120 



SUMMARY OF CURRENT RESEARCHES RELATING TO 



withjhigh-power objectives, and it possesses the convenience of a large 

 field-lens, viz. 5/8 in. diam. The mounting, as shown in illustration, 

 is convenient in form ; the iris diaphragm has immediately above it 

 thej Society's objective thread into which the optical portion of the 

 condenser screws. The tube surrounding the iris diaphragm is divided 

 to enable the aperture at which the condenser may be working to be 

 known ; a carrier is also provided for coloured glasses, dark ground 

 stops, &c. The top lens of the condenser can be removed for work 

 with low-power objectives. 



Fig. 23. 



Fig. 24. 



Fig. 24 represents an oil-immersion condenser by the same firm, 

 having a total aperture exceeding 1*3 and an aplanatic aperture of 1*27. 

 It will be noticed that it attains a very high degree of aplanatism, and 

 this is brought about by the use of a triple back correcting lens which 

 is 6/10 in. diam. ; its power is 1/4 in. It also can be used dry for 

 medium and low-power objectives by removing the top lens, when its 

 power becomes 2/7 in. and the aperture 0*60 N.A. This optical part is 

 also fitted with the Society's screw, and is supplied in a mount similar 

 to the condenser above described, the iris diaphragm, however, being 

 divided to suit the different optical system. 



Reichert's New Projection Apparatus. — » This apparatus (fig. 25) 

 is fitted with an optical bench mounted on a solid board, and can be 

 used with the ordinary type of adjustable Continental Microscope. The 

 light-source is either a hand-feed arc lamp, or a Schuckert's automatic 

 self-regulating projection lamp, in metal box lined with asbestos. The 

 3-lensed 150 mm. diameter condenser system contains a water-chamber 

 affording a sufficient protection to the preparations against prolonged 

 heating. The frame for the reception of the slides is U by 12 cm., and 

 the projection-objective, adjustable by rack-aud-pinion, is of about 12 cm. 

 focus. There is an adjustable foot-plate to which is fastened the 

 Microscope stand. 



The apparatus may also be equipped with a special projection- 

 Microscope stand which very much facilitates the working. The coarse 

 adjustment is then by rack-and-pinion, j^ermitting an especially long 

 movement for the long-focussed objective ; the fine adjustment is by 

 micrometer screw. The tube is chosen of such a width that the light- 

 cone of the weakest projection-objective is fully utilised. For the pro- 

 jection-ocular an adjustable draw-out tube is employed. The object- 



