202 



SUMMARY OF CURRENT RESEARCHES RELATING TO 



Leitz' Thermometer Microscope. — This apparatus (fig. 22) has 

 been made by the Wetzlar firm to the design of Fridtjof Hansen, and is 

 intended for the accurate reading of a thermometer. The nickelled 

 draw-tube is attached to a black lacquered stand, whose foot ends in 



Fig. 22. 



two incisions into which thermometers of different sizes may be clamped 

 by means of a holder acting on a spiral spring. The instrument is 

 fitted with a micrometer eye-piece and a low-power achromatic 

 objective. 



Leitz' New Cheap Stand. — In this stand, No. III. in catalogue 

 (fig. 23), economy has been especially studied. It is intended for 

 ordinary laboratory use, and can take high-power dry objectives, but not 

 immersion lenses. The coarse adjustment is by rack-and-pinion , and 

 the fine by micrometer-screw. The mirror is plane and concave. The 

 price of the stand, with the two adjustments and the revolving diaphragm 

 disc, in mahogany case, is 21. 10s. 



(3) Illuminating and other Apparatus. 



Driiner's New Magnifying Stereoscopic Camera.* — Dr. Driiner 

 prefaces the description of his apparatus by a historical sketch of 

 stereomicroscopy. 



His instrument (fig. 24), which consists of a double aluminium 

 camera encased in black leather, has, at its reduced lower end, the slide 

 apparatus for the reception of the twin objectives. The optical axis 

 of each of the two combined cameras coincides with the optical axis 

 of one of the two systems of the twin objectives, and stands perpendicu- 

 larly on the plane of one of the two reception screens v. These screens 



• Zeitschr. wies. Mikr., xvii. (1900) pp. 281-94 (1 pi. and 1 fig.). 



