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®n a Simple Zan\\ fllMcroecope-* 



Bv C. RoussELET, F.R.M.S. 



I DESIRE to bring to your notice a small tank microscope 

 designed for the purpose of rapidly looking over pond water 

 and weeds, collected at a day's excursion, and placed in a 

 small parallel-sided window aquarium. 



The instrument hardly needs description ; its working will be 

 readily understood by reference to the figure. 



One of Zeiss' aplanatic lenses is carried on a jointed arm, 

 which moves parallel to the side of the tank, and the lens is 

 focussed by means of a rack and pinion, the whole being fixed 

 to the upper left-hand corner of the tank by means of a screw 

 clamp. 



The following points will recommend themselves to those who 

 are in the habit of looking at their captures with the pocket lens 

 in the ordinary way : — 



When an object of interest is found, it can be followed with the 

 greatest ease and taken up with a pipette, both hands being free 

 for this operation. 



* From "The Journal of the Quekett Microscopical Society." 



Journal of Microscopy and Natural Science. 



New Series. Vol. III. 1890. i 



