934 SEC. 18. BIOLOGY. 



3714. Dr. Giraud Teulon's Binocular Ophthalmoscope. 



M. Roulot, Paris. 



3706. R. Brudenell Carter's Demonstrating Ophthal- 

 moscope, showing the fundus oculi magnified to 12 inches in 

 diameter. T. Hawhsley. 



3707. Dr. Lionel Beale's Self - illuminating Demon- 

 strating Ophthalmoscope. May be used in daylight. 



T. Hawhsley. 



3696. Weber's Synamphophthalmoscope. 



Dr. Weber, Darmstadt. 



The apparatus serves for the simultaneous investigation of both eyes in the 

 inverted image, and thus permits a comparison of the details of the back- 

 ground of the eye as to size, colour, &c. In using it a double source of light 

 and a perforated reflector are required. 



3707a. Prof. Laqueur's. Instrument for measuring the 

 Ophthalmoscopic Image* Prof. Laqueur, Strasburg. 



3684. Apparatus for giving Instruction in the use of 

 the Ophthalmoscope; also 18 water-colour drawings in a box, 

 giving the typical aspects of the retina, choroides, and optic nerve 

 in health and disease, from nature. Dr. Magnus, Breslau. 



This apparatus presents, in a very instructive way, the various laws of refrac- 

 tion of the eye, by shifting the lens which is contained in it ; the apparatus 

 can be used for demonstration with the greatest facility. Besides these 

 physical problems, the apparatus has 18 water-colour drawings, painted by 

 the exhibitor from nature, and showing the principal features of the healthy 

 and diseased retina, choroides, and optic nerve, for the purpose of affording 

 the student the opportunity of investigating ophthalmoscopically the patho- 

 logical changes occurring inside the eye. 



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

 law of the positions of the eye. 



Prof. 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 Kaddrehungs-Winkel) . 



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



3689. Actinallactor, an instrument for demonstrating the 

 persistence of light impression on the eye. 



Prof. Buys-Ballot, Utrecht. 



It consists of a black circular cardboard, that can be turned by a handle 

 round an axle passing perpendicularly through its centre. Excentrically is 



