; p. 68. 



|| Eeichert's Special Catalogue, 1905-1906, p. 11. 



