II. OPIITHALMOLOGICAL. 785 



chamber moist, or for the infusion of gas. A small gas-flame, 

 which imparts heat to the adjoint-piece, serves as a heat conductor. 

 The Imperial and Royal Pathological and Anatomical 

 Institute of the University of Prague (Director, Pro- 

 fessor Edwin Klebs}. 



3668. Microtome. A circular knife is set revolving by a 

 turning-lathe. The preparations, which are embedded in a metal 

 case, are moved forward by a micrometer screw, and passed across 

 the edge of the rotating knife by a contrivance similar to that in a 

 dividing engine. 



The Imperial and Royal Pathological and Anatomical 

 Institute of the University of Prague (Director, Pro- 

 fessor Edwin Klcbs). 



3668*. 



IL OPHTHALMOLOGICAL APPARATUS. 



3669. Instruments for Extraction of Cataract. 



Dr. Adolph Weber. 



3669a. New Telescope and collection of metrical glasses, for 

 ophthalmology. A. Nachet, Paris. 



3669b. Artificial Eye, by Dr. Lfindolt. A. Nachet, Paris. 

 3669c. Fupillometer, by Dr. Landolt. A. Nachet, Paris. 

 3671. Fupilloxneter. Emil Stohrcr, Leipzig. 



3673. Hermann's Blemmatotrope, for representing Listing's 

 law of the positions of the eye. 



Professor Dr. L. Hermann, Zurich. 



This apparatus can be arranged for vertical, horizontal, or oblique axes of 

 rotation, by changing the ^position of the arcs which support the eye-balls. 

 The same number that is marked by the arc on the edge of the fixed con- 

 cave disc behind the eye-ball, must be crossed, on the equatorial ring of the 

 eye, by the red (vertical) meridian. When the axis of rotation is vertical 

 or horizontal, the blue (horizontal) meridian corresponds, during rotation, 

 with the thin brass plate (visual plane) ; when the axis of rotation is oblique, 

 the horizontal meridian and the visual plane will form an angle (the so- 

 called Raddrehungs-Winkel). 



3674. Tonometer, for Measuring the Tension and 

 Convexity of the Eye-ball. 



Geneva Association for Constructing Scientific Instru- 

 ments. 

 39508. 3 D 



